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portable medll receiver
OM-20000065 Rev 1
PORTABLE MEDLL RECEIVER
Installation and Operation Manual
NovAtel Inc.
Portable MEDLL Receiver
Installation and Operation Manual
Publication Number:
OM-20000065
Revision Level:
1
2002/06/21
Proprietary Notice
The software described in this document is furnished under a license agreement or non-disclosure agreement. The
software may be used or copied only in accordance with the terms of the agreement. It is against the law to copy the
software on any medium except as specifically allowed in the license or non-disclosure agreement.
No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying and recording, for any purpose without the express written permission of a duly authorized
representative of NovAtel Inc.
The information contained within this manual is believed to be true and correct at the time of publication.
GPSAntenna, GPSCard, GPSolution, MEDLLÒ, and METÒ are trademarks of NovAtel Inc.
© 2002 NovAtel Inc. All rights reserved
Unpublished rights reserved under International copyright laws.
Printed in Canada on recycled paper. Recyclable.
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Portable MEDLL Manual Rev 1
Table of Contents
TABLE OF CONTENTS
Foreword ..................................................................................................................................... viii
Scope ......................................................................................................................................................................................... viii
Prerequisites............................................................................................................................................................................... viii
Compliance with GPS Week Rollover....................................................................................................................................... viii
1
Introduction ........................................................................................................................... 1
The NovAtel Portable MEDLL Receiver...................................................................................................................................... 1
Hardware Overview ............................................................................................................................................ 2
MEDLL ........................................................................................................................................................... 3
GEO Processing .............................................................................................................................................. 3
Other Outputs & Inputs ................................................................................................................................... 3
2
Installation of Portable MEDLL Receiver............................................................................. 4
Minimum Configuration ............................................................................................................................................................... 4
User-Supplied Computer .................................................................................................................................... 5
LEDs ............................................................................................................................................................................................. 6
Connecting Data Communications Equipment ............................................................................................................................. 6
Connecting the GPS Antenna ....................................................................................................................................................... 7
Connecting the External Power Input ........................................................................................................................................... 7
Accessing the Strobe Signals ........................................................................................................................................................ 8
3
Operation ............................................................................................................................... 9
Pre-Start Check List...................................................................................................................................................................... 9
Serial Ports - Default Settings............................................................................................................................. 9
Boot-Up .............................................................................................................................................................. 9
Timing: Receiver Transmit and Receive Time ................................................................................................. 10
Initial Communications with a Portable MEDLL Receiver ........................................................................................................ 10
Valid Data and Available Logs......................................................................................................................... 11
4
Firmware Updates ............................................................................................................... 12
Obtain Files....................................................................................................................................................... 12
Decompress Files.............................................................................................................................................. 12
Run LOADER................................................................................................................................................... 12
Command-Line Mode ................................................................................................................................... 13
Updating the GPSCards in the MEDLL Receiver..................................................................................................... 13
Entire Receiver Update Mode ....................................................................................................................... 14
5
Command Descriptions ...................................................................................................... 15
$ALMA....................................................................................................................................................................................... 17
ASSIGN ...................................................................................................................................................................................... 18
$ASSIGNG2TOPRN .................................................................................................................................................................. 20
CLOCKADJUST ........................................................................................................................................................................ 21
COMn ......................................................................................................................................................................................... 22
CONFIG ..................................................................................................................................................................................... 23
CSMOOTH................................................................................................................................................................................. 24
ECUTOFF................................................................................................................................................................................... 25
FIX POSITION........................................................................................................................................................................... 26
FREQUENCY_OUT .................................................................................................................................................................. 27
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Table of Contents
LOG ............................................................................................................................................................................................ 28
RESET........................................................................................................................................................................................ 30
$SETFRAMETYPE.................................................................................................................................................................... 31
UNASSIGN ................................................................................................................................................................................ 32
UNASSIGNALL......................................................................................................................................................................... 32
$UNASSIGNG2TOPRN ............................................................................................................................................................ 32
UNDULATION .......................................................................................................................................................................... 33
UNFIX ........................................................................................................................................................................................ 34
UNLOG ...................................................................................................................................................................................... 34
UNLOGALL............................................................................................................................................................................... 34
VERSION................................................................................................................................................................................... 35
6
Output Logging ....................................................................................................................36
7
NovAtel Format Data Logs ..................................................................................................37
ASCII Log Structure................................................................................................................................................................... 37
Binary Log Structure .................................................................................................................................................................. 37
Compressed Binary Log Structure ....................................................................................................................38
Time Conventions....................................................................................................................................................................... 38
Log Descriptions......................................................................................................................................................................... 38
$AGCA/B AGC and A/D Information ..........................................................................................................39
ALMA/B Decoded Almanac.........................................................................................................................41
CDSA/B Communication and Differential Decode Status ...........................................................................43
CLKA/B Receiver Clock Offset Data ...........................................................................................................45
CRLA/B Correlator Location IN C/A chips..................................................................................................47
DOPA/B Dilution of Precision......................................................................................................................49
ETSA/B Extended Channel Tracking Status................................................................................................51
FRMA/B Framed Raw Navigation Data .......................................................................................................55
IONA/B Decoded Almanac - Ionospheric Model Parameters......................................................................56
MPMA/B Multipath Meter............................................................................................................................58
POSA/B Computed Position .........................................................................................................................60
RBTA/B Satellite Broadcast Data: Raw Bits ................................................................................................64
RCCA Receiver Configuration......................................................................................................................65
REPA/B Raw Ephemeris...............................................................................................................................66
RGEA/B/D Channel Range Measurements ...................................................................................................67
RVSA/B Receiver Status...............................................................................................................................74
SATA/B Satellite Specific Data ...................................................................................................................76
SBTA/B Satellite Broadcast Data: Raw Symbols ........................................................................................78
TM1A/B Time of 1PPS................................................................................................................................79
UTCA/B Decoded Almanac - UTC Time Parameters...................................................................................80
WBCA/B Wide Band Carrier Range Correction...........................................................................................81
WRCA/B Wide Band Code Range Correction..............................................................................................81
A
Portable MEDLL Receiver - Technical Specifications .......................................................83
B
GPS Overview ......................................................................................................................86
GPS System Design .................................................................................................................................................................... 86
The Space Segment...........................................................................................................................................87
The Control Segment ........................................................................................................................................87
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Portable MEDLL Manual Rev 1
Table of Contents
The User Segment............................................................................................................................................. 87
C
Information Messages ........................................................................................................ 88
D
Acronyms............................................................................................................................. 92
INDEX............................................................................................................................................ 94
TABLES
1
Portable MEDLL Command Summary............................................................................................................. 16
2
Portable MEDLL Logs Summary ..................................................................................................................... 36
3
GPSCard Solution Status .................................................................................................................................. 53
4
Channel Tracking Status Bits............................................................................................................................ 53
5
Bits 0 - 3 : Channel Tracking State ................................................................................................................... 54
6
Bits 12-14 : Correlator Spacing ........................................................................................................................ 54
7
Range Reject Codes .......................................................................................................................................... 54
8
MEDLL Status Bits Table ................................................................................................................................ 59
9
Reference Ellipsoid Constants .......................................................................................................................... 61
10
Transformation Parameters (Local Geodetic to WGS-84)................................................................................ 62
11
Receiver Self-Test Status Codes ....................................................................................................................... 69
12
Receiver Self-Test Status Bits........................................................................................................................... 70
13
Additional Information About Portable MEDLL Receiver Self-Test Status Word .......................................... 72
14
Range Record Format (RGED Only) ................................................................................................................ 73
15
Type 1 !ERRA Messages.................................................................................................................................. 88
16
Type 1 !MSGA Messages ................................................................................................................................. 89
17
Type 2 Information Messages........................................................................................................................... 90
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Table of Contents
FIGURES
1
The NovAtel Portable MEDLL Receiver............................................................................................................1
2
Portable MEDLL Receiver Functional Block Diagram ......................................................................................2
3
Portable MEDLL Minimum System Configuration ............................................................................................4
4
Rear Panel of Portable MEDLL Receiver...........................................................................................................5
5
Lights on Front Panel of Portable MEDLL Receiver..........................................................................................6
6
Pinout for COM Ports - Portable MEDLL..........................................................................................................6
7
Antenna Input - Portable MEDLL ......................................................................................................................7
8
External Power Connections - Portable MEDLL................................................................................................7
9
Power Switch - Portable MEDLL .......................................................................................................................7
10
Strobe 9-pin D-Connector Pinout - Portable MEDLL ........................................................................................8
11
Timing Relationships ........................................................................................................................................10
12
Height Relationships .........................................................................................................................................33
13
View of GPS Satellite Orbit Arrangement ........................................................................................................86
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Portable MEDLL Manual Rev 1
Notice
NOTICE
In accordance with the EMC Directive 89/336/EEC of the European Community including amendments by the
CE marking Directive 93/68/EEC.
The Portable MEDLL receiver, in view of its design and type of construction, fully complies with the relevant basic
radio interference requirements of the EMC Directive and qualifies to carry the CE Marking.
Should this instrument be modified without agreement, this declaration becomes invalid.
Relevant EMC Directive:
EMC Directive (89/336/EEC)
Amendment (93/68/EEC)
Applied Harmonized Standard:
EN5022 CLASS A
CISPR 11/22 CLASS A
EN50082-2: 1994 R-02
EN 61000-4-2:
1995
EN 61000-4-3:
1997
EN 61000-4-4:
1995
EN 61000-4-6:
1996
IMPORTANT: In order to maintain compliance with the limits of EMC Directive 89/336/EEC, it is required to use
properly shielded interface cables when using the Serial Ports, such as Belden #9539, or equivalent,
double-shielded cables when using the Strobe Port, such as Belden #9945, or equivalent, and Belden
#8770 cable for input power source (ensuring the shield is connected to the protection ground).
Portable MEDLL Manual Rev 1
vii
Foreword
FOREWORD
SCOPE
The Portable MEDLL Receiver Installation and Operation Manual is written for users of the Portable MEDLL receiver.
This manual describes NovAtel’s Portable MEDLL receiver in sufficient detail to allow effective integration and
operation. The manual is organized into sections, which allow easy access to appropriate information. Acronyms used in
this manual may be found in Appendix D, on Page 92.
PREREQUISITES
The Portable MEDLL receiver is a stand-alone fully functional GPS receiver. Refer to Chapter 2, Installation of
Portable MEDLL Receiver, on Page 4, for more information on installation requirements and considerations. Refer to
Appendix B, on Page 86, for an overview of GPS.
The NovAtel Portable MEDLL receiver utilizes a comprehensive user interface command structure, which requires
communications through its serial (COM) ports. To utilize the built-in command structure to its fullest potential, it is
recommended that some time be taken to review and become familiar with Chapters 6-8 of this manual before operating
the Portable MEDLL receiver.
Please also see the User-Supplied Computer section on Page5.
COMPLIANCE WITH GPS WEEK ROLLOVER
The GPS week rollover issue refers to the way GPS receivers store information regarding the current GPS week.
According to the official GPS system specifications document (ICD-GPS-200, paragraph 20.3.3.3.1.1), “… 10 bits shall
represent the number of the current GPS week…” This means an integer number between 0 and 1023 represents the GPS
week. As GPS time started on Sunday January 6, 1980 at 0:00 hours Greenwich Mean Time (GMT), week 1023 ended on
Saturday August 21, 1999 at 23:59:59 GMT.
According to the ICD-GPS specifications, the receiver should reset the GPS week number. This means that the week
number should not advance to 1024, but start back at 0. However, another way to handle this issue is to extend the
number of bits used to represent the GPS week number. This way, the GPS week would be able to increment per usual
and would not have to be reset.
Per the GPS system specifications document, NovAtel firmware resets the receiver’s GPS week number back to zero.
Different manufacturers no doubt handled this situation differently. Therefore, users should be aware of this issue and
keep in mind that there may be a compatibility issue when purchasing and using different makes of GPS receivers.
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Portable MEDLL Manual Rev 1
1 - Introduction
1
INTRODUCTION
The Portable MEDLL receiver is designed to receive, decode and output GPS signals for analysis by NovAtel’s
Multipath Assessment Tool (MAT). The primary functions of Portable MEDLL include:
·
·
·
·
·
·
data collection (for example, multipath characterization data)
determining satellite orbits
determining satellite clock corrections
determining satellite integrity
independent data verification
system operations & maintenance
THE NOVATEL PORTABLE MEDLL RECEIVER
The principal function of the Portable MEDLL receiver is to provide GPS outputs that characterize multipath
environments experienced at the receiver antenna. This is particularly important for permanent installations where signal
reflections are likely to result in significant multipath effects. The Portable MEDLL receiver together with MAT can be
used to analyse and select permanent reference station sites.
Figure 1
The NovAtel Portable MEDLL Receiver
The NovAtel Portable MEDLL receiver is a high-performance GPS & GEO receiver that provides accurate multipath
characterization data. NovAtel has developed a multipath elimination technology that approaches the theoretical limits of
multipath-free GPS signal reception. This patented technology, known as “Multipath Estimating Delay-Lock-Loop”
(MEDLL), uses a combination of hardware and software techniques which together are capable of reducing the combined
effects of pseudorange and carrier-phase multipath errors by as much as 90% compared to a system using a standard
correlator alone. The MEDLL technology takes advantage of NovAtel’s parallel channel correlator sampling techniques.
MEDLL uses a proprietary coupled correlator sampling technique combined with “maximum likelihood estimation”
techniques to break down the received signals into direct path and reflected path components. MEDLL determines the
amplitude, delay, and phase angle of both the direct and multipath signals and analyses the signal with the least delay to
determine the direct path. The Portable MEDLL firmware provides multipath amplitude, delay and phase data for
subsequent analysis. To do this, MEDLL utilizes a multi-card configuration. Each L1 GPSCard in the MEDLL receiver is
Portable MEDLL Manual Rev 1
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1 - Introduction
linked to one common radio frequency (RF) deck and an oven controlled crystal oscillator (OCXO) that minimizes interchannel biases.
The Portable MEDLL receiver is packaged in a portable instrumentation case. The rear panel’s connectors provide easy
access to strobes, communication, power and an antenna.
HARDWARE OVERVIEW
The NovAtel Portable MEDLL receiver consists of a Master card and five Slave cards, see Figure 2.
Figure 2
Portable MEDLL Receiver Functional Block Diagram
From Antenna
Portable
MEDLL
Back Plane
Digitized
Signal
MEDLL
Master
Card
Digitized Signal
MEDLL
Slave
Cards
COM1 1 PPS COM2
MEDLL Cards
The receiver provides:
a)
L1 GPS and GEO data
b) a 1PPS output
c)
2
COM ports for bi-directional communication with a computer
Portable MEDLL Manual Rev 1
1 - Introduction
MEDLL
MEDLL is implemented across a number of standard NovAtel 12 channel GPS receivers. Through parallel linking of
these separate receiver modules, MEDLL may be configured to behave as a single GPS receiver, capable of
simultaneously tracking 10 GPS satellites and 2 GEO satellites, or 12 GPS satellites and no GEO satellites.
A single incoming RF signal is routed to a Master Card (Master), which down converts the signal to baseband frequency
for parallel processing by five Slave Receivers (Slaves). The baseband signal is then processed by twelve parallel digital
signal-processing sections, through Multiple Independent Nomadic Stargazer (MINOS) Application Specific Integrated
Circuits (ASICs), and NovAtel patented MEDLL tracking technology.
Across the twelve processing sections, there are a total of 72 tracking channels. Six channels are dedicated to tracking
each GPS or GEO satellite, and these channels are positioned around the associated correlation envelope. By a process of
continuous comparison of the signals measured by each channel, any distortion from the ideal correlation envelope can be
detected, tracked, qualified and removed. This process allows the receiver to isolate and eliminate multipath distortions
from the received signal.
The Master and Slave receivers are mounted in a portable instrumentation case, and are supplied power from an
integrated power conditioner. Stable clock signals are derived from a precision internal oscillator. Status indicators on the
front panel provide visual confirmation of the health of each electronic sub-assembly within the case.
Signals are routed to and from the MEDLL receiver via an RF antenna input, power and digital I/O signal connector on
the rear of the unit.
The unit is controlled via RS-232 using standard NovAtel commands, and data is output in NovAtel output logs. Specific
MEDLL logs provide access to the MEDLL processing data.
GEO Processing
Specific channels in the MEDLL receiver have the capability to receive and process the GEO signals. The signal is inband at L1 and is identified with GEO-specific PRN numbers. The GEO message is decoded and separated into its
various components. The GEO message and associated pseudorange is provided as an output.
Other Outputs & Inputs
·
A 1 pulse per second (1PPS) strobe output from the MEDLL master. Timing information of this pulse is available
in the TM1A log, see Page 79.
·
The COM1 and COM2 ports provide: - raw satellite measurements (pseudorange, carrier & time)
- receiver status data (communications & tracking)
- raw satellite data (ephemeris & almanac)
- fast code corrections for signal stability monitoring
- logs for the MAT software
Portable MEDLL Manual Rev 1
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2 - Installation of Portable MEDLL Receiver
2
INSTALLATION OF PORTABLE MEDLL RECEIVER
This chapter provides sufficient information to allow you to set up and prepare the Portable MEDLL receiver for standalone operation.
MINIMUM CONFIGURATION
In order for the Portable MEDLL receiver to function as a complete system, a minimum equipment configuration is
required. This is illustrated in Figure 3.
Figure 3
Portable MEDLL Minimum System Configuration
GPS L1 Antenna
A/C Input Power
(24 VDC @ 3A)
Portable MEDLL Receiver
User-supplied Computer
The recommended minimum configuration and required accessories are listed below:
·
·
·
·
·
·
NovAtel Portable MEDLL receiver
L1 GPSAntenna and low noise amplifier (LNA)
Power supply (22-30 VDC, 3 A maximum)
User-supplied computer, please see the same named section on the next page
RF cables
User-supplied data cable
Of course, your intended set-up may differ significantly from this configuration. This section describes the basic system
configuration, which you can modify to meet your specific situation.
For the configuration in Figure 3, setting up the Portable MEDLL receiver involves the following steps:
1.
Connect your computer to the Portable MEDLL receiver (“COM1” or “COM2”connector)
Your computer must be fast enough to accept all logs requested at the configured data rates. It is recommended
that the serial port be configured to the fastest compatible rate supported by both the receiver and the computer.
If data collection is planned over an expanded period, 24 hours for example, ensure the data storage capacity is
adequate for the logs requested. (NovAtel recommends Microsoft Windows 2000 or later as the computer
operating system). If logs are missing in the data record, then the requested logs and logging rates exceed the
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Portable MEDLL Manual Rev 1
2 - Installation of Portable MEDLL Receiver
receiver/computer communications capability. In this case, it is suggested that you reduce the logging rate or
increase the serial communication rate.
2.
Install the GPS antenna and low noise amplifier, and make the appropriate connections to the Portable MEDLL
receiver (“ANT” connector)
3.
Supply power in the range 22 to 30 VDC to the Portable MEDLL receiver (“+24 VDC” connector)
The connections on the rear panel are shown in Figure 4.
Figure 4
Rear Panel of Portable MEDLL Receiver
USER-SUPPLIED COMPUTER
Recommended user supplied computer prerequisites:
a. A laptop computer or workstation with Windows 2000 Professional, SR-1 or later.
b. Hard disk with at least 400MB for free space for each 24 hours of data. Please note that this storage requirement is
after subtracting any “Virtual RAM” allocated to the operating system.
c. RAM, 128MB
d. CPU, 300 MHz Pentium 3 or equivalent. Note that the CPU speed requirement depends on other processing
requirements. This recommendation assumes the computer is used for data collection only.
e. Archival data storage. It is recommended that any data collected with the receiver be placed on archive media such as
a CD-ROM as a contingency against a disk drive failure.
f. A high quality null modem cable for connection between the receiver and the user supplied computer. NovAtel
recommends NovAtel part number 60715062 or equivalent.
Portable MEDLL Manual Rev 1
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2 - Installation of Portable MEDLL Receiver
LEDS
The LEDs on the front panel indicates the status of the Portable MEDLL receiver’s 6 cards. They should turn from red to
green to let you know the Portable MEDLL receiver’s serial ports are healthy and ready to communicate, see Figure 5
following.
Figure 5
Lights on Front Panel of Portable MEDLL Receiver
CONNECTING DATA COMMUNICATIONS EQUIPMENT
There are two serial ports on the back panel of the Portable MEDLL receiver; both are configured for RS-232 protocol.
These ports make it possible for external data communications equipment - such as a personal computer - to
communicate with the Portable MEDLL receiver. Each of these ports has a DE9P connector.
·
The COM1 and COM2 ports (see Figure 6) allow two-way communication. They are connected to the MEDLL
master card.
Figure 6
6
Pinout for COM Ports - Portable MEDLL
Portable MEDLL Manual Rev 1
2 - Installation of Portable MEDLL Receiver
CONNECTING THE GPS ANTENNA
Selecting and installing an appropriate antenna system is crucial for proper operation of the Portable MEDLL receiver.
Keep the following points in mind when installing the antenna system:
·
Ideally, select an antenna location with a clear view of the sky to the horizon so that each satellite above the horizon
can be tracked without obstruction.
·
Ensure that the antenna is mounted on a secure, stable structure capable of withstanding relevant environmental
loading forces (e.g. due to wind or ice).
Use high-quality coaxial cables (NovAtel 5m cable, part number C005, for example) to minimize signal attenuation. The
gain of the LNA must be sufficient to compensate for the cabling loss. The MEDLL receiver supplies 5 A to power the
LNA.
The antenna port on the Portable MEDLL receiver has a TNC female connector, as shown in Figure 7.
Figure 7
Antenna Input - Portable MEDLL
CONNECTING THE EXTERNAL POWER INPUT
The Portable MEDLL receiver provides one external regulated power supply. The input can be in the 22-30 VDC range.
The receiver draws up to 3 A at start-up, but the steady-state requirement is approximately 1.5 A.
The power-input connector on the Portable MEDLL receiver connects to the Portable MEDLL receiver’s internal power
supply, which performs filtering and voltage regulation functions. Refer to Figure 8, which shows the external power
connection on the Portable MEDLL receiver.
Figure 8
External Power Connections - Portable MEDLL
Centre pin is positive
To ensure proper operation, the power switch, see Figure 9, must be used for applying power to the receiver. First, an
external power supply must be connected to the receiver with the power switch in the OFF position (down).
Figure 9
Power Switch - Portable MEDLL
ON
OFF
Portable MEDLL Manual Rev 1
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2 - Installation of Portable MEDLL Receiver
ACCESSING THE STROBE SIGNALS
The Portable MEDLL receiver’s output strobe lines are available on the rear panel from the DE9S connector (see Figure
10). The specifications and electrical characteristics of these signals are described in Appendix A, starting on Page 83.
These signals are provided for diagnostic purposes.
The COM ports are connected to the MEDLL master card.
Figure 10
Strobe 9-pin D-Connector Pinout - Portable MEDLL
STATUS
Reserved
MSR
1 PPS
VARF
GND
GND
GND
GND
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Portable MEDLL Manual Rev 1
3 - Operation
3
OPERATION
Before operating the Portable MEDLL receiver for the first time, ensure that you have followed the installation
instructions in Chapter 2.
From here on, it will be assumed that testing and operation of the Portable MEDLL receiver will be performed while
using a personal computer (PC); this will allow the greatest ease and versatility.
PRE-START CHECK LIST
Before turning on power to the Portable MEDLL receiver, ensure that all of the following conditions have been met:
·
The antenna is properly installed and connected.
·
The PC is properly connected using a null-modem cable, and its communications protocol has been set up
to match that of the Portable MEDLL receiver (see the Serial Ports section below).
Supply power to the Portable MEDLL receiver only after all of the above checks have been made. Note that the warm-up
process may take several minutes, depending on ambient temperature. Required start-up time (cold start) is 5 minutes.
This is for the OCXO to stabilize.
It is recommended that you do a complete receiver reset by sending a RESET command after 5 minutes, following a cold
start. This allows a recalibration of the receiver algorithm after RF components have warmed up. It also allows the
automatic sky search routine to reset.
If this power-up order is not followed, the start-up times will not be achieved. The limiting factor in achieving the start-up
times is the OCXO becoming stable.
SERIAL PORTS - DEFAULT SETTINGS
Because the Portable MEDLL receiver communicates with the user’s PC or core computer via serial ports, both units
require the same port settings. The communications settings of the PC should match these on the receiver:
·
·
·
·
·
·
·
RS-232 protocol
9600 bits per second (bps)
No parity
8 data bits
1 stop bit
No handshaking
Echo off
Once initial communications are established, the port settings for the Portable MEDLL receiver can be changed using the
COMn command, which is described on Page 22.
BOOT-UP
The Portable MEDLL receiver’s firmware resides in non-volatile memory. Supply power to the unit, wait a few moments
for self-boot, and the Portable MEDLL receiver will be ready for command input.
On receiver start-up, the integrity of the random-access memory (RAM) is checked. If the RAM check fails, the receiver
waits for operator intervention. If the RAM check completes successfully, the authorization code is verified in order to
check the integrity of the software load. If this check fails, an associated message will be output from the receiver (see
Appendix C Information Messages starting on Page 90). Following the authorization code check, the configuration of
the receiver is verified. The default configuration for the receiver model will be applied (see Appendix A
Portable
Portable MEDLL Manual Rev 1
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3 - Operation
MEDLL Receiver - Technical Specifications starting on Page 83). After these checks have been completed, the receiver
will output the COM port prompt indicating everything has started correctly and the receiver will accept commands.
A read-back check of the ASIC and a loop-back test of the COM ports are also included in the start-up test sequence to
make sure that they are functioning properly. In the event of a failure of either of these checks, the associated bit will be
set in the receiver status word (see Table 12 on Page 70). If it has been determined that the COM port has failed, the
COM prompt may not be output, depending on the nature of the failure.
There are two initial start-up indicators to let you know that the Portable MEDLL receiver’s serial ports are ready to
communicate:
1.
Status lights on the Portable MEDLL receiver’s front panel should turn from red to green to indicate that all cards
are healthy. If any one of the LEDs does not turn green, then the system should be considered unreliable. If this
situation occurs, the receiver requires maintenance.
2.
Your external computer screen will display one of the following prompts:
Com1> (if you are connected to the COM1 port.)
Com2> (if you are connected to the COM2 port.)
The Portable MEDLL receiver is now ready for command input from the COM1 or COM2 port.
TIMING: RECEIVER TRANSMIT AND RECEIVE TIME
Transmit time is defined as the time when the last bit of the GPS signal leaves the satellite antenna. Receive time is when
the last bit is removed from the MINOS chip. For example, the SFD log has receive time and transmit time. The transmit
time is when the last bit that belongs to a 1 second accumulation leaves the satellite antenna. Receive time is the time that
the last bits of the 1 second accumulation are taken from the MINOS register. Figure 11 shows the timing relationships
within the Portable MEDLL receiver.
Figure 11
Timing Relationships
1 second UTC
GEO Message at Satellite
GEO Message at Receiver Input
GEO Message at Receiver Output
GEO Message Receive Time
GEO Message Transmit Time
GPS Message at Satellite
GPS Message at Receiver Input
GPS Message at Receiver Output
GPS Message Receive Time
GPS Message Transmit Time
Receiver Snapshot of Tracking
Satellite Range Data Sent from Receiver
INITIAL COMMUNICATIONS WITH A PORTABLE MEDLL RECEIVER
Communicating with the Portable MEDLL receiver is accomplished by issuing commands to a COM port from an
external serial communications device.
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Portable MEDLL Manual Rev 1
3 - Operation
The software on the PC could be one of the following:
1. Terminal Emulator (e.g. HyperTerminal)
2. GPSolution
3. Multipath Assessment Tool (MAT) is recommended
To change the default communication settings, such as bit rate, use the COMn command, see Page 22.
It is to your advantage to become thoroughly familiar with Chapters 5 through 7 of this manual to ensure maximum
utilization of the Portable MEDLL receiver’s capabilities.
When the Portable MEDLL receiver is first powered up, no activity information is transmitted from the COM ports
except for the COM1> or COM2> prompt described in the Boot-up section on Page 9. Receipt of the prompt confirms
the boot process is complete and the receiver is ready to accept commands.
Commands are directly input to the Portable MEDLL receiver using the external computer. It should be noted that most
commands do not echo a response to a command input. Your indicator that the command has actually been accepted is a
return of the COM1> or COM2> prompt from the Portable MEDLL receiver. Note that VERSION is the only command
that does provide an echo response instead of the port prompt.
Examples:
1.
If you type VERSION <Enter> from a terminal, this will cause the Portable MEDLL receiver to echo the firmware
version information.
2.
An example of a no-echo response to an input command is the FIX POSITION command. It can be input as follows:
COM1>fix position 51.113 -114.043 1060 <Enter>
This example illustrates command input to the COM1 port, which sets the Portable MEDLL receiver’s position.
However, your only confirmation that the command was actually accepted is the return of the COM1> prompt.
If a command is erroneously input, the Portable MEDLL receiver will respond with either the “Invalid Command
Option” or “Invalid Command Name” response followed by the COMn> prompt.
VALID DATA AND AVAILABLE LOGS
15 minutes after a cold start, all logs are available and the data within the logs is valid.
You can also monitor the log output for indication that the receiver output is valid. (i.e. FINETIME is set, position is
valid, almanac is valid)
Portable MEDLL Manual Rev 1
11
4 - Firmware Updates
4
FIRMWARE UPDATES
The method of updating the firmware in the Portable MEDLL receiver is with a manual update process described
following.
GPSCards store their firmware (program software) in on-board, non-volatile memory. This unique feature allows a
receiver’s firmware to be updated in the field. Thus, a procedure such as updating software model EGNOSMEDLL rev.
5.4441S7 to EGNOSMEDLL rev. 5.45 takes only a few minutes instead of the several days which would be required if
the receiver had to be sent to a service depot.
The MEDLL system is updated by means of a serial connection to the host PC using a COM port.
When updating the receiver, you will need to transfer the new firmware to the appropriate GPSCard with the aid of the
NovAtel-supplied utility program, “LOADER”. To update firmware while using LOADER, you will need a personal
computer with the following features:
·
·
·
·
MS-DOS 6.0 or later
one available RS-232 serial port
null-modem cable
at least 1 MB of available hard drive space
Below is an outline of the procedure for updating your receiver’s firmware:
1.
2.
3.
Obtain firmware update files from NovAtel
Decompress files
Run LOADER in one of three modes: Menu, Command Line, or Entire Receiver Update.
OBTAIN FILES
The files are available in compressed, password-protected file format. The compressed form of the files will have
differing names; NovAtel will advise you as to the exact names of the files you need. As well, NovAtel will provide you
with a file decompression password.
DECOMPRESS FILES
After copying the compressed files to an appropriate directory on your PC, each file must be decompressed. The syntax
for decompression is as follows:
Syntax:
[filename] -s[password]
Where:
filename:
-s:
password:
is the name of the compressed file (excluding the extension)
is the password command switch
is the password required to allow decompression
Example:
m54441S7 -s12345678<Enter>
RUN LOADER
LOADER should be copied to the hard drive of your personal computer and run from the command (DOS) prompt. Once
LOADER is installed and running, it allows you to select and configure a PC serial port, as well as choose the directory
12
Portable MEDLL Manual Rev 1
4 - Firmware Updates
path and file name of the new program software to be transferred to the GPSCard. After the LOADER parameters have
been selected and the auth-code entered, the actual file transfer only takes a few minutes, depending on the data transfer
rate selected. LOADER also contains built-in terminal software.
LOADER will instruct you when to turn on and off the Portable MEDLL receiver.
Run LOADER in one of these modes:
1.
Command-Line mode:
This allows you to set up a batch process to update the multiple
cards within the MEDLL.
2.
Entire Receiver Update mode:
Use this if you wish to update all of the GPSCards in the MEDLL
system within the Portable MEDLL in a single operation.
Command-Line Mode
LOADER may be used with command line options directly at the DOS command prompt. In this mode of operation the
filename and authorization code can be specified on the command line. When the program detects a filename and
authorization code, it immediately proceeds to read the specified file, authorize it and send it to the Portable MEDLL
receiver. The syntax is in the section that follows.
Updating the GPSCards in the MEDLL Receiver
A batch file can be used to provide a convenient way to program multiple GPSCards with the same or different versions
of software. Rather than having to run LOADER once for each card, you can specify the card number, firmware filename
and an optional authorization code in a batch file.
The batch file is a simple ASCII text file and should be formatted as shown in the example below. In this example, Card
#1 is to be loaded with software in the M544.BIN file, and remaining cards with the S544.BIN file. Cards #2-#8 have no
authorization codes. The batch file should be in the same directory as the LOADER program.
Syntax #2:
LOADER
-b<batchfile>
-h
-b<batchfile>
Specifies file with multiple load commands.
Requests on-line help.
Examples:
loader –h
loader -bmedll.txt
In the second example, this would be the listing of the MEDLL.TXT file for a MEDLL receiver consisting of one master
card and five slave cards:
1 m54441S7.bin 1234,5678,9012,3456,EGNOSMEDLL
2 s54441S7.bin
3 s54441S7.bin
4 s54441S7.bin
5 s54441S7.bin
6 s54441S7.bin
The LOADER program will only initialise the number of cards required to complete the programming. Once the cards
have been initialised, the screen will show this:
Programming card: 1 with M54441S7.BIN
As the card is being programmed, a character to the right of the filename will spin indicating programming activity.
When the first card has been programmed, the screen will show this:
Portable MEDLL Manual Rev 1
13
4 - Firmware Updates
Programming card: 1 with M54441S7.BIN
Erasing card: 2
\
Okay
This process will continue until all of the requested cards are programmed and the screen will look similar to this:
Programming card: 1 with
Programming card: 2 with
.
.
Programming card: 6 with
Done. Resetting Cards
Initialisation took:
Programming took:
Total Time:
Press ENTER to exit
M54441S7.BIN
S54441S7.BIN
Okay
Okay
S54441S7.BIN
Okay
27 seconds
114 seconds
141 seconds
Once all of the cards have been programmed, they will be reset. Using PC communication software, or the terminal
emulator in the Menu mode of LOADER, issue the VERSION command to verify your new program version number.
Warning! Master and slave sections need the same software version or the receiver will fail at start-up.
Entire Receiver Update Mode
If you wish to perform an update of all the GPSCards in a Portable MEDLL receiver, this mode of LOADER will guide
you through the process and simplify the operation considerably. Together with the LOADER program and the update
files that you received from NovAtel, there will also be a file with a name such as UPDATE.BAT. This is a batch file
which runs LOADER in Command Line mode as described above, with all the commands already prepared.
To run the software, you will need to issue the following command: Syntax #3:
UPDATE
<serial port>
<data transfer rate>
<serial port>
<data transfer rate>
Specifies which serial port (COM port) on your computer is to be used
Specifies the data transfer rate that is to be used
Examples:
update 2 115200
This example instructs the UPDATE utility to upgrade the GPSCard, which is connected to the PC's serial port 2
(COM2) at 115,200 bits per second. The utility will prompt you to turn the power to the Portable MEDLL receiver on or
off; it will also prompt you to connect your personal computer to a COM port on the Portable MEDLL receiver.
By the time this utility completes its task, you will have connected your computer to a COM port on the Portable MEDLL
receiver and updated all the GPSCards inside.
14
Portable MEDLL Manual Rev 1
5 – Command Descriptions
5
COMMAND DESCRIPTIONS
This chapter describes the commands accepted by the Portable MEDLL receiver. They are listed in alphabetical order.
The Portable MEDLL receiver is capable of responding to many different input commands. You will find that once you
become familiar with these commands, the Portable MEDLL receiver offers a wide range in operational flexibility.
Commands can be sent to the Portable MEDLL receiver through the COM1 or COM2 serial port.
You can issue these commands to control the following:
1.
2.
3.
Overall status of the Portable MEDLL receiver
Input & output functions
Configuration of a specific channel of the Portable MEDLL receiver
Table 1 shows the list of commands arranged alphabetically.
When the Portable MEDLL receiver is first powered up, all commands revert to the factory default settings. Each
command description in this chapter also lists its default setting.
The following rules apply when communicating with the card:
1.
·
·
The commands are not case sensitive.
e.g.
VERSION or version
e.g.
FIX POSITION or fix position
2.
·
·
·
·
·
·
All commands and required entries can be separated by a space or a comma.
e.g.
fix,position,51.3455323,-117.289534,1002
e.g.
fix position 51.3455323 -117.289534 1002
e.g.
com1,9600,n,8,1,n,off
e.g.
com1 9600 n 8 1 n off
e.g.
log,com1,frmb,onnew
e.g.
log com1 frmb onnew
3.
At the end of a command or command string, press <Enter>.
4.
Successful entry of a command is verified by receipt of the COM port prompt (i.e. COM1>). Exceptions to this
statement are the VERSION, RESET and CONFIG commands where the latter two commands restart the
computer. Commands entered in error will return either an “INVALID COMMAND OPTION” or “INVALID
COMMAND NAME” string.
Portable MEDLL Manual Rev 1
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5 – Command Descriptions
Table 1
Command
Portable MEDLL Command Summary
Description
$ALMA
Almanac decoder
ASSIGN
$ASSIGNG2TOPRN
CLOCKADJUST
COM1
CONFIG
CSMOOTH
ECUTOFF
FIX POSITION
Assign a PRN to a channel #
Assign a G2 delay to a PRN
Adjust 1PPS continuously
Initialize Serial Port 1
Implements pre-defined configurations
Sets code smoothing
Set elevation cutoff angle (degrees)
Set antenna coordinates for monitor station
Syntax
$alma prn,ecc,seconds,week,w,ra,w,M0,af0,af1,
corr-mean-motion,A,incl-angle,health-4,
health-5,health-alm
assign channel,prn,[doppler], [search window]
$assigng2toprn prn g2_delay
clockadjust switch
com1 baud,parity,databits,stopbits, handshake,echo,[fifo]
config [keyword]
csmooth value,[value2]
ecutoff angle
fix position lat,lon,height,[station id],[health]
FREQUENCY_OUT
LOG
RESET
$SETFRAMETYPE
UNASSIGN
UNASSIGNALL
$UNASSIGNG2TOPRN
UNDULATION
UNFIX
UNLOG
UNLOGALL
VERSION
Choose data logging type
Performs a CPU reset
Sets the type of navigation frame data output in the
FRMA/B log
Un-assign a channel
Un-assign all channels
Un-assign a G2 delay
Choose undulation
Remove all receiver FIX constraints
Cease logging a data log
Cease logging all data logs
Current software level
log [port],datatype,[trigger],[period],[offset],[hold]
reset
$setframetype type
unassign channel
unassignall
$unassigng2toprn prn
undulation separation
unfix
unlog [port],data type
unlogall
version
The syntax tables contain the start-up defaults for each command. If a command has optional parameters, the syntax table
for that command will also have a default parameters column.
16
Portable MEDLL Manual Rev 1
5 – Command Descriptions
$ALMA
Enter almanac parameters for sub-frames four and five. Enter parameters for each SV almanac required.
When the $ALMA log is input to the receiver, it should be input in exactly the same format as it was originally logged
from the receiver. Therefore, there should be no concerns about the required accuracy of the input parameters.
For more information on Almanac data, refer to the GPS SPS Signal Specification.
Syntax:
$ALMA
Syntax
$ALMA
prn
ecc
seconds
week
w
ra
w
Mo
prn ecc seconds
A incl-angle
Range Value
N/A
(The $ALMA command
is generated directly
from the ALMA log and
therefore the core
computer should never
need to change or verify
the almanac data.)
week w
health-4
ra
w
M0 af0 af1 corr-mean-motion
health-5 health-alm
Description
Command
Satellite PRN number for message
Eccentricity
Almanac reference time, seconds into the week
Almanac reference week (GPS week number)
Rate of right ascension, radians/second
Right ascension, radians
Argument of perigee, radians
Mean anomaly, radians
af0
af1
Clock aging parameter, seconds
cor-meanmotion
A
incl-angle
health-4
health-5
health-alm
Corrected mean motion, radians/second
Start-Up Default
N/A
(When Portable MEDLL receivers
start up, there is no almanac
available.)
Clock aging parameter, seconds/second
Semi-major axis, metres
Angle of inclination, radians
Anti-spoofing and SV config (sub-frame 4, page 25)
SV health, 6 bits/SV (sub-frame 4 or 5, page 25)
SV health, 8 bits (almanac)
Example:
$alma 17,1.23692E-002,503808,67,-8.0346E-009,-1.4494328E+000,3.06213275E+000,
-1.4963308E+000,-2.8706E-004,-3.6380E-012,1.45856126E-004,2.65600872E+007,
9.83002E-001,1,0,0
Portable MEDLL Manual Rev 1
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5 – Command Descriptions
ASSIGN
At start-up, the Portable MEDLL receiver automatically searches for GPS satellites (PRN 1-32). However, the PRN for
GEO satellites must be manually assigned to a receiver channel using the ASSIGN command.
This command may be used to aid in the initial acquisition of a satellite by allowing you to override the automatic
satellite/channel assignment and reacquisition processes with manual instructions. The command specifies that the
indicated tracking channel searches for a specified satellite at a specified Doppler frequency within a specified Doppler
window. The instruction will remain in effect for the specified channel and PRN, even if the assigned satellite
subsequently sets. If the satellite Doppler offset of the assigned channel exceeds that specified by the ‘search-window’
parameter of the ASSIGN command, the satellite may never be acquired or re-acquired. To cancel the effects of
ASSIGN, you must issue the UNASSIGN or UNASSIGNALL command, or reboot the Portable MEDLL receiver.
When using this command, NovAtel recommends that you monitor the channel tracking status of the assigned channel
and then use the UNASSIGN or UNASSIGNALL commands to cancel the command once the L1 channel has reached
channel tracking state 4, the Steady State Tracking state. Refer to Table 4, on Page 53, for an explanation of the various
channel states. See also the $ASSIGNG2TOPRN command on Page 20. However, this is not recommended for GEO
satellites. GEO satellites should be assigned without specifying a Doppler value or a Doppler search-window.
NOTES: Assigning a PRN to a channel does not remove the PRN from the search space of the automatic searcher; only
the channel is removed.
By default, the automatic searcher only searches for the GPS satellites (PRNs 1-32).
There are two syntactical forms of this command, as shown following.
18
Portable MEDLL Manual Rev 1
5 – Command Descriptions
Syntax #1:
ASSIGN
Syntax
ASSIGN
Channel
Prn
[Doppler]
channel
[Doppler] [Search-window]
Range Value
Description
Start-Up Default
0 - highest
channel number
1 - 999
Command
Desired channel number from 0 to maximum
channel number inclusive
A satellite PRN integer number from 1 to 32
inclusive (for GPS), 120 to 138 inclusive (for
GEO), or 1 to 999 inclusive if PRNs are
assigned using the $ASSIGNG2TOPRN
command.
Current Doppler offset of the satellite
Note: Satellite motion, receiver antenna
motion and receiver clock frequency error must
be included in the calculation for Doppler
frequency.
Error or uncertainty in the Doppler estimate
above in Hz
Note: Any positive value from 0 to 10000 will
be accepted. Example: 500 implies ± 500 Hz.
UNASSIGNALL 1
-100,000 to
100,000 Hz
Search-window
prn
0 - 10,000
Parameter Default
-100000 < Doppler < 100000
10000
Example 1:
assign 0,29,0,2000
In Example 1, the first channel will try to acquire satellite PRN 29 in a range from -2000 Hz to 2000 Hz until the satellite
signal has been detected.
Syntax #2:
ASSIGN
Syntax
ASSIGN
Channel
Keyword
channel
keyword
Range Value
Description
0 - highest channel
number
IDLE
Command
Desired channel number from 0 to maximum
channel number inclusive
Idles channel (not case sensitive)
Start-Up Default
UNASSIGNALL
1
Example 2:
assign 11,idle
In Example 2, Channel 11 will be idled and will not attempt to search for satellites.
1
This is issued automatically at start-up.
Portable MEDLL Manual Rev 1
19
5 – Command Descriptions
$ASSIGNG2TOPRN
This command allows you to link a satellite PRN with a particular G2 delay. This delay is then added to a user-defined
table, which allows up to 100 entries. Hence, when an ASSIGN command is issued, the receiver will check the userdefined table first and if the PRN is listed there, it will use that G2 delay. Otherwise it will use the default values for GPS
and GEO satellites. This command affects the C/A code tracking only.
Use the $UNASSIGNG2TOPRN command to delete a G2 delay assignment for a particular PRN from the user-defined
table.
Syntax:
$ASSIGNG2TOPRN
Syntax
Range Value
$ASSIGNG2TOPRN
Prn
G2 delay
1 – 999
0 – 1023
prn
G2 delay
Description
Command
PRN Number
C/A code G2 delay
Start-Up Default
(see footnote) 2
(see footnote) 2
Example:
$assigng2toprn 32 862
2
20
Defaults are as defined in the GPS Interface Control Document (ICD) and the WAAS Minimum Operational
Performance Standards (MOPS).
Portable MEDLL Manual Rev 1
5 – Command Descriptions
CLOCKADJUST
All oscillators have some inherent drift characterization. This command, if enabled, permits software to model these
long-term drift characteristics of the clock. The correction is applied to the 1PPS strobe as well. The clock adjustment is
performed digitally. As a result, the 1PPS Strobe (on an L1 card) will have a 49 ns jitter on it due to the receiver's
attempts to keep it as close as possible to GPS time.
CLOCKADJUST must be disabled if you wish to measure the drift rate of the oscillator using the CLKA/B data log.
NOTES: 1. Do not disable this command after 30 seconds from power-up: unpredictable clock drifts may result.
2. When disabled, the range measurement bias errors will continue to accumulate with clock drift and the
1PPS output from the receiver will drift with the internal clock.
3. This feature should only be changed by advanced users.
Syntax:
CLOCKADJUST
Syntax
switch
Range Value
CLOCKADJUST
switch
Enable or disable
Description
Command
Allows or disallows adjustment to the internal clock
Start-Up Default
ENABLE
Example:
clockadjust disable
Portable MEDLL Manual Rev 1
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5 – Command Descriptions
COMn
This command permits you to configure the COM port’s asynchronous drivers.
The COM1 and COM2 ports allow two-way communications. Thus you may enter COM1 or COM2 as the command
name.
Syntax:
COM1
Syntax
COMn
bps
parity
databits
stopbits
handshake
echo
FIFO
bps parity databits
Range Value
n = 1 or 2
300, 600, 1200,
2400, 4800,
9600, 19200,
38400, 57600 or
115200
N (none), O (odd)
or E (even)
7 or 8
1 or 2
N (none), XON
(Xon/Xoff) or
CTS (CTS/RTS)
ON or OFF
ON or OFF
stopbits
Description
COM1 or COM2
Specify bit rate
handshake echo
Start-Up Default
Parameter Default
com1
9600
Specify parity
N
Specify number of data bits
Specify number of stop bits
Specify handshaking
8
1
N
Specify echo
Enable or disable the 16550 UART’s
transmit FIFO
[FIFO]
OFF
ON
(see footnote) 3
Examples:
com1 19200,e,7,1,n,on, off
com2 1200,e,8,1,n,on, off
3
22
The default is set to whatever value was last used.
Portable MEDLL Manual Rev 1
5 – Command Descriptions
CONFIG
This command switches the channel configuration of the COMn code receiver between pre-defined configurations. When
the command is issued the receiver resets with the new configuration.
Syntax:
CONFIG
Syntax
CONFIG
keyword
Range Value
G10W2
G12W0
[keyword]
Description
Command
Configures the COMn code portion of the
MEDLL receiver to track up to 10 GPS
satellites & 2 GEO satellites.
Configures the COMn code portion of the
MEDLL receiver to track up to 12 GPS
satellites.
Start-Up Default
G10W2
Parameter Default
(see footnote) 4
Example:
config g10w2
4
The default is set to whatever value was last used.
Portable MEDLL Manual Rev 1
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5 – Command Descriptions
CSMOOTH
This is the code smoothing command for the DLL filter bandwidth. The ‘value’ field sets the L1 channel. This value is
the reciprocal of the noise equivalent bandwidth of the DLL filter. Upon issuing the command, the locktime for all
tracking satellites is reset to zero, and each pseudorange smoothing filter is restarted. You must wait for at least the length
of the smoothing time for the new smoothing constant to take full effect. 20 seconds is the default smoothing constant
used in the Portable MEDLL receiver.
NOTES: The CSMOOTH command should only be used by advanced users. It may not be suitable for every GPS
application. When using CSMOOTH in a differential mode, the same setting should be used at both the
monitor and remote station.
The lower the smoothing constant, the noisier the measurement will be.
Syntax:
CSMOOTH
Syntax
CSMOOTH
Value
value
Range Value
Description
Start-Up Default
10 to 1000
Command
L1 code smoothing constant (in seconds).
20
Parameter Default
Example:
csmooth 20
24
Portable MEDLL Manual Rev 1
5 – Command Descriptions
ECUTOFF
This command sets the elevation cut-off angle for usable satellites. The receiver will not start tracking a satellite until it
rises above the cut-off angle. If a satellite being tracked drops below this angle, it will no longer be tracked.
This command permits a negative cut-off angle, which could be used in these situations:
·
·
the receiver is at a high altitude, and thus can look below the local horizon
satellites are visible below the horizon due to atmospheric refraction
NOTES: 1. When ECUTOFF is set to zero (0), the receiver will track all satellites in view including some within a few
degrees below the horizon.
2. Care should be taken when using ECUTOFF because the signals received from low-elevation satellites
travel along a longer atmospheric path and thus tend to experience greater degradation.
3. If a satellite has been assigned to a specific channel (via the ASSIGN command), the receiver will
continually attempt to track the satellite regardless of the elevation.
Syntax:
ECUTOFF
Syntax
ECUTOFF
Angle
angle
Range Value
-90° to +90°
Description
Command
Angle value in degrees (relative to the horizon).
Start-Up Default
+5
Example:
ecutoff 5
Portable MEDLL Manual Rev 1
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5 – Command Descriptions
FIX POSITION
Invoking this command will result in the Portable MEDLL receiver position being held fixed. A computation will be
done to solve local clock offset, pseudorange, and pseudorange differential corrections. This mode of operation can be
used for time transfer applications where the position is fixed and accurate GPS time output is required (refer to the
CLKA/B log on Page 45 and the TM1A/B log on Page 79 for time data).
The values entered into the FIX POSITION command should reflect the precise position of the antenna’s phase centre.
Any errors in these coordinates will be propagated into the pseudorange corrections calculated by the receiver.
The height is the distance above the geoid. The Portable MEDLL receiver performs all internal computations based on
WGS-84. If you are going to input an ellipsoidal height you must first set the undulation to zero; please refer to the
UNDULATION command on Page 33.
The FIX POSITION command will override any previous FIX POSITION command settings. Use the UNFIX command
to disable the FIX POSITION setting.
Syntax:
FIX POSITION
Syntax
FIX POSITION
lat
lon
height
station id
Reference
Station Health
lat
lon
height
[Station id] [RTCM stn health]
Range Value
Description
± 90
(only 8 decimal places are shown in
the RCCA log, though higher
precision is carried internally)
± 360
(only 8 decimal places are shown in
the RCCA log, though higher
precision is carried internally)
-1,000 to 20,000,000
Command
Latitude (in degrees/decimal
degrees) of fixed monitor station
antenna in current datum. A
negative sign implies South latitude.
Longitude (in decimal degrees) of
fixed monitor station antenna in
current datum. A negative sign
implies West longitude.
Height (in metres) above the geoid
of the monitor station in current
datum.
Start-Up
Default
UNFIX
Parameter Default
Reserved
Example:
fix position 51.3455323,-114.289534,1201.123
The above example fixes the position of the receiver with fixed coordinates of:
Latitude
Longitude
Height above sea level
26
N 51° 20' 43.9163" (WGS-84 or local datum)
W 114° 17' 22.3224"
1201.123 metres
Portable MEDLL Manual Rev 1
5 – Command Descriptions
FREQUENCY_OUT
This command allows you to specify the frequency of the output pulse at the VARF pin of the I/O strobe connector. The
frequency in Hz is calculated according to the formula below. The time between pulses may have up to 49 ns jitter
variation from the true frequency pulse.
é 20473000 - 20473000
ù
(n+1)
ë
û
FREQUENCY_OUT =
(k+1)
Syntax:
k
frequency_out
n
frequency_out
disable
OR
Syntax
Range Value
Description
Default
Example
FREQUENCY_OUT
n
k
1 to 65535
1 to 65535
Command
Variable integer
Variable integer
disable
frequency_out
1
65535
Example 1:
frequency_out 1,65535
n=1, k=65535 results in an output pulse frequency of 156.196594 Hz
Example 2:
frequency_out 65535,1
n=65535, k=1 results in an output pulse frequency of 10,236,343.8034 Hz
As a reference, some n and k selections and their corresponding frequency outputs are listed in the following table:
n
1
65535
20472
1569
346
74
58
1
1
65535
k
Frequency_Out (Hz)
65535
65535
20471
2045
345
201
57
9
1
1
156.1966
312.3884
1 000.0000
9 999.9804
59 000.0000
100 000.1320
347 000.0000
1 023 650.0000
5 118 250.0000
10 236 343.8034
(Minimum)
(Maximum)
If the 49 ns jitter is not suitable for your application, the following formula may be used to eliminate the jitter.
FREQUENCY_OUT =
where:
20473000
(k+1)
N is constrained to 0, and K = 1 to 65535
NOTE: Frequency resolution of this method is not as fine as the original formula but provides jitter-free pulses.
Portable MEDLL Manual Rev 1
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5 – Command Descriptions
LOG
Many different types of data can be logged using several different methods of triggering the log events. Every log
element should be directed to a COM port. The ONTIME trigger option requires the addition of the period parameter and
optionally allows input of the offset parameter. See the beginning of Chapter 7 for further information about the ASCII
and binary data log structures.
The ‘port’ parameter is optional. If ‘port’ is not specified, ‘port’ is defaulted to the port that the command was received
on. This feature eliminates the need for you to know which port you are communicating on if you want logs to come back
to you on the same port by which you are sending commands.
If the LOG syntax does not include a ‘trigger’ type, it will be output only once following execution of the LOG
command. If ‘trigger’ type is specified in the LOG syntax, the log will continue to be output based on the ‘trigger’
specification.
The optional parameter ‘hold’ will prevent a log from being removed when the UNLOGALL command is issued. To
remove a log which was invoked using the ‘hold’ parameter requires the specific use of the UNLOG command.
The COM1 and COM2 ports allow two-way communications. Thus, you would enter COM1 as the port name.
Specific logs can be disabled using the UNLOG command, whereas all enabled logs will be disabled by using the
UNLOGALL command (except for those issued with the ‘hold’ parameter).
When the LOG command is ONTIME the software will attempt to output the log with the period chosen. The start of the
period is the 1PPS signal. For Portable MEDLL the period will be 1 second, therefore, ONTIME 1 will cause logs to be
output as soon as the data is available after the 1PPS. The OFFSET option is used to output the log with the period
starting, not from the 1PPS but, at 1PPS plus the offset. The OFFSET option value is limited by the measurement
frequency. That is, the software will only output a log after a measurement is taken. MEDLL's measurement frequency is
5 Hz. MEDLL's measurement log can be output at 1PPS plus the offset where the offset is one of 0.2, 0.4, 0.6 and 0.8
seconds. If you ask for 1PPS + 0.5 seconds, you will get data at 1PPS + 0.6 seconds. This measurement data is from the
1PPS + 0.6 measurement and not from the time of the 1PPS.
Examples:
log com1,etsb,ontime,60,1
log com1 etsb
log etsb ontime 60 1
The first example will cause the ETSB log to be sent to COM port 1, recurring every 60 seconds, and offset by 1 second.
The second example will cause the ETSB log to be sent only once, by omitting the trigger option. The third example is
identical to the first, since the only port on the Portable MEDLL receiver to which one can issue commands is configured
as COM1.
28
Portable MEDLL Manual Rev 1
5 – Command Descriptions
Syntax:
LOG
[port] datatype
Syntax
LOG
port
datatype
trigger
Range Value
Period
1-3600
Offset
0 to (period – 1)
Hold
[trigger]
[period]
Description
(Optional) COM1 is the only valid entry
Enter one of the valid data log names (see Chapter 7)
ONCE
Immediately logs the selected data to the selected port once.
Default if trigger field is left blank.
ONMARK
Logs the selected data when a MARKIN electrical event is
detected. Outputs internal buffers at time of mark – does not
extrapolate to mark time.
ONNEW
Logs the selected data each time the data is new even if the data is
unchanged.
ONCHANGED
Logs the selected data only when the data has changed.
ONTIME[period],[offset]
Immediately logs the selected data and then periodically logs the
selected data at a frequency determined by the period and offset
parameters. The logging will continue until an UNLOG command
pertaining to the selected data item is received (see UNLOG
Command, on Page 34).
CONTINUOUSLY
Will log the data all the time. The GPSCard will generate a new log
when the output buffer associated with the chosen port becomes
empty.
This may cause unpredictable results if more than one log is
assigned to the port.
The continuously option was designed for use with differential
corrections over low bit rate data links. This will provide optimal
record generation rates. The next record will not be generated until
the last byte of the previous record is loaded into the output buffer
of the UART.
(Optional) Use only with the Ontime trigger. Units for this
parameter are seconds. The selected period may be any value from
1 second to 3600 seconds. Selected data is logged immediately
and then periodic logging of the data will start at the next even
multiple of the period. If the period is 15 seconds, then the logger
will log the data when the receiver time is at even 1/4 minute marks.
The same rule applies even if the chosen period is not divisible into
its next second or minute marks. If a period of 7 seconds is chosen,
then the logger will log at the multiples of 7 seconds less than 60,
that is, 7, 14, 21, 28, 35, 42, 49, 56 and every 7 seconds thereafter.
(Optional) Use only with the Ontime trigger and with Period. Units
for this parameter are seconds. It provides the ability to offset the
logging events from the above start-up rule. If you wished to log
data at 1 second after every minute you would set the period to 60
seconds and the offset to 1 second. The default is 0.
(Optional) Prevents a log from being removed when the
UNLOGALL command is issued; UNLOG must be used.
Portable MEDLL Manual Rev 1
Start-Up Default
UNLOGALL
Parameter Default
COM1
ONCE
29
5 – Command Descriptions
RESET
This command performs a CPU reset. Following a RESET command, the Portable MEDLL receiver will initiate a coldstart boot up. Therefore, the receiver configuration will revert to the factory default.
The RESET command does not reset the clock card.
Syntax:
RESET
30
Portable MEDLL Manual Rev 1
5 – Command Descriptions
$SETFRAMETYPE
This command controls the type of navigation frame data that is output in the FRMA/B logs.
Syntax:
type
$SETFRAMETYPE
Syntax
Range Value
Description
Start-Up Default
-
Command
Individual navigation frame data can be
entered or the ‘all’ keyword can be used if the
all types are needed.
ALL
$SETFRAMETYPE
Type
ALL
GPS
GEO
Example:
$setframetype gps
Portable MEDLL Manual Rev 1
31
5 – Command Descriptions
UNASSIGN
This command cancels a previously issued ASSIGN command and the channel reverts to automatic control. If an L1
channel has reached channel tracking state 4 (L1 steady state tracking, see Table 4, Page 53), the satellite being tracked
will not be dropped when the UNASSIGN command is issued unless it is below the elevation cut-off angle and there are
healthy satellites above the elevation cut-off angle that are not already assigned to other channels.
Syntax:
UNASSIGN
Syntax
UNASSIGN
Channel
channel
Range Value
Description
Start-Up Default
0 - highest channel number
Command
Reset channel to automatic search and acquisition mode
N/A
Example:
unassign 11
UNASSIGNALL
This command cancels all previously issued ASSIGN commands for all channels. Tracking and control for each channel
reverts to automatic mode. If any of the L1 channels has reached channel tracking state 4 (L1 steady state tracking, see
Table 4, Page 53), the satellites being tracked will not be dropped when the UNASSIGNALL command is issued unless
they are below the elevation cut-off angle and there are healthy satellites above the elevation cut-off angle that are not
already assigned to other channels.
Syntax:
UNASSIGNALL
$UNASSIGNG2TOPRN
This command deletes a G2 delay assignment for a particular PRN from the user-defined table. It reverses a previous
$ASSIGNG2TOPRN command. There are two syntactical forms, as shown below.
Syntax #1:
$UNASSIGNG2TOPRN
Syntax
$UNASSIGNG2TOPRN
Prn
prn
Range Value
1 – 999
Description
Command
PRN Number
Start-Up Default
N/A
Example:
$unassigng2toprn 101
Syntax #2:
$UNASSIGNG2TOPRN
Syntax
$UNASSIGNG2TOPRN
Keyword
Keyword
Range Value
Description
Start-Up Default
ALL
Command
Keyword - 'all' is the only defined keyword at this
time.
N/A
Example:
$unassigng2toprn all
32
Portable MEDLL Manual Rev 1
5 – Command Descriptions
UNDULATION
This command permits you to either enter a specific geoidal undulation value or use the internal table of geoidal
undulations. The separation values only refer to the separation between the WGS-84 ellipsoid and the geoid at your
location, regardless of the datum chosen. When you are going to input the ellipsoidal height using the FIX POSITION
command you must first set the UNDULATION to zero.
Figure 12 illustrates the various terms used in describing height relationships. In this figure:
1 = topography
N = undulation
2 = geoid = mean sea level
h = ellipsoidal height = height above ellipsoid
3 = ellipsoid
H = height above mean sea level.
Figure 12
Height Relationships
Syntax:
UNDULATION
Separation
Syntax
Range Value
UNDULATION
Separation
Keyword “table”
or
a value
Description
Command
Selects the internal table of undulations and ignores any previously
entered value. The internal table utilizes a grid (OSU - 89B) of
approximately 1.5 degrees x 1.5 degrees.
Start-Up Default
TABLE
A numeric entry that overrides the internal table, with a value in
metres.
Examples:
undulation table
undulation -5.6
Portable MEDLL Manual Rev 1
33
5 – Command Descriptions
UNFIX
This command removes all position constraints invoked with the FIX POSITION command.
Syntax:
UNFIX
UNLOG
This command permits you to remove a specific log request from the system. It reverses the effect of a particular LOG
command.
The [port] parameter is optional. If [port] is not specified, it is defaulted to the port that the command was received on.
This feature eliminates the need for you to know which port you are communicating on if you want logs to come back on
the same port you are sending commands on.
Syntax:
UNLOG
[port] datatype
Syntax
Range Value
UNLOG
Port
datatype
COM1
any valid log
Description
Command
COM1 port from which log originated
The name of the log to be disabled
Start-Up Default
N/A
Example:
unlog com1,tm1b
UNLOGALL
This command permits you to disable all current logs on the port to which your data communication equipment is
connected. It reverses the effects of all LOG commands.
NOTE:
This command does not disable logs that have the ‘hold’ attribute (see the description for the LOG command
on Page 28). To disable logs with the ‘hold’ attribute, use the UNLOG command.
Syntax:
UNLOGALL
34
Portable MEDLL Manual Rev 1
5 – Command Descriptions
VERSION
Use this command to determine the current software version of the GPSCard. The response to the VERSION command is
logged to the port from which the command originated.
Syntax:
VERSION [all]
Response:
card type
model#
S/N MACH rev
Command
VERSION
all
date
Description
Software version of the master card
Software version of the master card and the five slave cards
Response
card type
model #
S/N
HW
MACH rev
SW
SW rev/boot code rev
date
SW rev/boot code rev
Description
Maximum Field Length
(bytes)
Card type
Model number
Serial number
Characters representing hardware (HW)
Hardware revision
Characters representing software (SW)
Firmware revision/ boot code revision
Firmware compile date
5
16
16
2
16
2
16
12
Example:
COM1>version all
Card[1] OEM-2 EGNOSMEDLL SGC00140018
Card[2] OEM-2 SGD01150132 HW 1 SW
Card[3] OEM-2 SGD01150106 HW 1 SW
Card[4] OEM-2 SGD01150105 HW 1 SW
Card[5] OEM-2 SGD01150119 HW 1 SW
Card[6] OEM-2 SGD01150118 HW 1 SW
NOTE:
HW 1 SW 5.4441S7/1.03 Sep 25/01
5.4441S7/1.03 Sep 25/01
5.4441S7/1.03 Sep 25/01
5.4441S7/1.03 Sep 25/01
5.4441S7/1.03 Sep 25/01
5.4441S7/1.03 Sep 25/01
Spaces are delimiters in between fields.
Portable MEDLL Manual Rev 1
35
6 – Output Logging
6
OUTPUT LOGGING
When outputting data from the Portable MEDLL receiver, the logs must be sent to the COM1 or COM2 serial port.
Table 2 shows the list of logs, arranged alphabetically.
Table 2
Portable MEDLL Logs Summary
Logs
9
Descriptions
Decoded almanac 5,
and A/D 6
$AGCA/B AGC
information
ALMA/B
CDSA/B
CLKA/B
B: 32
74
Latency MEDLL
108
Ave. Std. Dev.
8
88
Min
3
126
65
Max
59
15
46
147
11
18
116
138
N/A
181
75
39
02
173
N/A
10
8
466
170
3
443
53
8
492
33
100
112
61
81
15
200
118
141
5
N/A
159
3
N/A
53
110
145
33
174
58
96
54
N/A
16
N/A
178
14
03
N/A
D: 65
17
97
67
Message
ID
N/A
CRLA/B
07
8
Dilution of precision 5,
N/A
Communication and 5
differential decode status
Receiver clock offset 6
data
Correlator location in 5
C/A chips
48
DOPA/B
95
N/A
ETSA/B
Extended channel 5, 7
tracking status
Framed raw navigation 6
data
Decoded almanac-ionospheric model params.5, 9
Multipath meter 5
01
N/A
FRMA/B
MPMA/B
Computed position 5,
52
IONA/B
POSA/B
Satellite broadcast data:5
raw bits
8
RBTA/B
Receiver configuration 5
N/A
56
7
Receiver status 6
12
RCCA
Satellite Specific data 6
REPA/B Raw ephemeris 5,
Channel range 5
RGEA/B/D measurements
SATA/B
53
RVSA/B
SBTA/B
Time of 1PPS 6
Decoded almanac-UTC
time parameters 5, 9
Wide band carrier 5
range correction
Wide band code range 5
correction (inc. L1 & L2)
Satellite broadcast data:5
raw symbols
TM1A/B
UTCA/B
WBCA/B
WRCA/B
The data logs available are in NovAtel ASCII and binary format, and are described in Chapter 7. They can be logged
using several methods of triggering each log event. Each log is initiated using the LOG command. The LOG command
and syntax are described in Chapter 5; they are of the form log [port],datatype,trigger,[period],[offset],[hold].
If the LOG syntax does not include a trigger type, it will be output only once following execution of the LOG command.
If trigger type is specified in the LOG syntax, the log will continue to be output based on the trigger specification.
Specific logs can be disabled using the UNLOG command, whereas all enabled logs will be disabled by using the
UNLOGALL command unless a log has the hold attribute (see the UNLOG and UNLOGALL commands on Page 34).
The measurement rate on MEDLL is 5 Hz.
5
6
7
8
9
36
Latency of logs calculated on a receiver that has only full processing load. The log under test is logged on the receiver
under COM1. RVSB, RGEB, SFDB, FRMB and WRCB logs are logged on the receiver under COM2.
Latency of logs calculated on a receiver that has full processing and communication port load. The latency is
calculated as per the EGNOS validation test procedure. The active periodic logs are logged on the receiver under
COM1.
The footnotes that follow show the validity of logs when conditions exist.
Only valid after FINETIME is set.
Only valid after a position solution has been computed.
Only valid after the position of a complete, or partial, almanac.
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
7
NOVATEL FORMAT DATA LOGS
The Portable MEDLL receiver is capable of generating many NovAtel-format output logs, in either ASCII or binary
format.
The following log descriptions are listed in alphabetical order. Each log first lists the ASCII format, then the binary
format description.
ASCII LOG STRUCTURE
Log types ending with the letter A are output in ASCII format (e.g., POSA). The structures of all ASCII logs follow the
general conventions as noted here:
1.
The lead code identifier for each record is '$'.
2.
Each log is of variable length depending on amount of data and formats.
3.
All data fields are delimited by a comma ',' with the exception of the last data field, which is followed by a ‘*’ to
indicate end-of-message data.
4.
Each log ends with a hexadecimal number preceded by an asterisk and followed by a line termination using the
carriage return and line feed characters, e.g., *xx[CR][LF]. This 8-bit value is an exclusive OR (XOR) of all
bytes in the log, excluding the '$' identifier and the asterisk preceding the two checksum digits.
Structure:
$xxxx, data field..., data field...,
data field...
*xx [CR][LF]
BINARY LOG STRUCTURE
Log types ending with the letter B are output in binary format (e.g., POSB). The structures of the binary logs follow the
general conventions as noted here:
1.
Basic format of:
Sync
Checksum
Message ID
Message byte count
Data
2.
The Sync bytes will always be:
Byte
Hex
Decimal
First
Second
Third
AA
44
11
170
68
17
3 bytes
1 byte
4 bytes unsigned integer
4 bytes unsigned integer
x bytes
3.
The Checksum is an XOR of all the bytes, including the 12 header bytes with CRC = 00.
4.
The Message ID identifies the type of log to follow.
5.
The Message byte count equals the total length of the data block including the header.
NOTE:
Maximum flexibility for logging data is provided by these logs. You are cautioned however, to recognize that
each log requested requires additional CPU time and memory buffer space. Too many logs may result in lost
data and degraded CPU performance. Buffer overload can be monitored using the idle time and buffer
overload bits from the RVSB log. Please refer to Table 11, Receiver Self-Test Status Codes on Page 69.
Portable MEDLL Manual Rev 1
37
7 – NovAtel Format Data Logs
The following describes the format types used in the description of binary logs.
Type
Size (bytes)
Size (bits)
Description
char
1
8
int
4
32
double
8
64
float
4
32
long
4
32
The char type is used to store the integer value of a member of the representable character set.
That integer value is the ASCII code corresponding to the specified character.
The size of a signed or unsigned int item is the standard size of an integer on a particular
machine. On a 32-bit processor (such as the NovAtel GPSCard), the int type is 32 bits, or 4
bytes. The int types all represent signed values unless specified otherwise. Signed integers are
represented in two's-complement form. The most-significant bit holds the sign: 1 for negative, 0
for positive and zero.
The double type contains 64 bits: 1 for sign, 11 for the exponent, and 52 for the mantissa. Its
range is ±1.7E308 with at least 15 digits of precision.
The float type contains 32 bits: 1 for the sign, 8 for the exponent, and 23 for the mantissa. Its
range is ±3.4E38 with at least 7 digits of precision.
The long type is a 32-bit integer in the range –2147483647 to +2147483648
Each byte within an int has its own address, and the smallest of the addresses is the address of the int. The byte at this
lowest address contains the eight least significant bits of the double word, while the byte at the highest address contains
the eight most significant bits. Similarly the bits of a "double" type are stored least significant byte first. This is the same
data format used by personal computers.
COMPRESSED BINARY LOG STRUCTURE
Log types ending with the letter D are also output in binary format (e.g., RGED). However, the RGED message is a
compressed form of the RGEB message.
TIME CONVENTIONS
All logs report GPS time expressed in GPS weeks and seconds into the week. The time reported is not corrected for the
local receiver’s clock error. To derive the closest GPS time, one must subtract the clock offset shown in the CLKB log
(field 4) from GPS time reported.
GPS time is based on an atomic time scale. Universal Time Coordinated (UTC) time is also based on an atomic time
scale, with an offset of seconds applied to coordinate Universal Time to GPS time. GPS time is designated as being
coincident with UTC at the start date of January 6, 1980 (00 hours) GMT. GPS time does not count leap seconds, and
therefore an offset exists between UTC and GPS time. The GPS week consists of 604800 seconds, where 000000
seconds is at Saturday midnight. Each week at this time, the week number increments by one, and the seconds into the
week resets to 0. See also the section on Compliance with GPS Week Rollover on Page viii.
LOG DESCRIPTIONS
The log references that follow are in alphabetical order as in Table 2, Portable MEDLL Logs Summary on Page 36.
For binary logs, the 32-bit CRC is calculated with all fields in the log filled except for the checksum field, which is zero.
For the ASCII logs, the 32-bit CRC is calculated from all fields of the log after the ‘$’ symbol. Once the CRC has been
calculated, the log checksum is calculated in the normal fashion, in order to preserve the standard NovAtel log format.
The GPS seconds into the week value is stored in a number of different ways within the receiver. Depending on which
log is being output, the time may be derived from a different source. However, all sources of time are interconnected.
Generally, the seconds into the week field is stored as either an integer (in milliseconds) or a floating-point value before
being output in the log.
The CRC for the Portable MEDLL logs uses the standardized IEEE 802 CRC algorithm. The expanded polynomial for
the algorithm is:
X
38
32
+ x
26
+ x
23
+ x
22
+ x
16
+ x
12
+ x
11
+ x
10
8
7
5
4
2
+ x + x + x + x + x + x + 1
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
$AGCA/B
AGC AND A/D INFORMATION
The AGCA/B log contains AGC related information. This information includes information about the AGC gain, A/D bin
values and AGC control statistics.
$AGCA
Structure:
$AGCA week seconds rec_status # RF
RF_type bin 1 bin 2 bin 3 bin 4 bin 5 bin 6
Gain 1ms_AGC 1ms_Chan
bins_rms gof_stat
:
next RF deck if required *xx
[CR][LF]
Field #
1
2
3
4
5
Field type
$AGCA
week
seconds
rec_status
# RF
6
7
8
9
10
11
12
13
14
RF_type
bin 1
bin 2
bin 3
bin 4
bin 5
bin 6
gain
1ms_AGC
15
1ms_Chan
16
bins_rms
17
gof_stat
Data Description
Log header
GPS week number
GPS seconds into the week
Self-test status of the receiver (see Table 11, Page 69)
Number of RF decks reported in this message.
0 = GPS_L1, all others are reserved for future usage.
A/D Bin 1
A/D Bin 2
A/D Bin 3
A/D Bin 4
A/D Bin 5
A/D Bin 6
AGC Gain
Estimate of the receiver noise based on an A/D data histogram. 1
ms noise floor calculated using the A/D bin values.
Estimate of the receiver noise that is either an AGC estimate or
measured power in a 1 ms post correlation accumulation from a
searching channel.
Estimate of the variance of the receiver noise based on time
smoothed A/D data histograms. Root mean squared value of the
A/D bins calculated using the expected values as truth.
The chi-squared test statistic estimating the goodness of fit
between a current A/D data histogram to an A/D data histogram that
was obtained at start-up by averaging several A/D histogram
samples. Goodness of Fit test statistic for the A/D bins.
18...29
….
Next RF Deck if required.
Variable
Variable
*xx
[CR][LF]
Checksum
Sentence terminator
Example
$AGCA
932
256542.00
43A00FF
2
0
0.1022
0.1813
0.2380
0.2363
0.1558
0.0864
3125
1557822.00
1557822.00
0.9957
0.000008
….
*66
[CR][LF]
Example:
$AGCA,932,256542.00,43A00FF,2,0,0.1022,0.1813,0.2380,0.2363,0.1558,0.0864,3125,1557822.00,1557822.00,0.995
7,0.000008,1,0.0973,0.1722,0.2353,0.2406,0.1637,0.0909,3361,1552060.00,1552060.00,0.9935,0.000042*66 [CR][LF]
Portable MEDLL Manual Rev 1
39
7 – NovAtel Format Data Logs
$AGCB
Format:
Field #
Data
Bytes
Format
1
(header)
Sync
Checksum
Message ID
Message byte count
3
1
4
4
Char
Char
Integer
Integer
bytes
2
3
4
5
Week number
Time of week
Receiver status
No. of RF decks
4
8
4
4
Integer
Double
Integer
Integer
weeks
seconds
(See Table 11, Page 69)
number of receiver RF decks
12
16
24
28
6
RF Type
4
Integer
32
A/D Bin 1 (Most Neg.)
A/D Bin 2
A/D Bin 3
A/D Bin 4
A/D Bin 5
A/D Bin 6 (Most Pos.)
AGC Gain
1ms Noise Floor From AGC
1ms Noise Floor From Channels
A/D Bins RMS
A/D Goodness of Fit Test Statistic
Next RF Deck if required
4
4
4
4
4
4
4
4
4
4
4
48
Float
Float
Float
Float
Float
Float
Integer
Float
Float
Float
Float
0 = GPS_L1, all others are reserved
for future usage.
percentage
percentage
percentage
percentage
percentage
percentage
0 to 99,999 (0 is max)
7
8
9
10
11
12
13
14
15
16
17
18...29
40
Message ID = 74
Message byte count = 32 + (r * 48) where r is the # of RF decks.
Units
Offset
0
3
4
8
36
40
44
48
52
56
60
64
68
72
76
80
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
ALMA/B DECODED ALMANAC
This log contains the decoded almanac parameters from sub-frames four and five as received from the satellite with the
parity information removed and appropriate scaling applied. Multiple messages are transmitted, one for each SV almanac
collected.
The Ionospheric Model parameters (IONA/B) and the UTC Time parameters (UTCA/B) are also provided, following the
last almanac record. These cannot be logged individually or independently of the ALMA/B message. They are, however,
described separately under their respective names.
For more information on Almanac data, refer to the GPS SPS Signal Specification.
NOTE:
In order to limit CPU loading while decoding the almanac, all almanac data is decoded from a single tracked
satellite, arbitrarily chosen among all tracking channels.
ALMA
Structure:
$ALMA
A
Prn ecc
incl-angle
Field #
1
2
3
4
5
6
7
8
9
10
seconds
health-4
Field type
$ALMA
prn
ecc
seconds
week
w
ra
w
Mo
week
w
health-5
ra
w
Mo
health-alm
af0 af1 cor-mean-motion
*xx [CR][LF]
Data Description
Log header
Satellite PRN number for current message (1-32)
Eccentricity
Almanac reference time, seconds into the week
Almanac reference week (GPS week number)
Rate of right ascension, radians
Right ascension, radians
Argument of perigee, radians
Mean anomaly, radians
Clock aging parameter, seconds
11
af0
af1
12
13
14
15
16
17
18
19
cor-mean-motion
A
incl-angle
health-4
health-5
health-alm
*xx
[CR][LF]
Corrected mean motion, radians/second
Semi-major axis, metres
Angle of inclination, radians
Anti-spoofing and SV config from sub-frame 4, page 25
SV health, 6 bits/SV (sub-frame 4 or 5, page 25)
SV health, 8 bits (almanac)
Checksum
Sentence terminator
$ALMA
$IONA
$UTCA
Last satellite PRN almanac message
Ionospheric Model Parameters
UTC Time Parameters
Clock aging parameter, seconds/second
Example
$ALMA
1
3.55577E-003
32768
745
-7.8860E-009
-6.0052951E-002
-1.1824254E+000
1.67892137E+000
-1.8119E-005
-3.6379E-012
1.45854965E-004
2.65602281E+007
9.55576E-001
1
0
0
*20
[CR][LF]
:
1 - 19
1 - 11
1 - 11
Portable MEDLL Manual Rev 1
41
7 – NovAtel Format Data Logs
Example:
$ALMA,1,4.99010E-003,503808,67,-7.8975E-009,5.58933014E-001,-1.7435100E+000,
-1.3147095E+000,1.55449E-004,0.00000E+000,1.45861599E-004,2.65594229E+007,
9.62689E-001,1,0,0*22[CR][LF]
…
$ALMA,31,9.92775E-003,503808,67,-8.1832E-009,-2.6301490E+000,8.33547783E-001,
-2.8544401E-001,2.19345E-005,0.00000E+000,1.45849203E-004,2.65609277E+007,
9.47985E-001,1,0,0*19[CR][LF}
$IONA,2.3283064365386962E-008,0.0000000000000000E+000,-1.192092895507812E-007,
1.1920928955078122E-007,1.4336000000000018E+005,-1.966080000000002E+005,0.
0000000000000000E+000,1.9660800000000019E+005*0A[CR][LF]
$UTCA,1.8626451492309570E-008,2.8421709430404010E-014,503808,67,990,13,13,
5*05[CR][LF]
ALMB
Format:
Field #
1
(header)
42
Message ID = 18
Message byte count = 120
Field Type
Sync
Checksum
Message ID
Message byte count
Bytes
3
1
4
4
Format
Units
integer
bytes
Offset
0
3
4
8
integer
double
double
integer
double
double
double
double
double
dimensionless
dimensionless
seconds
weeks
radians/second
radians
radians
radians
seconds
12
16
24
32
36
44
52
60
68
2
3
4
5
6
7
8
9
10
Satellite PRN number
Eccentricity
Almanac ref. time
Almanac ref. week
Rate of right ascension
Right ascension
Argument of perigee
Mean anomaly
Clock aging parameter
w
Mo
af0
4
8
8
4
8
8
8
8
8
11
Clock aging parameter
af1
8
double
seconds/second
76
12
13
14
15
16
17
Corrected mean motion
Semi-major axis
Angle of inclination
SV health from sub-frame 4
SV health from sub-frame 4 or 5
SV health from almanac
8
8
8
4
4
4
double
double
double
integer
Integer
Integer
radians/second
metres
radians
84
92
100
108
112
116
w
A
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
CDSA/B
COMMUNICATION AND DIFFERENTIAL DECODE STATUS
The Portable MEDLL receiver maintains a running count of a variety of status indicators of the data link. This log
outputs a report of those indicators.
Parity and framing errors will occur if poor transmission lines are encountered or if there is an incompatibility in the data
protocol. If errors occur, you may need to confirm the baud rate, number of data bits, number of stop bits, and parity of
both the transmitting and receiving ends. Overrun errors will occur if more characters are sent to the UART than can be
removed by the on-board microprocessor.
CDSA
Structure:
$CDSA
Xon2
Res’d
Res’d
Field #
1
2
3
4
5
week seconds
cts2 parity2
Res’d
Res’d
Res’d
Res’d
Field type
$CDSA
week
seconds
xon1
cts1
6
7
8
9
10
11
parity1
overrun1
framing1
rx1
tx1
xon2
12
cts2
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
parity2
overrun2
framing2
rx2
tx2
xon1 cts1 parity1 overrun1 framing1
rx1 tx1
overrun2
framing2 rx2 tx2
Res’d Res’d
Res’d
Res’d Res’d
Res’d Res’d
*xx
[CR][LF]
Data Description
Log header
GPS week number
GPS seconds into the week
Flag to indicate that the com1 is using XON/XOFF handshaking protocol and port has received an
XOFF and will wait for an XON before sending any more data.
Flag to indicate that com1 is using CTS/RTS handshake protocol and CTS line port has been
asserted. The port will wait for the line to de-assert before sending any more data.
A running count of character parity errors from the UART of COM1
A running count of UART buffer overrun errors of COM1
A running count of character framing error from the UART of COM1
A running count of the characters received from COM1
A running count of the characters sent out COM1
Flag to indicate that the COM2 is using XON/XOFF handshaking protocol and port has received an
XOFF and will wait for an XON before sending any more data.
Flag to indicate that COM2 is using CTS/RTS handshake protocol and CTS line port has been
asserted. The port will wait for the line to de-assert before sending any more data.
A running count of character parity errors from the UART of COM2
A running count of UART buffer overrun errors of COM2
A running count of character framing error from the UART of COM2
A running count of the characters received from COM2
A running count of the characters sent out COM2
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Portable MEDLL Manual Rev 1
Example
$CDSA
787
500227
0
0
0
0
0
0
9
0
0
0
0
0
0
9
0
0
0
0
0
0
0
0
0
0
0
0
0
43
7 – NovAtel Format Data Logs
Field #
31
32
Example:
Field type
Data Description
*xx
Checksum
[CR][LF]
Sentence terminator
$CDSA,787,500227,0,0,0,0,0,0,9,0,0,0,0,0,0,9,0,0,0,0,0,0,0,0,0,0,0,0,0*33[CR][LF]
Example
*33
[CR][LF]
CDSB
Format:
Message ID = 39
Field #
1
(header)
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Data
Message byte count = 128
Bytes
Format
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
Units
bytes
Week number
Time of week
Xon COM1
CTS COM1
Parity errors COM1
Overrun errors COM1
Framing error COM1
Bytes received in COM1
Bytes sent out COM1
Xon COM2
CTS COM2
Parity errors COM2
Overrun errors COM2
Framing error COM2
Bytes received in COM2
Bytes sent out COM2
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
Reserved. Set to 0.
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
integer
weeks
seconds
1 or 0
1 or 0
Total count
Total count
Total count
Total count
Total count
1 or 0
1 or 0
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Total count
Offset
0
3
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
68
72
76
80
84
88
92
96
100
104
108
112
116
120
124
4
44
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
CLKA/B RECEIVER CLOCK OFFSET DATA
This log is used to monitor the state of the receiver time. Its values will depend on the CLOCKADJUST command. If
CLOCKADJUST is enabled, then the offset and drift times will approach zero. If not enabled, then the offset will grow at
the oscillator drift rate. Disabling CLOCKADJUST and monitoring the CLKA/B log will allow you to determine the
error in your GPSCard receiver reference oscillator as compared to the GPS satellite reference.
All logs report GPS time not corrected for local receiver clock error. To derive the closest GPS time, you must subtract
the clock offset (field #4 of the CLKA log) from the reported GPS time.
Field #6 is the output of a Gauss-Markov Selective Availability clock dither estimator. This value reflects both the
collective SA-induced short-term drift of the satellite clocks, when SA is active, as well as any range bias discontinuities
that would normally affect the clock model’s offset and drift states. With SA off this value is much smaller than the
example shown.
The CLKA/B log is not synchronous to the 1PPS.
Clock model status is not related to clock type. There is no effect on the validity of the clock model data when the
CLOCKADJUST command is set to DISABLE. Upon receiver start-up, the data in the CLKA/B log is not valid. After a
position-time solution this log will show the difference between the 1PPS and GPS epoch. The CM STATUS field shows
the current stability of the clock model. If CLOCKADJUST is disabled, CM STATUS is meaningless. CLOCKADJUST
is disabled by default for Portable MEDLL.
The internal units of the clock model’s three states (offset, drift and GM state) are meters, meters per second, and meters.
When scaled to time units for the output log, these become seconds, seconds per second, and seconds, respectively.
CLKA
Structure:
$CLKA
week
seconds
offset
drift
G-M state
offset std
drift std cm status
*xx [CR][LF]
Field #
1
2
3
4
Field type
$CLKA
week
seconds
offset
5
drift
6
7
8
9
G-M state
offset std
drift std
cm status
10
11
*xx
[CR][LF]
Data Description
Log header
GPS week number
GPS seconds into the week
Receiver clock offset (s). A positive offset implies that the receiver clock is ahead of
GPS Time. To derive GPS time, use the following formula:
GPS time = receiver time – (offset)
Receiver clock drift (s/s). A positive drift implies that the receiver clock is running faster
than GPS Time.
The output value of the Gauss-Markov Selective Availability clock dither estimator (s).
Standard deviation of receiver clock offset (s).
Standard deviation of receiver drift (s/s)
Receiver Clock Model Status (0 = valid, -20 to -1 imply that the model is in the process
of stabilization)
Checksum
Sentence terminator
Example
$CLKA
637
511323.00
-4.628358547E-003
-2.239751396E-007
2.061788299E-006
5.369997167E-008
4.449097711E-009
0
*7F
[CR][LF]
Example:
$CLKA,841,499296.00,9.521895494E-008,-2.69065747E-008,2.061788299E-006,
9.642598169E-008,8.685638908E-010,0*4F[CR][LF]
Portable MEDLL Manual Rev 1
45
7 – NovAtel Format Data Logs
CLKB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
9
46
Message ID = 02
Message byte count = 68
Field Type
Sync
Checksum
Message ID
Message byte count
Bytes
3
1
4
4
Format
char
char
integer
integer
Week number
Seconds of week
Clock offset
Clock drift
SA Gauss-Markov state
StdDev clock offset
StdDev clock drift
Clock model status
4
8
8
8
8
8
8
4
integer
double
double
double
double
double
double
integer
Units
bytes
weeks
s
s
s/s
s
s
s/s
0 = good, -1 to -20 = bad
Offset
0
3
4
8
12
16
24
32
40
48
56
64
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
CRLA/B CORRELATOR LOCATION IN C/A CHIPS
It is recommended that this be output only ‘once’ or ‘ontime’. The ‘onnew’ and ‘onchanged’ options have been disabled.
The order that the correlator locations are output is identical to the order of the residuals in the MPMA/B (multipath
meter) log.
CRLA
Structure:
$CRLA
…
$CRLA
Field #
1
2
3
4
5
6
7
18
19…
variable
variable
week
sec #chans chan#
#corr
1
st
corr
…
12
th
corr
week
sec #chans chan#
#corr
1
st
corr
…
12
th
corr
Field Type
$CRLA
Week Number
Seconds of Week
Number of Channels
Channel Number
Number of Correlators
1st correlator location
…
12th correlator location
5 – 19 Repeated for # of Channels
*xx
[CR][LF]
Data Description
GPS week number
GPS seconds into the week
Location of correlator 1 (in C/A chips)
Repeated for each correlator
Location of correlator 12
Checksum
Sentence terminator
*xx [CR][LF]
Examples
$CRLA
2
234534.56
16
0
12
-0.04
…
1.40
…
*29
[CR][LF]
Example:
$CRLA,61,158572.947,16,
0,12,-0.15,-0.10,-0.05,0.00,0.05,0.10,0.15,0.30,0.50,0.70,0.90,1.30,
1,12,-0.15,-0.10,-0.05,0.00,0.05,0.10,0.15,0.30,0.50,0.70,0.90,1.30,
…
15,12,-0.60,-0.40,-0.20,0.00,0.20,0.40,0.60,0.80,1.00,1.20,1.40,1.60*28 [CR][LF]
Portable MEDLL Manual Rev 1
47
7 – NovAtel Format Data Logs
CRLB
Format:
Field #
1
(header)
2
3
4
5
6
7
18
19…
48
Message ID = 96
Data
Message byte count = 28+(#chans*56)
Bytes
Format
Sync
3
Char
Checksum
1
Char
Message ID
4
Integer
Message Byte Count
4
Integer
Week Number
4
Integer
Seconds of Week
8
Double
Number of Channels
4
Integer
Channel Number
4
Integer
Number of Correlators
4
Integer
1st correlator location
4
Float
…
12th correlator location
4
Float
Next channel number
Offset = 28 + (chan#*56) where chan# = 0 to (number of channels-1)
Units
Offset
C/A chips
0
3
4
8
12
16
24
28
32
36
C/A chips
80
bytes
weeks
seconds
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
DOPA/B DILUTION OF PRECISION
The dilution of precision data is calculated using the geometry of only those satellites that are currently being tracked and
used in the position solution by the GPSCard and updated once every 60 seconds. Therefore, the total number of data
fields output by the log is variable, depending on the number of satellites being tracked. Twelve is the maximum number
of satellite PRNs contained in the list.
NOTE:
If insufficient satellites are being tracked to calculate DOP values, the last calculated DOP values are output.
DOPA
Structure:
$DOPA
Field #
1
2
3
4
week
sec gdop
Field type
$DOPA
week
sec
gdop
5
pdop
6
7
8
htdop
hdop
tdop
9
10...
variable
variable
#sats
prns
*xx
[CR][LF]
pdop
htdop
hdop
tdop
#sats
prns
*xx [CR][LF]
Data Description
Log header
GPS week number
GPS seconds into the week
Geometric dilution of precision - assumes 3-D position and receiver clock offset (all 4
parameters) are unknown
Position dilution of precision - assumes 3-D position is unknown and receiver clock offset is
known
Horizontal position and time dilution of precision
Horizontal dilution of precision
Time dilution of precision - assumes 3-D position is known and only receiver clock offset is
unknown
Number of satellites used in position solution (0-12). See the notes above.
PRN list of SV PRNs tracking (1-32), null field until first position solution available
Checksum
Sentence terminator
Example
$DOPA
637
512473.00
2.9644
2.5639
2.0200
1.3662
1.4880
6
18,6,11,2,16,19
*29
[CR][LF]
Example:
$DOPA,637,512473.00,2.9644,2.5639,2.0200,1.3662,1.4880,6,18,6,11,2,16,19
*29[CR][LF]
Portable MEDLL Manual Rev 1
49
7 – NovAtel Format Data Logs
DOPB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
9
10
11...
50
Message ID = 07
Data
Sync
Checksum
Message ID
Message byte count
Message byte count = 68+(#sats*4)
Bytes
3
1
4
4
Format
char
char
integer
integer
Week number
4
integer
Seconds of week
8
double
gdop
8
double
pdop
8
double
htdop
8
double
hdop
8
double
tdop
8
double
Number of satellites used
4
integer
1st PRN
4
integer
Next satellite PRN
Offset = 68 + (sats*4) where sats = 0 to (number of sats-1)
Units
bytes
weeks
seconds
Offset
0
3
4
8
12
16
24
32
40
48
56
64
68
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
ETSA/B EXTENDED CHANNEL TRACKING STATUS
These logs provide channel tracking status information for each of the GPSCard parallel channels.
NOTE:
This log is intended for status display only; since some of the data elements are not synchronized together,
they are not to be used for measurement data. Please use the RGEA/B/D and SATA/B logs to obtain
synchronized data for post processing analysis.
As shown in Table 4 (Channel Tracking Status word), bit 19 shows the observation is for L1. This is to aid in parsing the
data.
ETSA
Structure:
$ETSA week
seconds
sol status # obs
prn ch tr-status dopp C/No residual locktime psr reject code
:
prn ch tr-status dopp C/No residual locktime psr reject code
Field #
1
2
3
4
5
6
7
sol status
# obs
prn
ch tr-status
8
9
10
11
12
13
dopp
C/No
residual
locktime
psr
reject code
14-21
..
94-101
102
103
10
Field type
$ETSA
week
seconds
*xx [CR][LF]
Data Description
Log header
GPS week number
GPS seconds into the week (receiver time, not corrected for clock
error, CLOCKADJUST enabled)
Solution status (see Table 3, on Page 53)
Number of observations to follow
Satellite PRN number (1-32) (channel 0) 10
Hexadecimal number indicating channel tracking status (See Table 4,
on Page 53)
Instantaneous carrier Doppler frequency (Hz)
Carrier to noise density ratio (dB-Hz)
Residual from position filter (m)
Number of seconds of continuous tracking (no cycle slips)
Pseudorange measurement (m)
Indicates whether the range is valid (code = 0) or not (see Table 7, on
Page 54)
..
..
..
next observation
..
last observation
*xx
[CR][LF]
Checksum
Sentence terminator
Example
$ETSA
850
332087.00
0
24
7
00082E04
-613.5
54.682
27.617
12301.4
20257359.57
0
*19
[CR][LF]
Satellite PRN = 0 if the channel is idle.
Portable MEDLL Manual Rev 1
51
7 – NovAtel Format Data Logs
Example (carriage returns have been added between observations for clarity):
$ETSA,850,332087.00,0,24,
7,00082E04,-613.5,54.682,27.617,12301.4,20257359.57,0,
7,00582E0B,-478.1,46.388,0.000,11892.0,20257351.96,13,
5,00082E14,3311.2,35.915,1.037,1224.4,24412632.47,0,
5,00582E1B,2580.4,39.563,0.000,1186.7,24412629.40,13,
9,00082E24,1183.1,53.294,-29.857,7283.8,21498303.67,0,
9,00582E2B,921.9,44.422,0.000,7250.2,21498297.13,13,
2,00082E34,-2405.2,50.824,-20.985,19223.6,22047005.47,0,
2,00582E3B,-1874.1,41.918,0.000,19186.7,22046999.44,13,
4,00082E44,3302.8,47.287,7.522,3648.1,22696783.36,0,
4,00582E4B,2573.6,37.341,0.000,3191.2,22696778.15,13,
14,00082E54,2132.7,41.786,-22.388,541.3,25117182.07,0,
14,00582E5B,1661.7,33.903,0.000,500.7,25117179.63,13,
26,00082E64,-3004.3,43.223,2.928,14536.2,25074382.19,0,
26,00582E6B,-2340.9,33.019,0.000,14491.7,25074378.01,13,
15,00082E74,-3037.7,43.669,0.508,12011.5,24104788.88,0,
15,00582E7B,-2367.0,34.765,0.000,11842.4,24104781.53,13,
24,00082E84,3814.0,37.081,7.511,95.7,25360032.49,0,
24,00582E8B,2972.0,24.148,0.000,5.2,25360030.13,13,
28,00082A90,-9800.9,0.000,0.000,0.0,0.00,9,
28,00382A90,-7637.0,0.000,0.000,0.0,0.00,9,
3,000822A0,-3328.3,0.000,0.000,0.0,0.00,9,
3,005828A0,-2593.5,0.000,0.000,0.0,0.00,9,
27,000822B0,-3851.7,0.000,0.000,0.0,0.00,9,
27,005828B0,-3001.7,0.000,0.000,0.0,0.00,9
*41[CR][LF]
ETSB
Format:
Field #
Bytes
Format
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
2
3
4
5
Week number
Time of week
Solution status
No. of channels
4
8
4
4
integer
double
integer
integer
weeks
seconds
(See Table 3, on Page 53)
number of channels in receiver
12
16
24
28
6
7
8
9
PRN number (chan 0)
Channel tracking status
Doppler
C/N0 (db-Hz)
4
4
8
8
integer
integer
double
double
(See Table 4, on Page 53)
Hz
db Hz
32
36
40
48
1
(header)
10
11
12
13
14 ...
52
Message ID = 48
Message byte count = 32 + (n*52) where n is number of channels in receiver
Data
Units
Offset
0
3
4
8
bytes
Residual
8
double
metres
Locktime
8
double
seconds
Pseudorange
8
double
metres
Rejection code
4
integer
(See Table 7, on Page 54)
Offset = 32 + (chan * 52) where chan varies from 0 - highest channel number
56
64
72
80
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
Table 3
Value
0
1
2
3
4
5
6
GPSCard Solution Status
Description
Solution computed
Insufficient observations
No convergence
Singular AtPA Matrix
Covariance trace exceeds maximum (trace > 1000 m)
Test distance exceeded (maximum of 3 rej if distance > 10 Km)
Not yet converged from cold start
Higher numbers are reserved for future use
Table 4
N 7
N 6
N 5
N 4
N 3
Channel Tracking Status Bits
N 2
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
N 1
8
7
6
5
N 0
4
3
2
1
0
<- <- Nibble Number
Bit
Description
Range Values
lsb =0
Hex.
1
1 Tracking st at e
0 - 11 See below
2
2
4
3
8
4
10
5
0 - n (0 =f irst, n =last )
6 Channel number
(n dependson GPSCard model) 40
20
7
80
8
100
8
9 Phase lock f lag
8
10 Parity known f lag
11 Code locked f lag
8
1=Lock, 0 =Not locked
200
1=Known, 0 =Not known
400
1=Lock, 0 =Not locked
800
12
1000
13 Correlat or spacing t ype 0 - 7 See t he Correlat or
2000
14
Spacing Table 1
4000
15
0=GPS 3=Reserved
8000
16 Sat ellite syst em
1=Reserved 4-7 Reserved
10000
17
2=GEO2
20000
18 Ant enna
1=Secondary, 0 =Primary 3
40000
4
19 Grouping
1=Grouped, 0 =Not grouped
80000
1=L2, 0 =L1
100000
0 =C/ A 2 =P-codeless
200000
5
20 Frequency
21 Code type
6
22
1=P
3 =Reserved
7
23 Forward error correct ion 1=FECenabled, 0 =no FEC
400000
800000
24
: Reserved. Set t o 0.
29
30 Ext ernal range
1=Ext . range, 0 =Int . range
31 Channel assignment
1=Forced, 0 =Aut omatic
1 See Table 5, Bits 12-14: Correlator Spacing on Page 54.
2 GEO will never be set for MEDLL channels 0-9
3 Antenna will always be primary
4 MEDLL is always 0
5 MEDLL is always 0
6 MEDLL is always 0
7 MEDLL channels 10-11 will be 1 and MEDLL channels 0-9 will be 0.
8 When phase, parity, and code lock have been established, the channel has reached steady state tracking in state 4.
Portable MEDLL Manual Rev 1
53
7 – NovAtel Format Data Logs
Table 5
Value of Bits 0-3
Bits 0 - 3 : Channel Tracking State
Description
Value of Bits 0-3
0
L1 Idle (State 0)
1
L1 Sky search (State 1)
2
L1 Dual frequency band pull-in (State 2)
3
L1 Narrow frequency band pull-in (State 3)
4
L1 Steady state tracking (State 4)
5
L1 Re-acquisition (State 5)
Higher numbers are reserved for future use
Table 6
Description
Reserved. (State 6)
L1 Frequency-lock loop (State 7)
Reserved
Bits 12-14 : Correlator Spacing
State
0
1
2
3
4
5
6
7
8
9
10
11
Description
Unknown: this only appears in versions of software previous to x.4x, which didn’t use this field
Standard correlator: spacing = 1 chip
Reserved
MET: uses Early-Late Slope Technique to improve correlator performance in reducing errors due to multipath
Reserved.
MEDLL: decomposes the incoming signal into direct-path and reflected-path components to reduce errors due to multipath
Higher numbers are reserved for future use
Table 7
Value
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Range Reject Codes
Description
Observations are good
Bad satellite health is indicated by ephemeris data
Old ephemeris due to data not being updated during last 3 hours
Eccentric anomaly error during computation of the satellite’s position
True anomaly error during computation of the satellite’s position
Satellite coordinate error during computation of the satellite’s position
Elevation error due to the satellite being below the cut-off angle
Misclosure too large due to excessive gap between estimated and actual positions
No differential correction is available for this particular satellite
Ephemeris data for this satellite has not yet been received
Invalid IODE due to mismatch between differential stations
Locked out of the position solution by the user
Low Power: satellite rejected due to low signal/noise ratio
Reserved.
GEO satellite not used in the position filter for Portable MEDLL
Higher numbers are reserved for future use
54
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
FRMA/B FRAMED RAW NAVIGATION DATA
This message contains the raw framed navigation data. An individual message is sent for each PRN being tracked. The
message is updated with each new frame, therefore it is best to log the data with the ‘onnew’ trigger activated.
The types of navigation frame data which are output by this log are defined using the $SETFRAMETYPE command.
NOTES: The most significant bits of the data in the message will be padded with zeroes in order to fill the last
complete data byte.
When the raw framed navigation data is output from the receiver, any bit errors encountered will have been
corrected.
FRMA
$FRMA
*xx
week
seconds
prn cstatus
# of bits framed raw data
[CR][LF]
Field #
1
2
3
4
5
6
Field type
$FRMA
week
seconds
prn
cstatus
# of bits
7
framed raw data
Data Description
Log header
GPS week number
GPS seconds into the week
PRN of satellite from which data originated
Channel Tracking Status
Number of bits transmitted in the message.
250 for GEO, 300 for GPS
One field of raw framed navigation data
8
9
*xx
[CR][LF]
Checksum
Sentence terminator
Example
$FRMA
845
238623.412
120
80811F14
250
9AFE5354656C2053796E6368726F6E69636974792020202020
202020B0029E40
*3F
[CR][LF]
Example:
$FRMA,845,238623.412,120,80811F14,250,
9AFE5354656C2053796E6368726F6E69636974792020202020202020B0029E40*3F[CR][LF]
Data transmitted by the SV in this example is hexadecimal 9AFE5354656C2053796E6368726F6E6963697479
2020202020202020B0029E plus 2 bits (01) with the bit on the left sent first. The receiver outputs the log as hexadecimal
9AFE5354656C2053796E6368726F6E69636974792020202020202020B0029E plus hexadecimal 40 (binary 01 with 6
zeroes of padding ® 01000000).
FRMB
Format:
Message ID = 54
Message byte count = variable
Field #
Data
Bytes
Format
1
(header)
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
bytes
4
8
4
4
4
32 for GEO; 38 for GPS
integer
double
integer
integer
integer
char
weeks
seconds
1-999
N/A
250 for GEO; 300 for GPS
N/A
2
3
4
5
6
7
Week number
Seconds of week
PRN number
Channel Status
Number of Bits
Data Sub-frame
Portable MEDLL Manual Rev 1
Units
Offset
0
3
4
8
12
16
24
28
32
36
55
7 – NovAtel Format Data Logs
IONA/B DECODED ALMANAC - IONOSPHERIC MODEL PARAMETERS
The Ionospheric Model parameters (IONA/B) are provided following the last almanac records when an ALMA/B
message has been logged. The IONA/B message cannot be logged individually or independently of the ALMA/B
message.
For more information on Almanac data, refer to the GPS SPS Signal Specification11.
IONA
Structure:
$IONA
Field #
1
2
3
4
act a1ot
a2ot
Field type
$IONA
act
a1ot
a2ot
5
a3ot
6
7
8
bct
b1ot
b2ot
9
b3ot
10
11
*xx
[CR][LF]
a3ot
bct
b1ot
b2ot
Data Description
b3ot
*xx [CR][LF]
Example
Log header
Alpha constant term, seconds
Alpha 1st order term, sec/semicircle
Alpha 2nd order term, sec/(semic.)2
$IONA
1.0244548320770265E-008
1.4901161193847656E-008
-5.960464477539061E-008
Alpha 3rd order term, sec/(semic.)3
Beta constant term, seconds
Beta 1st order term, sec/semicircle
Beta 2nd order term, sec/(semic.)2
-1.192092895507812E-007
Beta 3rd order term, sec/(semic.)3
Checksum
Sentence terminator
8.8064000000000017E+004
3.2768000000000010E+004
-1.966080000000001E+005
-1.966080000000001E+005
*02
[CR][LF]
Example:
$IONA,1.0244548320770265E-008,1.4901161193847656E-008,-5.960464477539061E-008,
-1.192092895507812E-007,8.8064000000000017E+004,3.2768000000000010E+004,
-1.966080000000001E+005,-1.966080000000001E+005*02[CR][LF]
11
56
For copies of the Interface Control Document (ICD)-GPS-200 contact: ARINC Research Corporation, 2551 Riva
Road, Annapolis, MD 21401-7465. Their website is at http://www.arinc.com/.
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
IONB
Format
Field #
1
(header)
Message ID = 16
Message byte count = 76
Field Type
Sync
Checksum
Message ID
Message byte count
Bytes
3
1
4
4
Format
char
char
integer
integer
Units
bytes
Offset
0
3
4
8
2
3
4
Alpha constant term
Alpha 1st order term
Alpha 2nd order term
8
8
8
double
double
double
seconds
sec/semicircle
sec/(semic.)2
12
20
28
5
Alpha 3rd order term
8
double
36
6
7
8
Beta constant term
Beta 1st order term
Beta 2nd order term
8
8
8
double
double
double
sec/(semic.)3
seconds
sec/semic
sec/(semic.)2
44
52
60
9
Beta 3rd order term
8
double
sec/(semic.)3
68
Portable MEDLL Manual Rev 1
57
7 – NovAtel Format Data Logs
MPMA/B MULTIPATH METER
This log outputs information that estimates the amount of multipath the antenna is experiencing and how well MEDLL
has modelled the multipath signals.
It is recommended that this log be output only with the ‘onnew’ trigger option. There will be one log for every tracked
satellite per epoch. For example, if eleven satellites are being tracked, there will be eleven instances of this log every
epoch. MEDLL runs every second, so one epoch is equivalent to one second.
MPMA
$MPMA week
st
1 in phase
st
1 quad. phase
xx
[CR][LF]
Field #
1
2
3
4
5
6
7
8
9
10
22
23
45
46
47
seconds
…
…
Field Type
$MPMA
Week Number
Seconds of Week
PRN
Channel Tracking Status 12
MEDLL Status
Delay
Amplitude
Phase
1st in phase residual
…
12th in phase residual
1st Quadrature phase residual
…
12th Quadrature phase residual
*xx
[CR][LF]
prn chtrstat
th
12 in phase
12
th
medllstat
delay
amplitude
phase
quad. phase
Data Description
Log header
GPS week number
GPS seconds into the week
Satellite identifier
Channel tracking status bits, see Table 4 on 53
MEDLL status bits, see Table 8 on Page 59
Delay of multipath signal in chips
Amplitude of multipath signal
Phase of multipath signal in radians
In phase residual value from correlator 1
Repeated for each correlator
In phase residual value from correlator 12
Quadrature phase residual value from correlator 1
Repeated for each correlator
Quadrature phase residual value from correlator 12
Checksum
Sentence terminator
Example
$MPMA
0
27.77
29
6A84
103
1.08154941
0.01731431
- 0.00645047
0.00160142
…
- 0.00196318
- 0.00418267
…
- 0.00730140
*71
[CR][LF]
Example:
$MPMA,0,27.77,29,6A84,103,1.08154941,0.01731431,-0.00645047,0.00160142,
0.00164832,0.00078163,0.00001205,0.00083644,0.00240084,0.00214321,0.00079274,
-0.00032872,-0.00084985,0.00000891,-0.00196318,-0.00418267,-0.00443155,
-0.00665589,-0.00580890,-0.00078493,-0.00101275,0.00468876,0.00449791,
-0.00126932,-0.00140528,0.00004035,-0.00730140*71[CR][LF]
12
A description can be found on Page 53, Table 4
58
Portable MEDLL Manual Rev 1
7 – NovAtel Format Data Logs
MPMB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
9
10
22
23
45
Message ID = 95
Message byte count = 144
Data
Sync
Checksum
Message ID
Message Byte Count
Week Number
Seconds of Week
PRN
Channel Status
MEDLL Status
Delay
Amplitude
Phase
1st in phase residual
…
12th in phase residual
1st Quadrature phase residual
…
12th Quadrature phase residual
Bytes
3
1
4
4
4
8
4
4
4
4
4
4
4
Format
Char
Char
Integer
Integer
Integer
Double
Integer
Integer
Integer
Float
Float
Float
Float
Units
4
4
Float
Float
92
96
4
Float
140
bytes
weeks
seconds
C/A chips
Offset
0
3
4
8
12
16
24
28
32
36
40
44
48
The multipath amplitude and residuals are normalized with respect to the reference correlation function. D/U (desired
signal power relative to undesired signal power), in units of decibels (dB), can be calculated from the amplitude of the
multipath signal (-20 * log [amplitude of multipath signal]).
Table 8
Bit Position
0
1
2-6
7-9
10-31
Portable MEDLL Manual Rev 1
MEDLL Status Bits Table
Field Description
Sync bit: 1 if MEDLL channels in sync, 0 if not in sync.
Sync bit is set to 1 if the different hardware channels use
to track the same PRN are aligned.
Phase processing. When phase processing is on, the bit
is 1; MEDLL will determine the phase of the multipath
signal. If phase processing is set to 0, MEDLL will not
process the phase of the multipath signal. For Portable
MEDLL, the bit will always be 1 by default.
Type of MEDLL will always be 0 for Portable MEDLL.
Number of signals will always be 1 for Portable MEDLL.
Reserved. Set to 0.
59
7 - NovAtel Format Data Logs
POSA/B COMPUTED POSITION
This log will contain the last valid position and time calculated referenced to the antenna phase centre. The position is in
geographic coordinates in degrees based on your specified datum (default is WGS-84). The height is referenced to mean
sea level. The receiver time is in GPS weeks and seconds into the week. The estimated standard deviations of the solution
and current filter status are also included.
POSA
Structure:
$POSA week seconds lat lon hgt undulation
hgt std sol status *xx [CR][LF]
Field #
1
2
3
4
Field type
$POSA
week
seconds
lat
5
lon
6
7
hgt
undulation
8
9
10
11
12
13
14
datum ID
lat std
lon std
hgt std
sol status
*xx
[CR][LF]
datum ID
lat std
Data Description
Log header
GPS week number
GPS seconds into the week
Latitude of position in current datum, in degrees (DD.dddddddd).
A negative sign implies South latitude
Longitude of position in current datum, in degrees (DDD.dddddddd). A negative sign
implies West longitude
Height of position in current datum, in metres above mean sea level (MSL)
Geoidal separation, in metres, where positive is above spheroid and negative is
below spheroid
Current datum ID #, see Table 9, Page 61 and Table 10, Page 62.
Standard deviation of latitude solution element, in metres
Standard deviation of longitude solution element, in metres
Standard deviation of height solution element, in metres
Solution status as listed in Table 3, Page 53.
Checksum
Sentence terminator
lon std
Example
$POSA
637
511251.00
51.11161847
-114.03922149
1072.436
-16.198
61
26.636
6.758
78.459
0
*12
[CR][LF]
Example:
$POSA,637,511251.00,51.11161847,-114.03922149,1072.436,-16.198,61,26.636,
6.758,78.459,0*12[CR][LF]
60
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
POSB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
9
10
11
12
Message ID = 01
Message byte count = 88
Data
Sync
Checksum
Message ID
Message byte count
Bytes
3
1
4
4
Format
char
char
integer
integer
Week number
Seconds of week
Latitude
Longitude
Height
Undulation
Datum ID
StdDev of latitude
StdDev of longitude
StdDev of height
Solution status
4
8
8
8
8
8
4
8
8
8
4
integer
double
double
double
double
double
integer
double
double
double
integer
Units
Offset
0
3
4
8
bytes
weeks
seconds
degrees (+ is North, - is South)
degrees (+ is East, - is West)
metres with respect to MSL
metres
metres
metres
metres
12
16
24
32
40
48
56
60
68
76
84
The following tables contain the internal ellipsoid parameters and transformation parameters used in the GPSCard. The
values contained in these tables were derived from the following DMA technical reports:
1.
TR 8350.2
Department of Defence World Geodetic System 1984 – Its Definition and Relationships with
Local Geodetic Systems - Revised March 1, 1988.
2.
TR 8350.2B
Supplement to Department of Defence World Geodetic System 1984 Technical Report - Part
II - Parameters, Formulas, and Graphics for the Practical Application of WGS-84 - December
1, 1987.
Table 9
ELLIPSOID
Airy 1830
Modified Airy
Australian National
Bessel 1841
Clarke 1866
Clarke 1880
Everest (India 1830)
Everest (Brunei & E.Malaysia)
Everest (W.Malaysia & Singapore)
Geodetic Reference System 1980
Helmert 1906
Hough 1960
International 1924
South American 1969
World Geodetic System 1972
World Geodetic System 1984
Portable MEDLL Manual Rev 1
Reference Ellipsoid Constants
ID CODE
AW
AM
AN
BR
CC
CD
EA
EB
ED
RF
HE
HO
IN
SA
WD
WE
a (metres)
6377563.396
6377340.189
6378160.0
6377397.155
6378206.4
6378249.145
6377276.345
6377298.556
6377304.063
6378137.0
6378200.0
6378270.0
6378388.0
6378160.0
6378135.0
6378137.0
1/f
299.3249647
299.3249647
298.25
299.1528128
294.9786982
293.465
300.8017
300.8017
300.8017
298.257222101
298.30
297.00
297.00
298.25
298.26
298.257223563
f
0.00334085064038
0.00334085064038
0.00335289186924
0.00334277318217
0.00339007530409
0.00340756137870
0.00332444929666
0.00332444929666
0.00332444929666
0.00335281068118
0.00335232986926
0.00336700336700
0.00336700336700
0.00335289186924
0.00335277945417
0.00335281066475
61
7 - NovAtel Format Data Logs
Table 10
GPSCard
Datum ID
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
GPSCard
Datum ID
number
62
NAME
ADIND
ARC50
ARC60
AGD66
AGD84
BUKIT
ASTRO
CHATM
CARTH
CAPE
DJAKA
EGYPT
ED50
ED79
GUNSG
GEO49
GRB36
GUAM
HAWAII
KAUAI
MAUI
OAHU
HERAT
HJORS
HONGK
HUTZU
INDIA
IRE65
KERTA
KANDA
LIBER
LUZON
MINDA
MERCH
NAHR
NAD83
CANADA
ALASKA
NAD27
CARIBB
MEXICO
CAMER
MINNA
OMAN
PUERTO
NAME
Transformation Parameters (Local Geodetic to WGS-84)
DX
-162
-143
-160
-133
-134
-384
-104
175
-263
-136
-377
-130
-87
-86
-403
84
375
-100
89
45
65
56
-333
-73
-156
-634
289
506
-11
-97
-90
-133
-133
31
-231
0
-10
-5
-8
-7
-12
0
-92
-346
11
DX
DY
-12
-90
-8
-48
-48
664
-129
-38
6
-108
681
110
-98
-98
684
-22
-111
-248
-279
-290
-290
-284
-222
46
-271
-549
734
-122
851
787
40
-771
-70
146
-196
0
158
135
160
152
130
125
-93
-1
72
DY
DZ
206
-294
-300
148
149
-48
239
113
431
-292
-50
-13
-121
-119
41
209
431
259
-183
-172
-190
-181
114
-86
-189
-201
257
611
5
86
88
-51
-72
47
482
0
187
172
176
178
190
194
122
224
-101
DZ
DATUM DESCRIPTION
ELLIPSOID
Adindan (Ethiopia, Mali, Senegal & Sudan)
ARC 1950 (SW & SE Africa)
ARC 1960 (Kenya, Tanzania)
Australian Geodetic Datum 1966
Australian Geodetic Datum 1984
Bukit Rimpah (Indonesia)
Camp Area Astro (Antarctica)
Chatum 1971 (New Zealand)
Carthage (Tunisia)
CAPE (South Africa)
Djakarta (Indonesia)
Old Egyptian
European 1950
European 1979
G. Segara (Kalimantan - Indonesia)
Geodetic Datum 1949 (New Zealand)
Great Britain 1936 (Ordinance Survey)
Guam 1963 (Guam Island)
Hawaiian Hawaii (Old)
Hawaiian Kauai (Old)
Hawaiian Maui (Old)
Hawaiian Oahu (Old)
Herat North (Afghanistan)
Hjorsey 1955 (Iceland)
Hong Kong 1963
Hu-Tzu-Shan (Taiwan)
Indian (India, Nepal, Bangladesh)
Ireland 1965
Kertau 1948 (West Malaysia and Singapore)
Kandawala (Sri Lanka)
Liberia 1964
Luzon (Philippines excluding Mindanoa Is.)
Mindanoa Island
Merchich (Morocco)
Nahrwan (Saudi Arabia)
N. American 1983 (Includes Areas 37-42)
N. American Canada 1927
N. American Alaska 1927
N. American Conus 1927
N. American Caribbean
N. American Mexico
N. American Central America
Nigeria (Minna)
Oman
Puerto Rica and Virgin Islands
DATUM DESCRIPTION
Clarke 1880
Clarke 1880
Clarke 1880
Australian National
Australian National
Bessel 1841
International 1924
International 1924
Clarke 1880
Clarke 1880
Bessel 1841
Helmert 1906
International 1924
International 1924
Bessel 1841
International 1924
Airy 1830
Clarke 1866
International 1924
International 1924
International 1924
International 1924
International 1924
International 1924
International 1924
International 1924
Everest (EA)
Modified Airy
Everest (ED)
Everest (EA)
Clarke 1880
Clarke 1866
Clarke 1866
Clarke 1880
Clarke 1880
GRS-80
Clarke 1866
Clarke 1866
Clarke 1866
Clarke 1866
Clarke 1866
Clarke 1866
Clarke 1880
Clarke 1880
Clarke 1866
ELLIPSOID
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
QORNO
ROME
CHUA
SAM56
SAM69
CAMPO
SACOR
YACAR
TANAN
TIMBA
TOKYO
TRIST
VITI
WAK60
WGS72
WGS84
ZANDE
USER
164
-255
-134
-288
-57
-148
-206
-155
-189
-689
-128
-632
51
101
0
0
-265
0
138
-65
229
175
1
136
172
171
-242
691
481
438
391
52
0
0
120
0
-189
9
-29
-376
-41
90
-6
37
-91
-46
664
-609
-36
-39
4.5
0
-358
0
Qornoq (South Greenland)
Rome 1940 Sardinia Island
South American Chua Astro (Paraguay)
South American (Provisional 1956)
South American 1969
S. American Campo Inchauspe (Argentina)
South American Corrego Alegre (Brazil)
South American Yacare (Uruguay)
Tananarive Observatory 1925 (Madagascar)
Timbalai (Brunei and East Malaysia) 1948
Tokyo (Japan, Korea and Okinawa)
Tristan Astro 1968 (Tristan du Cunha)
Viti Levu 1916 (Fiji Islands)
Wake-Eniwetok (Marshall Islands)
World Geodetic System - 72
World Geodetic System - 84
Zanderidj (Surinam)
User Defined Datum Defaults
*
Default user datum is WGS 84.
*
The POSA/B log reports the Datum used according to the “GPSCard Datum ID” column.
Portable MEDLL Manual Rev 1
International 1924
International 1924
International 1924
International 1924
S. American 1969
International 1924
International 1924
International 1924
International 1924
Everest (EB)
Bessel 1841
International 1924
Clarke 1880
Hough 1960
WGS-72
WGS-84
International 1924
User *
63
7 - NovAtel Format Data Logs
RBTA/B SATELLITE BROADCAST DATA: RAW BITS
This message contains the satellite broadcast data in raw bits before Forward Error Correction (FEC) decoding or any
other processing. An individual message is sent for each PRN being tracked. For a given satellite, the message number
increments by one each time a new message is generated. This data matches the SBTA/B data if the message numbers are
equal. The data must be logged with the 'onnew' trigger activated to prevent loss of data.
RBTA
Structure:
$RBTA
week
raw bits
Field #
1
2
3
4
5
seconds
prn ch tr-status message #
# of bits
*xx [CR][LF]
Field type
$RBTA
week
seconds
prn
ch tr-status
6
7
message #
# of bits
8
raw bits
9
10
*xx
[CR][LF]
Data Description
Log header
GPS week number
GPS seconds into the week
PRN of satellite from which data originated
Channel Tracking Status (see Table 4, on Page
53)
Message sequence number
Number of bits transmitted in the message. At
present, always equals 256 bits.
256 bits compressed into a 32 bytes. Hence, 64
hex characters are output.
Checksum
Sentence terminator
Example
$RBTA
883
413908.000
115
80812F14
119300
256
30FB30FB30FB30F878DA62194000F18322931B
9EBDBC1CBC9324B68FBDAEBE8A
*42
[CR][LF]
Example:
$RBTA,883,413908.000,115,80812F14,119300,256,30FB30FB30FB30F878DA62194000F1832293
1B9EBDBC1CBC9324B68FBDAEBE8A*42[CR][LF]
RBTB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
64
Message ID = 52
Data
Sync
Checksum
Message ID
Message byte count
Week number
Seconds of week
PRN number
Channel Tracking Status
Message #
# of Bits
Raw Bits
Message byte count = 72
Bytes
3
1
4
4
Format
char
char
integer
integer
Units
Offset
bytes
0
3
4
8
4
8
4
4
4
4
32
integer
double
integer
integer
integer
integer
char
weeks
seconds
1-999
n/a
n/a
n/a
n/a
12
16
24
28
32
36
40
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
RCCA RECEIVER CONFIGURATION
This log outputs a list of the current receiver command settings. Observing this log is a good way to monitor the
receiver’s configuration settings. If these messages are logged directly after powering up the receiver, they will contain
the default configuration settings.
NOTE1: In addition to typical log data as described in this manual, there may be additional messages output by the
receiver (see Appendix C on Page 88, for more on information messages).
NOTE2: Each line is followed by a carriage return ([CR][LF]).
RCCA
Example default:
$RCCA,COM1,9600,N,8,1,N,OFF,ON*2B
$RCCA,COM1_DTR,HIGH*70
$RCCA,COM1_RTS,HIGH*67
$RCCA,ACCEPT,COM1,COMMANDS*5B
$RCCA,COM2,9600,N,8,1,N,OFF,ON*28
$RCCA,COM2_DTR,HIGH*73
$RCCA,COM2_RTS,HIGH*64
$RCCA,ACCEPT,COM2,COMMANDS*58
$RCCA,UNDULATION,TABLE*56
$RCCA,DATUM,WGS84*15
$RCCA,USERDATUM,6378137.000,298.257223563,0.000,0.000,0.000,0.000,0.000,0.000,0.0
00*6A
$RCCA,SETNAV,DISABLE*5C
$RCCA,MAGVAR,0.000*33
$RCCA,DYNAMICS,AIR*4F
$RCCA,UNASSIGNALL*64
$RCCA,UNLOCKOUTALL*20
$RCCA,RESETHEALTHALL*37
$RCCA,UNFIX*73
$RCCA,SETDGPSID,ALL*1D
$RCCA,RTCMRULE,6CR*32
$RCCA,RTCM16T,*48
$RCCA,CSMOOTH,20.00,20.00*7E
$RCCA,ECUTOFF,5.00*40
$RCCA,FREQUENCY_OUT,DISABLE*12
$RCCA,EXTERNALCLOCK,OCXO*5D
$RCCA,CLOCKADJUST,ENABLE*47
$RCCA,SETTIMESYNC,DISABLE*17
$RCCA,SETL1OFFSET,0.000000*3F
$RCCA,MESSAGES,COM1,ON*56
$RCCA,MESSAGES,COM2,OFF*1B
$RCCA,MESSAGES,CONSOLE,ON*71
$RCCA,DGPSTIMEOUT,60.00,120.00*51
$RCCA,POSAVE,DISABLE*59
$RCCA,CONFIG,G10W2*3A
$RCCA,DIFF_PROTOCOL,DISABLED*47
$RCCA,UNLOGALL*21
Portable MEDLL Manual Rev 1
65
7 - NovAtel Format Data Logs
REPA/B RAW EPHEMERIS
This log contains the raw binary information for sub-frames one, two and three from the satellite with the parity
information removed. Each sub-frame is 240 bits long (10 words – 24 bits each) and the log contains a total 720 bits (90
bytes) of information (240 bits x 3 sub-frames). This information is preceded by the PRN number of the satellite from
which it originated. This message will not be generated unless all 10 words from all 3 frames have passed parity.
An individual message is sent for each PRN being tracked. For a given satellite, the message number increments by one
each time a new message is generated.
Ephemeris data whose time of ephemeris is older than six hours will not be shown.
REPA
Structure:
$REPA
Field #
1
2
3
prn
subframe1 Subframe2 subframe3 *xx [CR][LF]
Field type
$REPA
prn
subframe1
Data Description
Log header
PRN of satellite from which data originated
Sub-frame 1 of ephemeris data (60 hex characters)
4
subframe2
Sub-frame 2 of ephemeris data (60 hex characters)
5
subframe3
Sub-frame 3 of ephemeris data (60 hex characters)
6
7
*xx
[CR][LF]
Checksum
Sentence terminator
Example
$REPA
14
8B09DC17B9079DD7007D5DE404A9B2D
04CF671C6036612560000021804FD
8B09DC17B98A66FF713092F12B359D
FF7A0254088E1656A10BE2FF125655
8B09DC17B78F0027192056EAFFDF2724C
9FE159675A8B468FFA8D066F743
*57
[CR][LF]
Example:
$REPA,14,8B09DC17B9079DD7007D5DE404A9B2D04CF671C6036612560000021804FD,
8B09DC17B98A66FF713092F12B359DFF7A0254088E1656A10BE2FF125655,
8B09DC17B78F0027192056EAFFDF2724C9FE159675A8B468FFA8D066F743*57[CR][LF]
REPB
Format:
Field #
1
(header)
2
3-4-5
6
66
Message ID = 14
Message byte count = 108
Data
Sync
Checksum
Message ID
Message byte count
Bytes
3
1
4
4
Format
char
char
integer
integer
PRN number
Ephemeris data
Filler bytes
Reserved. Set to 0.
4
90
2
integer
char
char
Units
bytes
1-32
data [90]
Offset
0
3
4
8
12
16
106
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
RGEA/B/D
CHANNEL RANGE MEASUREMENTS
RGEA/B contains the channel range measurements for the currently observed satellites i.e. those that are in tracking
statee4. These logs contain all of the extended tracking status bits. The RGED message is a compressed form of the
RGEB message.
It is important to ensure that the receiver clock has been set and can be monitored by the bits in the rec-status field. Large
jumps in range as well as Accumulated Doppler Range (ADR) will occur as the clock is being adjusted. If the ADR
measurement is being used in precise phase processing, it is important not to use the ADR if the "parity known" flag in
the tr-status field is not set as there may exist a half (1/2) cycle ambiguity on the measurement. The tracking error
estimate of the pseudorange and carrier phase (ADR) is the thermal noise of the receiver tracking loops only. It does not
account for possible multipath errors or atmospheric delays.
As shown in Table 4 for the Channel Tracking Status word, bit 19 shows the observation is for L1. This is to aid in
parsing the data.
RGEA
Structure:
$RGEA week
seconds # obs rec-status
prn psr psr std
adr adr std dopp S/No
:
prn psr psr std
adr adr std dopp S/No
*xx [CR][LF]
Field #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Field type
$RGEA
week
seconds
# obs
rec-status
prn
psr
psr std
adr
adr std
dopp
C/N0
locktime
ch tr-status
15-23
...
variable
variable
*xx
[CR][LF]
Portable MEDLL Manual Rev 1
locktime
ch tr-status
locktime
ch tr-status
Data Description
Log header
GPS week number
GPS seconds into the week (receiver time, not corrected for clock error)
Number of satellite observations with information to follow
Receiver self-test status (see Table 11 on Page 69)
Satellite PRN number (1-32) of range measurement
Pseudorange measurement (m)
Pseudorange measurement standard deviation (m)
Carrier phase, in cycles (accumulated Doppler range)
Estimated carrier phase standard deviation (cycles)
Instantaneous carrier Doppler frequency (Hz)
Signal to noise density ratio C/N0 = 10[log10(S/N0)] (dB-Hz)
Number of seconds of continuous tracking (no cycle slipping)
Channel tracking status: hexadecimal number indicating phase lock, channel
number and channel state as shown in Table 4, Page 53
Next observation
Next observation
Checksum
Sentence terminator
Example
$RGEA
845
511089.00
14
000B20FF
4
23907330.296
0.119
-125633783.992
0.010
3714.037
44.8
1928.850
82E04
*30
[CR][LF]
67
7 - NovAtel Format Data Logs
Example (carriage returns have been added between observations for clarity):
$RGEA,845,511089.00,14,000B20FF
4,23907330.296,0.119,-125633783.992,0.010,3714.037,44.8,1928.850,82E04,
4,23907329.623,1.648,-97896180.284,0.013,2894.285,35.0,1746.760,582E0B,
2,21298444.942,0.040,-111954153.747,0.006,-1734.838,54.2,17466.670,82E14,
2,21298444.466,0.637,-87236867.557,0.006,-1351.607,43.3,17557.260,582E1B,
9,22048754.383,0.063,-115874135.450,0.006,2174.006,50.4,5489.100,82E24,
9,22048754.424,0.641,-90291443.071,0.006,1694.238,43.2,5489.100,582E2B,
15,23191384.847,0.261,-121887295.980,0.017,-2069.744,38.0,9924.740,82E34,
15,23191384.663,0.596,-94977002.452,0.010,-1612.587,43.8,9881.830,582E3B,
26,24063897.737,0.199,-126477739.189,0.014,-2654.682,40.3,12821.640,82E54,
26,24063898.913,1.043,-98553986.239,0.013,-2068.380,39.0,12793.280,582E5B,
7,20213352.139,0.037,-106237901.461,0.005,439.943,55.0,10313.040,82E74,
7,20213351.196,0.498,-82782498.454,0.007,343.020,45.4,9977.400,582E7B,
27,24393726.829,0.123,-128229016.323,0.012,-4047.338,44.5,22354.119,82E94,
27,24393728.057,1.805,-99918535.513,0.013,-3153.559,34.2,22301.830,582E9B
*30[CR][LF]
RGEB
Format:
Field #
Message byte count = 32 + (obs x 44)
Bytes
Format
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
2
3
4
5
Week number
Seconds of week
Number of observations (obs)
Receiver self-test status (see Table 11)
4
8
4
4
integer
double
integer
integer
6
7
8
9
10
11
12
PRN
Pseudorange
StdDev pseudorange
Carrier phase – accumulated Doppler range
StdDev – accumulated Doppler range
Doppler frequency
C/N0
4
8
4
8
4
4
4
integer
double
float
double
float
float
float
13
14
Locktime
Channel Tracking status
4
4
float
integer
1
(header)
15...
68
Message ID = 32
Data
Units
bytes
weeks
s
m
m
cycles
cycles
Hz
dB-Hz
s
Offset
0
3
4
8
12
16
24
28
32
36
44
48
56
60
64
68
72
Next PRN offset = 32 + (obs# x 44) where obs# = 0 to obs
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
RGED
Format:
Message ID = 65
Field #
Message byte count = 24 + (obs x 20)
Data
Bytes
Format
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
2
3
4
5
Number of observations (obs)
Week number
Seconds of week
Receiver self test status (see Table
11)
2
2
4
4
integer
integer
integer
integer
weeks
s
12
14
16
20
6
First PRN range record
20
integer
Only bits 0 – 23 are represented
24
1
(header)
Units
Offset
0
3
4
8
bytes
Next PRN offset = 24 + (20 x obs#) where obs# = 0 to obs
Table 11
N7
N 6
27
26
25
N 5
24
23
22
21
N 4
20
19
18
17
N 3
16
15
14
13
N 2
12
11
10
9
Receiver Self-Test Status Codes
N 1
8
7
6
5
N 0
4
3
2
1
0
<- <- Nibble Number
Bit
Descriptio n
Range Values
Hex Value
lsb = 0 ANTENNA
1=good, 0 =bad
00000001
1 L1PLL
1=good, 0 =bad
00000002
2 RAM
1=good, 0 =bad
00000004
3 SOFTWARE INTEGRITY
1=good, 0 =bad
00000008
4 MINOS
1=good, 0 =bad
00000010
5 L1AGC
1=good, 0 =bad
00000020
6 COM 1
1=good, 0 =bad
00000040
7 COM 2
1=good, 0 =bad
00000080
8 WEEK
1=not set , 0 =set
00000100
9 COARSETIME
1=not set , 0 =set
00000200
10 FINETIME
1=not set , 0 =set
00000400
11 L1JAMMER
1=pr esent , 0 =normal
00000800
12 BUFFER COM 1
1=over r un, 0 =nor mal
00001000
13 BUFFER COM 2
1=over r un, 0 =nor mal
00002000
14 BUFFER CONSOLE
1=over r un, 0 =nor mal
00004000
15 RANGE BUFFER OVERLOAD
1=over load, 0 =normal
00008000
16 Reserved
17
18
19
20
21
22
23
24
25
26
27
28- 31
GPSCard examples:
MEDLL:
All OK = 0000 0000 0000 0000 0000 0000 1111 1111 (binary) = 000000FF (hexadecimal)
Notes:
1. Bit 3: Refers to the periodic code check.
2. Bits 2, 4, 6, 7: these are set only once when the GPSCard is first powered up. All other bits are set by internal test processes periodically.
3. Bits 12-15: Flag is reset to 0 five minutes after the last overrun/overload condition has occurred.
4. Bits 17-20: These bits are always set to 0 for MEDLL
Portable MEDLL Manual Rev 1
69
7 - NovAtel Format Data Logs
Receiver Status – Detailed Bit Descriptions of Self-Test Word
What follows is a detailed description of each bit setting in the Receiver Self-Test Status word (see Table 11 on Page
69). Additional information is also included in Table 13, on Page 72.
The following information is output in the receiver status bits:
Table 12
Bit #
0
Range Value
1 = good
0 = bad
1 = good
0 = bad
1 = good
0 = bad
Name
Antenna
3
1 = good
0 = bad
Software
Integrity
4
1 = good
0 = bad
DSP
5
1 = good
0 = bad
L1 AGC
6
1 = good
0 = bad
COM1
7
1 = good
0 = bad
1 = not set
0 = set
COM2
1 = not set
0 = set
Coarse Time
1
2
8
9
70
L1 PLL
RAM
WEEK
Receiver Self-Test Status Bits
Description
This is only verified if the receiver is supplying power to the antenna. For all EGNOS receiver
models, the antenna will not be powered so this bit is not used.
Verifies that the L1 VCO is locked and sets the bit to good if the test passes.
RAM is tested by the assumption that if the code is running and we get to set the RAM good bit,
then the RAM itself must be good. The bit is never set to bad in the software. If the RAM is
determined to be bad during the boot sequence, the software is not run and the LED on the front
panel will be flashed at 4Hz. No additional error message is output when this test fails.
This bit will indicate that the authorization code has successfully been used to check the integrity
of the software loaded on the card. On success, the bit is set to good. On failure, the receiver will
be reset in an attempt to alleviate the problem after outputting a fatal !ERRA message of type 1,
see Page 88. If the problem persists, attempt to reload the card. In the event that reloading the
receiver does not fix the problem, the unit will need to be replaced.
This function performs a readback of the MINOS Master Control Register using alternating test
patterns for both master and slave MINOS on the board and sets the bit to good if the test
passes. A failure indicates that there is a problem with the MINOS and the unit should be
replaced. No additional error message is output when this test fails.
Verifies that the L1 AGC is currently not being adjusted and is properly calibrated and sets the bit
to good if the test passes. This is only done on the MEDLL Master and OEM3 cards, as there is
no AGC on the MEDLL Slave cards.
Failure of this test could be the result of various possibilities such as: bad antenna LNA,
excessive loss in the antenna cable, faulty RF down-converter, or a pulsating or high power
jamming signal causing interference. If this bit is continuously set to clear, you cannot identify an
external cause for the failed test.
The DUART is tested using an internal loopback verifying the transmit and receive shift registers,
DTR/DSR, RTS/CTS, and RI/DCD lines and sets the bit to good if the test passes. If the test fails,
there will most likely be no output from the receiver since the COM port has failed. In the event
that the COM port has failed but there are still logs being output, there may be additional
problems with the ASIC (since the DUART is integrated into the MINOS) and the unit should be
replaced.
This test is identical to the COM1 test.
The week is initialised to not set at start-up. Once the week has been determined (by the
decoding of navigation data) the bit is set to 0. Once the week has been determined, it will remain
set until a receiver reset occurs.
If this bit is not set to zero, then the observation data, pseudorange, carrier phase, and Doppler
measurements may jump as the clock adjusts itself.
The coarse time is initialised to not set at start-up. Once the coarse time has been determined (by
decoding navigation data) the bit is set to 0. Once coarse time has been determined, it will remain
set until a receiver reset occurs.
If this bit is not set to zero, then the observation data, pseudorange, carrier phase, and Doppler
measurements may jump as the clock adjusts itself.
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
Bit #
10
Range Value
1 = not set
0 = set
Name
Fine Time
11
1 = present
0 = normal
L1 Jammer
12
1 = overrun
0 = normal
Buffer COM1
13
1 = overrun
0 = normal
Buffer COM2
14
1 = overrun
0 = normal
Buffer Console
15
1 = overrun
0 = normal
Range Buffer
Overrun 13
16-31
Reserved
13
Description
The fine time is initialised to not set at start-up. Once the fine time has been determined (by
calculating a position/time solution) the bit is set to 0. Since CLOCKADJUST is disabled, once
the fine time has been determined it will remain set until a receiver reset occurs.
If this bit is not set to zero, then the observation data, pseudorange, carrier phase, and Doppler
measurements may jump as the clock adjusts itself.
This test checks to see if the L1 AGC has detected a jammer and sets the bit to indicate its
presence. You should monitor this bit, and if set to 1, do your best to remedy the cause of the
jamming signal. Nearby transmitters or other electronic equipment could be the cause of
interference; you may find it necessary to relocate your antenna position if the problem persists.
The COM1 UART Tx and Rx status lines are checked and if either has experienced an overrun,
this status bit is set. If set, it will remain in that state for 2 seconds beyond the last overrun. Overrun is caused by requesting more log data than can be taken from the RIMS-C receiver because
of baud rate limitations or slow communications equipment. If this happens, the new data
attempting to be loaded into the buffer will be discarded. The receiver will not load a partial data
record into an output buffer. The flag resets to zero, 2 seconds after the last overrun occurred.
The COM2 UART Tx and Rx status lines are checked and if either has experienced an overrun,
this status bit is set. If set, it will remain in that state for 2 seconds beyond the last overrun. Overrun is caused by requesting more log data than can be taken from the RIMS-C receiver because
of baud rate limitations or slow communications equipment. If this happens, the new data
attempting to be loaded into the buffer will be discarded. The receiver will not load a partial data
record into an output buffer. The flag resets to zero, 2 seconds after the last overrun occurred.
The console Tx and Rx status lines are checked and if either has experienced an overrun, this
status bit is set. If set, it will remain in that state for 2 seconds beyond the last overrun. Over-run
is caused by requesting more log data than can be taken from the RIMS-C receiver because of
baud rate limitations or slow communications equipment. If this happens, the new data attempting
to be loaded into the buffer will be discarded. The receiver will not load a partial data record into
an output buffer. The flag resets to zero, 2 seconds after the last overrun occurred.
Verifies that there is space in a circular RAM buffer for range measurements and sets the bit to
good if the test passes. When the buffer is overloaded (there are too many successive range
measurements for the CPU to service) the bit is set to overrun. The bit will remain set for 2
seconds after the last overrun and then the bit will be cleared.
Requesting an excessive amount of information from the receiver may cause this. If this condition
is occurring, limit redundant data logging or reconfigure the receiver to output binary data output
formats, or both. You should attempt to tune the logging requirements to keep the idle time above
20% for best operation. If the average idle CPU drops below 10% for prolonged periods of time
(2-5 seconds), critical errors may result in internal data loss and the over-load bit will be set to 1.
You can monitor the range buffer CPU idle time by using the RVSA log message. The flag is
reset 2 seconds after the last overload occurred.
As the amount of buffer space becomes limited, the software will begin to slow down the position calculation rate. If
the buffer becomes further limited, the software will begin to skip range measurement processing. Priority processing
goes to the tracking loops.
Portable MEDLL Manual Rev 1
71
7 - NovAtel Format Data Logs
Table 13
Additional Information About Portable MEDLL Receiver Self-Test Status Word
The bits have been place into 4 categories. They are:
1.
2.
Not Used in Portable MEDLL Rx: The user can ignore this bit.
Diagnostics: This bit does not need to be continually monitored by the user but can provide useful information if a problem
is detected.
3. Checked at Start-up: This test is done at power-up of the receiver. This should show ‘valid’ status before continuing.
4. Continuous Monitoring: This bit should be continually monitored by the user. It either indicates a problem or a change of
status.
Bit
Description
0
ANTENNA
1
2
L1 PLL
RAM
3
4
5
SOFTWARE INTEGRITY
MINOS
L1 AGC
6
7
8
9
10
11
12
13
14
15
16-31
COM 1
COM 2
WEEK
COARSETIME
FINETIME
L1 JAMMER
BUFFER COM1
BUFFER COM2
BUFFER CONSOLE
BUFFER OVERLOAD
Reserved
72
Category
Comments
Not Used In Portable MEDLL No antenna power provided by the receiver.
Rx
Diagnostics
Can be used for diagnostics if a problem is detected.
Checked at Start-up
Always 1 on start-up. A 0 will remain unseen; the computer is not
working.
Continuous Monitoring
ROM CRC failure.
Checked at Start-up
Diagnostics
Indicates the AGC has been adjusted. If there is a problem it will show up
in the C/No and ranges residuals.
Checked at Start-up
Checked at Start-up
Continuous Monitoring
Continuous Monitoring
Continuous Monitoring
Continuous Monitoring
Indicates there may be a jammer present on L1.
Continuous Monitoring
Continuous Monitoring
Continuous Monitoring
Continuous Monitoring
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
Table 14
Data
PRN 14 15
C/N0 16
Lock time 17
ADR 18
Doppler Frequency
Pseudorange
StdDev – ADR
StdDev – pseudorange
Channel tracking status 20
14
15
16
17
18
Range Record Format (RGED Only)
Bits from first to last
0..5
6..10
11..31
32..63
68..95
64..67msn; 96..127 lsw
128..131
132..135
136..159
Length (bits)
6
5
21
32
28
36
4
4
24
Format
integer
integer
integer
integer 2’s compliment
integer 2’s compliment
integer 2’s compliment
integer
integer
Scale Factor
1
(20 + n) dB-Hz
1/32 s
1/256 cycles
1/256 Hz
1/128 m
(n + 1) / 512 cycles
(see footnote) 19
see Table 4, Page 53
Only PRNs 1-63 are reported correctly. (Note: while there are only 32 PRNs in the basic GPS scheme, situations exist which require the use
of additional PRNs.)
The PRN offsets for WAAS have been mapped to the same range as GPS, i.e. 1-19, while the PRN offsets for GLONASS are 1-29.
C/N0 is constrained to a value between 20 – 51 dB-Hz. Thus, if it is reported that C/N0 = 20 dB-Hz, the actual value could be less.
Likewise, if it is reported that C/N0 = 51 dB-Hz, the true value could be greater.
Lock time rolls over after 2,097,151 seconds.
ADR (Accumulated Doppler Range) is calculated as follows:
ADR_ROLLS = (-RGED_PSR / WAVELENGTH – RGED_ADR)/MAX_VALUE
Round to the closest integer
IF (ADR_ROLLS < -0.5 )
ADR_ROLLS = ADR_ROLSS –0.5
ELSE
ADR_ROLLS = ADR_ROLLS + 0.5
At this point integerise ADR_ROLLS
CORRECTED_ADR = RGED_ADR – (MAX_VALUE * ADR_ROLLS)
where:
ADR has units of cycles
WAVELENGTH = 0.1902936727984 for L1
MAX_VALUE = 8388608
19
20
Code
0
1
2
3
4
5
6
7
8
9
10
11
12
13
RGED
0.00 to 0.050
0.051 to 0.075
0.076 to 0.113
0.114 to 0.169
0.170 to 0.253
0.254 to 0.380
0.381 to 0.570
0.571 to 0.854
0.855 to 1.281
1.282 to 2.375
2.376 to 4.750
4.751 to 9.500
9.501 to 19.000
19.001 to 38.000
14
15
38.001 to 76.000
76.001 to 152.000
Only bits 0-23 are represented in the RGED log.
Portable MEDLL Manual Rev 1
73
7 - NovAtel Format Data Logs
RVSA/B RECEIVER STATUS
This log conveys various status parameters of the receiver. If the receiver is a multiple-GPSCard unit with a master card
(e.g. MEDLL), certain parameters are repeated for each individual GPSCard. If the receiver is composed of only one
GPSCard, then only the parameters for that unit are listed.
Note that the number of satellite channels represents the maximum number of channels reporting information in logs such
as ETSA/B and RGEA/B/D.
RVSA
Structure:
$RVSA week seconds
idle status
:
idle status
*xx [CR][LF]
Field #
1
2
3
4
5
6
7
sat_chan
sig_chan
num reserved
Field type
$RVSA
week
seconds
sat_chan
sig_chan
num
Reserved
Data Description
Log header
GPS week number
GPS seconds into the week.
Number of satellite channels
Number of signal channels
Number of cards
Reserved. Set to 0.
8
idle
9
status
First GPSCard: CPU idle time. Averaged over a 1 second
period (percent).
First GPSCard: Self-test status (see Table 11 on Page 69)
10…
...
variable
variable
Example
$RVSA
847
318923.00
12
24
1
22
000B00FF
Next GPSCard: CPU idle time & self-test status
Next GPSCard: CPU idle time & self-test status
*xx
[CR][LF]
Checksum
Sentence terminator
*42
[CR][LF]
MEDLL Example:
$RVSA,77,162465.00,16,16,8,0,53.00,42000FF,66.00,42000FF,68.00,42000FF,77.00,42000FF,69.00,42000FF,87.00,4
2000FF,89.00,42000FF,88.00,42000FF*0B
74
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
RVSB
Format:
Message ID = 56
Field #
Data
Message byte count = 28 + (8 x number of cards )
Bytes
Format
Units
Offset
1
(header)
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
2
3
4
4
8
1
integer
double
char
1
char
25
6
7
Week number
Seconds of week
Number of satellite
channels
Number of signal
channels
Number of cards
Reserved. Set to 0.
1
1
char
byte
26
27
8
9
CPU idle time
Self-test status
4
4
float
integer
5
8 & 9 are repeated for
each card
bytes
weeks
s
percent
0
3
4
8
12
16
24
28
32
Next Card offset = 28 + ( 8 x card# ) where card# = 0 – (number of cards – 1)
Portable MEDLL Manual Rev 1
75
7 - NovAtel Format Data Logs
SATA/B SATELLITE SPECIFIC DATA
This log provides satellite specific data for satellites actually being tracked. The record length is variable and depends on
the number of satellites.
Each satellite being tracked has a reject code indicating whether it is used in the solution, or the reason for its rejection
from the solution. The reject value of 0 indicates the observation is being used in the position solution. Values of 1
through 13 indicate the observation has been rejected for the reasons specified in Table 7 on Page 54.
SATA
Structure:
$SATA week Seconds sol status # obs
prn azimuth elevation residual reject code
:
prn azimuth elevation residual reject code
Field #
1
2
3
4
*xx [CR][LF]
Field type
$SATA
week
seconds
sol status
Data Description
Log header
GPS week number
GPS seconds into the week
Solution status as listed in Table 3, Page 53
5
# obs
Number of satellite observations with information to follow
6
7
8
9
prn
azimuth
elevation
residual
Satellite PRN number (1-32)
Satellite azimuth from user position with respect to True North, in degrees
Satellite elevation from user position with respect to the horizon, in degrees
Satellite range residual from position solution for each satellite, in metres
10
reject code
Indicates that the range is being used in the solution (code 0) or that it was rejected (code 113), as shown in Table 7 on Page 54
..
Next PRN
*xx
[CR][LF]
Checksum
Sentence terminator
11...
variable
variable
Example
$SATA
637
513902.00
0
7
18
168.92
5.52
9.582
0
*1F
[CR][LF]
Example:
$SATA,637,513902.00,0,7,18,168.92,5.52,9.582,0,6,308.12,55.48,0.737,0,
15,110.36,5.87,16.010,0,11,49.63,40.29,-0.391,0,
2,250.05,58.89,-12.153,0,16,258.55,8.19,-20.237,0,
19,118.10,49.46,-14.803,0*1F[CR][LF]
76
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
SATB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
9
10
11...
Message ID = 12
Data
Sync
Checksum
Message ID
Message byte count
Week number
Seconds of week
Solution status
Number of observations (obs)
Message byte count = 32 + (obs*32)
Bytes
3
1
4
4
Format
char
char
integer
integer
4
8
4
4
integer
double
integer
integer
PRN
4
integer
Azimuth
8
double
Elevation
8
double
Residual
8
double
Reject code
4
integer
Next PRN offset = 32 + (obs# * 32) where obs# varies from 0 to (obs-1)
Portable MEDLL Manual Rev 1
Units
bytes
weeks
seconds
degrees
degrees
metres
Offset
0
3
4
8
12
16
24
28
32
36
44
52
60
77
7 - NovAtel Format Data Logs
SBTA/B SATELLITE BROADCAST DATA: RAW SYMBOLS
This message contains the satellite broadcast data in raw symbols before FEC decoding or any other processing. An
individual message is sent for each PRN being tracked. For a given satellite, the message number increments by one each
time a new message is generated. This data matches the RBTA/B data if the message numbers are equal. The data must
be logged with the 'onnew' trigger activated to prevent loss of data.
SBTA
Structure:
$SBTA
week
raw symbols
seconds
*xx
Field #
1
2
3
4
5
6
7
Field type
$SBTA
week
seconds
prn
cstatus
message #
# of symbols
8
raw symbols
9
10
*xx
[CR][LF]
prn cstatus
message # # of symbols
[CR][LF]
Data Description
Log header
GPS week number
GPS seconds into the week
PRN of satellite from which data originated
Channel Tracking Status
Message sequence number
Number of symbols transmitted in the message. At
present, always equals 256 bits.
256 symbols compressed into a 128 bytes, i.e. 4
bits/symbol. Hence, 256 hex characters are output.
If FEC decoding is enabled, soft symbols are
output with values ranging from -3 to 3. Otherwise
1's and 0's are output.
Checksum
Sentence terminator
Example
$SBTA
883
413908.000
120
80812F14
119300
256
EE33EEEE33333E33EE33EEEE33333E33EE33EEEE3333
3E33EE33EEEE33333EEEE3333EEE33E33E3EE33EEE3E
EEE33EE3E3EEEEEEEEEEEEEE3333EEE33EEEEE33EE
3EEE3E3EE3EE33EEE33E333EE3333E3E3333E33E3333
EEEEE333EE3E3333EE3EE3EE33EE3EE3EE3E33E33E3
EEE33333E3333E33E3E333E3E33333E3EEE3E3E
*4C
[CR][LF]
Example:
$SBTA,883,413908.000,120,80812F14,119300,256,EE33EEEE33333E33EE33EEEE333
33E33EE33EEEE33333E33EE33EEEE33333EEEE3333EEE33E33E3EE33EEE3EEEE33EE3E3E
EEEEEEEEEEEEE3333EEE33EEEEE33EE3EEE3E3EE3EE33EEE33E333EE3333E3E3333E33E3
333EEEEE333EE3E3333EE3EE3EE33EE3EE3EE3E33E33E3EEE33333E3333E33E3E333E3E3
3333E3EEE3E3E*4C[CR][LF]
SBTB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
78
Message ID = 53
Data
Sync
Checksum
Message ID
Message byte count
Week number
Seconds of week
PRN number
Channel Status
Message #
# of Symbols
Raw Symbols
Message byte count = 168
Bytes
3
1
4
4
Format
char
char
integer
integer
4
8
4
4
4
4
128
integer
double
integer
integer
integer
integer
char
Units
bytes
weeks
seconds
1-999
n/a
n/a
n/a
n/a
Offset
0
3
4
8
12
16
24
28
32
36
40
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
TM1A/B TIME OF 1PPS
This log provides the time of the GPSCard 1PPS in GPS week number and seconds into the week. It also includes the
receiver clock offset, the standard deviation of the receiver clock offset and clock model status. This log will output at a
maximum rate of 1 Hz.
TM1A
Structure:
$TM1A
week
Field #
1
2
3
Field type
$TM1A
week
seconds
4
offset
5
6
offset std
utc offset
7
cm status
8
9
*xx
[CR][LF]
seconds
offset offset std
utc offset cm status *xx
Data Description
Log header
GPS week number
GPS seconds into the week at the epoch coincident with the 1PPS output strobe (receiver
time)
Receiver clock offset, in seconds. A positive offset implies that the receiver clock is ahead
of GPS Time. To derive GPS time, use the following formula:
GPS time = receiver time – (offset)
Standard deviation of receiver clock offset, in seconds
This field represents the offset of GPS time from UTC time, computed using almanac
parameters. To reconstruct UTC time, algebraically subtract this correction from field 3
above (GPS seconds):
UTC time = GPS time – (utc offset)
Receiver Clock Model Status where 0 is valid and values from -20 to -1 imply that the
model is in the process of stabilization
Checksum
Sentence terminator
[CR][LF]
Example
$TM1A
794
414634.999999966
-0.000000078
0.000000021
-9.999999998
0
*57
[CR][LF]
Example:
$TM1A,794,414634.999999966,-0.000000078,0.000000021,-9.999999998,0*57[CR][LF]
TM1B
Format:
Field #
1
(header)
2
3
4
5
6
7
Message ID = 03
Message byte count = 52
Data
Sync
Checksum
Message ID
Message byte count
Bytes
3
1
4
4
Format
char
char
integer
integer
Week number
Seconds of week
Clock offset
StdDev clock offset
UTC offset
Clock model status
4
8
8
8
8
4
integer
double
double
double
double
integer
Portable MEDLL Manual Rev 1
Units
bytes
weeks
seconds
seconds
seconds
seconds
0 = good, -1 to -20 = bad
Offset
0
3
4
8
12
16
24
32
40
48
79
7 - NovAtel Format Data Logs
UTCA/B DECODED ALMANAC - UTC TIME PARAMETERS
The UTC time parameters (UTCA/B) are provided following the last almanac records when an ALMA/B message has
been logged. The UTCA/B message cannot be logged individually or independently of the ALMA/B message.
For more information on Almanac data, refer to the GPS SPS Signal Specification.
UTCA
Structure:
$UTCA pct p1ot
*xx [CR][LF]
Field #
1
2
3
4
5
6
7
8
9
10
11
data-ref
Field type
$UTCA
pct
p1ot
data-ref
wk #-utc
wk #-lset
delta-time
lsop
day #-lset
*xx
[CR][LF]
wk#-utc
wk#-lset
delta-time
Data Description
Log header
Polynomial constant term, seconds
Polynomial 1st order term, seconds/second
UTC data reference time, seconds
Week number of UTC reference, weeks
Week number for leap sec effect time, weeks
Delta time due to leap sec, seconds
For use when leap sec on past, seconds
Day number for leap sec effect time, days
Checksum
Sentence terminator
lsop
day #-lset
Example
$UTCA
-2.235174179077148E-008
-1.243449787580175E-014
32768
745
755
9
10
5
*37
[CR][LF]
Example:
$UTCA,-2.235174179077148E-008,-1.243449787580175E-014,32768,745,755,9,10,5*37
[CR][LF]
UTCB
Format:
Field #
1
(header)
2
3
4
5
6
7
8
9
80
Message ID = 17
Message byte count = 52
Field Type
Sync
Checksum
Message ID
Message byte count
Polynomial constant term
Polynomial 1st order term
UTC data reference time
Week number UTC reference
Week number for leap sec effect time
Delta time due to leap sec
For use when leap sec on past
Day number for leap sec effect time
Bytes
3
1
4
4
Format
char
char
integer
integer
8
8
4
4
4
4
4
4
double
double
integer
integer
integer
integer
integer
integer
Units
Offset
0
3
4
8
seconds
seconds/second
seconds
weeks
weeks
seconds
seconds
days
12
20
28
32
36
40
44
48
bytes
Portable MEDLL Manual Rev 1
7 - NovAtel Format Data Logs
WBCA/B WIDE BAND CARRIER RANGE CORRECTION
This message contains the wide band carrier range correction data. A correction is generated for each PRN being tracked
and these are grouped together into a single log. Internally, the correction for each satellite is updated asynchronously at a
1 Hz rate. Therefore, logging this message at a rate higher than 1 Hz will result in duplicate data being output. Each
carrier range correction is statistically independent and is derived from the previous 1 second of data.
WBCA
Structure:
$WBCA week seconds # obs
prn ch tr-status tr-BW
wide band carrier range correction
:
prn ch tr-status tr-BW
wide band carrier range correction *xx
Field #
1
2
3
4
Field type
$WRCA
week
seconds
# obs
Data Description
Example
$WBCA
637
513902.00
7
Log header
GPS week number
GPS seconds into the week
Number of satellite observations with information to follow:
5
6
prn
ch tr-status
7
8
tr-BW
wide band carrier correction
Satellite PRN number
Channel Tracking Status: Hexadecimal number indicating phase lock,
channel number and channel state as shown in Table 4
PLL tracking loop bandwidth in Hz
Wide band carrier range correction in cycles
..
Next observation
*xx
[CR][LF]
Checksum
Sentence terminator
9...
Variable
Variable
[CR][LF]
18
E04
15.000
0.00123
*1F
[CR][LF]
WBCB
Format:
Field #
Message ID = 97
Message byte count = 28 + (obs*16)
Bytes
Format
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
2
3
4
Week number
Seconds of week
Number of observations (obs)
4
8
4
integer
double
integer
5
6
PRN
Channel Tracking Status, see Table 4, on
Page 53
PLL tracking loop bandwidth
Wide Band Range Carrier Correction
4
4
integer
-
4
4
float
float
1
(header)
7
8
9...
Data
Units
bytes
weeks
seconds
Offset
0
3
4
8
12
16
24
-
28
32
Hz
cycles
36
40
Next observation offset = 28 + (obs#*16) where obs# = 0 to (obs – 1)
WRCA/B WIDE BAND CODE RANGE CORRECTION
This message contains the wide band code range correction data. A correction is generated for each PRN being tracked
and these are grouped together into a single log. Internally, the correction for each satellite is updated asynchronously at a
Portable MEDLL Manual Rev 1
81
7 - NovAtel Format Data Logs
1 Hz rate. Therefore, logging this message at a rate higher than 1 Hz will result in duplicate data being output. Each code
range correction is statistically independent and is derived from the previous 1 second of data.
WRCA
Structure:
$WRCA week seconds # obs
prn ch tr-status tr-BW
wide band code range correction
:
prn ch tr-status tr-BW
wide band code range correction
Field #
1
2
3
4
Field type
$WRCA
week
seconds
# obs
*xx
Data Description
Log header
GPS week number
GPS seconds into the week
Number of satellite observations with information to follow:
Example
$WRCA
637
513902.00
7
5
6
prn
ch tr-status
7
8
tr-BW
wide band range correction
Satellite PRN number
Channel Tracking Status: Hexadecimal number indicating phase
lock, channel number and channel state as shown in Table 4
DLL tracking loop bandwidth in Hz
Wide band code range correction in metres
..
Next PRN
*xx
[CR][LF]
Checksum
Sentence terminator
9...
Variable
Variable
[CR][LF]
18
E04
0.050
1.323
*1F
[CR][LF]
Example:
$WRCA, 637,513902.00,7,18,E04,0.050,1.323,
…
*1F[CR][LF]
WRCB
Format:
Field #
Message byte count = 28 + (obs*16)
Bytes
Format
Sync
Checksum
Message ID
Message byte count
3
1
4
4
char
char
integer
integer
2
3
4
Week number
Seconds of week
Number of observations (obs)
4
8
4
integer
double
integer
5
6
7
8
PRN
Channel Tracking Status
DLL tracking loop bandwidth
Wide Band Code Range Correction
4
4
4
4
integer
float
float
1
(header)
9...
82
Message ID = 67
Data
Units
bytes
weeks
seconds
Hz
metres
Offset
0
3
4
8
12
16
24
28
32
36
40
Next PRN offset = 28 + (obs*16)
Portable MEDLL Manual Rev 1
Appendix A
A
PORTABLE MEDLL
SPECIFICATIONS
RECEIVER
-
TECHNICAL
PHYSICAL
Size
Weight
448.8 x 361 x 183.5 mm (without the 19” mounting brackets)
10.2 kg
PORTABLE MEDLL RECEIVER ILLUSTRATIONS
Front
Back
Side
Portable MEDLL Manual Rev 1
83
Appendix A
ENVIRONMENTAL
Operating Temperature
Storage Temperature
Humidity
Altitude
-25° C to +65° C
-40° C to +85° C
10-80%
3,000 metres
[May operate above 3,000 m in a controlled environment, however is not certified as such.]
POWER INPUT
Connector
Voltage
Current
24V power jack
22-30 VDC
maximum 1.5 A continuous; peak 3 A
Portable MEDLL RECEIVER PERFORMANCE (Subject To GPS System Characteristics)
Frequency
Code tracked
Satellite Tracking
Channels
MEDLL
Position Accuracy Stand-alone
Time Accuracy (relative)
Pseudorange
MEDLL (L1-C/A)
Measurement
Single Channel
L1
Phase Accuracy
Raw Data
MEDLL
Availability Rate
Almanac data
Time to First Fix
Re-acquisition
Height Measurements
GPS
GEO
L1(1575.42 MHz)
GPS L1-C/A Code, GEO L1-C/A Code, GPS SVN (PRN 1-32), and GEO SVN (PRN 120-138)
12 L1-C/A
or
10 L1-C/A, 2 L1-C/A GEO
5 metres CEP (SA off), GDOP < 2
50 nanoseconds (SA off)
10 cm RMS, C/No > 44 dBHz, BW = 0.05
3 mm RMS, C/No > 44 dBHz, Loop BW = 3Hz
5 phase and code measurements per second (200 ms)
< 15 minutes after reset
100 seconds (95%) with stabilized internal oscillator.
15 minutes maximum from start of cold receiver. No initial time, almanac or position required.
5 seconds C/No = 44 dB-Hz, 10 seconds C/No = 38 dB-Hz
10 seconds C/No = 44 dB-Hz
Up to 18,288 metres (60,000 feet) maximum
[In accordance with export licensing, the card is restricted to less than 60,000 feet.]
INPUT/OUTPUT DATA INTERFACE
Serial
Connector
Electrical format
Baud rates: 300, 1200, 4800, 9600, 19200, 57600, 115200 bps, user selectable
Default: 9600 bps (COM1 and COM2)
DE9P
RS-232
OUTPUT STROBES
VARF
1PPS
MSR
84
A programmable variable frequency output ranging from 0.15 Hz to 5 MHz, with pulse width from
100 ns to 6.55 ms. This is a normally high, active low pulse. There may be as much as 50 ns
jitter on this signal.
A one-pulse-per-second Time Sync output. This is a normally high, active low pulse (200 µs for
MEDLL) where the falling edge is the reference.
Measure Output is a 1 or 5 pulses-per-second output, normally high, active low where the pulse
width is 200 µs for MEDLL. The falling edge is the receiver’s measurement strobe. (Rate is
model-dependent.)
Portable MEDLL Manual Rev 1
Appendix A
STATUS
Indicates a valid GPS position solution is available. A high level indicates a valid solution or that
the FIX POSITION command has been set, see Page 26.
DE9S
Connector
The electrical specifications of the strobe signals are as follows:
Output
Voltage
Minimum load impedance
(High) > 2.0 VDC
1 KW
(Low) < 0.55 VDC
ANTENNA INPUT
Connector
Frequency
Power
Noise Power Spectral Density
Maximum C/N0
TNC female
L1(1575.42 MHz),
2.1 mm plug (10 – 36 VDC) centre positive
-140 dBm/Hz to -160 dBm/Hz
65 dB-Hz
DEFAULT CHANNEL ASSIGNMENTS – Portable MEDLL RECEIVER
Port
COM1
Channel
0
1
2
3
4
5
6
7
8
9
10
11
SV Type
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
Code
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
DLL Type
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
Port
COM1
Channel
0
1
2
3
4
5
6
7
8
9
10
11
SV Type
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GEO
GEO
Code
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
L1 C/A
DLL Type
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
MEDLL
Frame
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
Nav Type
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
Symbol Rate
50
50
50
50
50
50
50
50
50
50
50
50
FEC
No
No
No
No
No
No
No
No
No
No
No
No
Sky Search
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Frame
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GEO
GEO
Nav Type
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GPS
GEO
GEO
Symbol Rate
50
50
50
50
50
50
50
50
50
50
500
500
FEC
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Sky Search
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Idle
Idle
Or
Portable MEDLL Manual Rev 1
85
Appendix B
B
GPS OVERVIEW
The Global Positioning System (GPS) is a satellite system capable of providing independent and highly accurate timing
and positioning information. GPS provides 24-hour, all-weather, worldwide coverage. Refer to Figure 13 for a
representation of the GPS satellite orbit arrangement.
Figure 13
View of GPS Satellite Orbit Arrangement
GPS SYSTEM DESIGN
The system uses the NAVSTAR (NAVigation Satellite Timing And Ranging) satellites that consist of 24 operational
satellites. A minimum of four satellites in view allows the GPSCard to compute its current latitude, longitude, altitude
with reference to ellipsoid mean sea level and the GPS system time.
The GPS system design consists of three parts:
·
The Space segment
·
The Control segment
·
The User segment
All these parts operate together to provide accurate three-dimensional positioning, timing and velocity data to users
worldwide.
86
Portable MEDLL Manual Rev 1
Appendix B
THE SPACE SEGMENT
The space segment is composed of the NAVSTAR GPS satellites. The specified constellation of the system consists of 24
satellites in six orbital planes, inclined 55° from the equator, with four satellites in each plane. The orbital period of each
satellite is approximately 12 hours at an altitude of 20,183 km.
The GPS satellite signal identifies the satellite and provides the positioning, timing, ranging data, satellite status and
ephemerides (orbit parameters) of the satellite to the receiver. The satellites can be identified either by the Space Vehicle
Number (SVN) or the Pseudorandom Code Number (PRN). The PRN is used by the NovAtel GPSCard.
The GPS satellites transmit on two L-band frequencies; one centred at 1575.42 MHz (L1) and the other at 1227.60 MHz
(L2). The L1 carrier is modulated by the C/A code (Coarse/Acquisition) and the P-Code (Precision) that is encrypted for
military and other authorized users. The L2 carrier is modulated only with the P-Code. Please refer to Figure 13, View of
GPS Satellite Orbit Arrangement, on the previous page, for a representation of the GPS satellite orbit arrangement.
THE CONTROL SEGMENT
The control segment consists of a master control station, five reference stations and three data up-loading stations in
locations all around the globe.
The reference stations track and monitor the satellites via their broadcast signals. The broadcast signals contain the
ephemeris data of the satellites, the ranging signals, the clock data and the almanac data. These signals are passed to the
master control station where the ephemerides are re-computed. The resulting ephemerides corrections and timing
corrections are transmitted back to the satellites via the data up-loading stations.
THE USER SEGMENT
The user segment such as the Portable MEDLL receiver, consists of equipment, which tracks and receives the satellite
signals. The user equipment must be capable of simultaneously processing the signals from a minimum of four satellites
to obtain accurate position, velocity and timing measurements.
Portable MEDLL Manual Rev 1
87
Appendix C
C
INFORMATION MESSAGES
While operating the Portable MEDLL receiver, there may be additional messages output by the receiver that you may
observe. This information is in addition to typical log data as described in this manual, and falls into two categories:
Type 1:
Messages that occur as a result of an operational error within the receiver over which you have no control.
These appear in typical NovAtel log format.
Type 2:
Messages that occur in response to your input. These are not in typical log format.
The following sections describe these messages.
TYPE 1 INFORMATION MESSAGES
As mentioned, Type 1 information messages indicate that there is a problem with the operation of the on-board firmware.
To date, the only Type 1 messages in use are the !ERRA and the !MSGA logs.
If you receive the !ERRA message, it may be useful to reload the software using the correct authorization code; see Table
15, Page 88 for a list of !ERRA message types. Each of these messages causes a “severity fatal” condition to be set,
causing the card to be reset. To reload the software, power down the receiver and follow the procedure outlined in
Chapter 4. Under certain error conditions, the card will reset itself and resolve the difficulty.
If, after verifying that the software has been correctly loaded, and the receiver cannot reset itself to function normally, the
receiver requires maintenance.
The !MSGA log would be output if the software is a time-limited version. The log will provide the expiry date of the
software. See Table 16, on Page 89, for a list of !MSGA message types. Portable MEDLL receivers are not time limited.
There will be no expiry date.
!ERRA
!ERRA
Field #
type
severity
Field type
1
2
3
!ERRA
type
severity
4
5
error string
opt desc
*xx
[CR][LF]
6
7
error string
opt desc
*xx [CR][LF]
Data Description
Example
Log header
Log type, numbered 0 - 8 (see Table 15, Page 88)
Only one is defined to date: severity_fatal (number = 0); causes the receiver
to be reset
Error message (see Table 15, Page 88)
Optional additional description
Checksum
Sentence terminator
!ERRA
1
0
Authorization code invalid
*22
[CR][LF]
Example:
!ERRA,1,0,Authorization Code Invalid,*22[CR][LF]
Table 15 Type 1 !ERRA Messages
Log type
0
1
2
3
4
88
Error String
Unknown ERRA Type
Authorization Code Invalid
No Authorization Code Found
Invalid Expiry In Authorization Code
Unable To Read ESN
Portable MEDLL Manual Rev 1
Appendix C
6
7
8
Card Has Stopped Unexpectedly
Incorrect Number of Cards Found
Software Version Mismatch
!MSGA
!MSGA
Field #
1
2
3
4
5
6
type
message
opt desc
Field type
!MSGA
type
message
opt. description
*xx
[CR][LF]
*xx [CR][LF]
Data Description
Log header
Log type, numbered from 1000 (see Table 16)
Message (see Table 16)
Optional description
Checksum
Sentence terminator
Example
!MSGA
1001
Authorization Code is Time Limited
Model 3951R expires on 960901
*6C
[CR][LF]
Example:
!MSGA,1001,Authorization Code Is Time Limited, Model 3951R Expires on 960901
*6C[CR][LF]
Table 16 Type 1 !MSGA Messages
Log type
1000
1001
Portable MEDLL Manual Rev 1
Message String
Unknown MSGA Type
Authorization Code Is Time Limited
89
Appendix C
TYPE 2 INFORMATION MESSAGES
NOTE:
Commands referred to in the information messages that do not appear in this manual may be found in a
NovAtel Command Descriptions manual.
The following is a list of information messages that are generated by the Command Interpreter in the receiver in response
to your input. This list is not necessarily complete, but it is the most accurate one available at the time of publication.
Table 17
Error Message
All OK
Argument Must Be Hexadecimal (0-9,A-F) Pairs
Argument Must Be Numeric
Authorization Changes Not Available On This Card
Authorization Code Entered Incorrectly
Authorization Code Is Invalid
Can't Change Authorization Code
Clock Model not set TM1A rejected
CLOCK_ADJUST Command Not Available On This Model
Complete Almanac not received yet - try again later
Data Too Large To Save To NVM
Differential Corrections Not Available On This Model
EXTERNALCLOCK Command Not Available On This Model
FREQUENCY_OUT Command Not Available On This Model
FROM port name too LONG
Invalid $ALMA Checksum
Invalid $IONA Checksum
Invalid $REPA Checksum
Invalid $TM1A Checksum
Invalid $UTCA Checksum
Invalid ADJUSTCLOCK Option
Invalid Baud Rate
Invalid Code Smoothing Constant
Invalid Channel Number
Invalid Command CRC
Invalid Command Name
Invalid Command Option
Invalid Datatype
Invalid Datum Offset
Invalid DATUM Option
Invalid Datum Rotation
Invalid Degree Field
Invalid Doppler
90
Type 2 Information Messages
Meaning
No errors to report.
An argument which is not hexadecimal was entered.
An argument which is not numeric was entered.
An attempt has been made to change the Authorization Code on a card, which is
not an OEM card.
The checksum is incorrect for the Authorization Code. The Authorization Code was
most likely entered incorrectly.
The existing Authorization Code is invalid. Please contact NovAtel for a new
Authorization Code.
The existing Authorization Code cannot be changed. Please contact NovAtel for
assistance.
The clock model status in a $TM1A command is invalid. The $TM1A command is
rejected when the clock model has not been set.
The CLOCKADJUST command is not available on this model.
The almanac cannot be saved because a complete almanac has not yet been
received. A SAVEALMA command should be performed at a later time when a
complete almanac has been received.
The configuration data being saved is too large.
This model does not have the ability to send or receive differential corrections.
The EXTERNALCLOCK command is not available on this model.
The FREQUENCY_OUT command is not available on this model.
The FROM port name in a SETNAV command is too long.
The checksum of a $ALMA command is invalid.
The checksum of a $IONA command is invalid.
The checksum of a $REPA command is invalid.
The checksum of a $TM1A command is invalid.
The checksum of a $UTCA command is invalid.
An invalid CLOCKADJUST switch has been entered.
The baud rate in a COM1 command is invalid.
The code smoothing constant of the CSMOOTH command is invalid.
An invalid channel number has been entered in a command such as ASSIGN.
The received command has an invalid checksum.
An invalid command name has been received.
One or more arguments of a command are invalid.
The data type in an ACCEPT command is invalid.
The datum offset in a USERDATUM command is invalid.
An option in a DATUM command is invalid.
The datum rotation angle in a USERDATUM command is invalid.
An invalid degree field has been entered in a command such as FIX POSITION.
An invalid Doppler has been entered in an ASSIGN command.
Portable MEDLL Manual Rev 1
Appendix C
Invalid Doppler Window
Invalid DYNAMICS Option
Invalid Echo Option
Invalid Elevation Cutoff Angle
Invalid EXTERNALCLOCK Option
Invalid EXTERNALCLOCK USER Argument(s)
Invalid FIX Option
Invalid Flattening
Invalid Handshake Option
Invalid HEALTH Override
Invalid Height
Invalid Logger Datatype
Invalid Logger Offset
Invalid Logger Period
Invalid Logger Port Option
Invalid Logger Trigger
Invalid Number of $ALMA Arguments
Invalid Number of $IONA Arguments
Invalid Number of $REPA Arguments
Invalid Number of $TM1A Arguments
Invalid Number of $UTCA Arguments
Invalid Number of Arguments
Invalid Number of Databits
Invalid Number of StopBits
Invalid Parity Option
Invalid Port
Invalid Port number
Invalid RTCA station Name (\XXXX\)
Invalid Satellite Number
Invalid Scaling
Invalid Seconds Into Week in TM1A
Invalid SemiMajor Axis
Invalid Symbol Period 1,2,4,5,10,20
Invalid Token
Invalid Week Number in TM1A
MET Command Not Available On This Model
Model Invalid
RT20 Logs Not Available On This Model
RTCM9 Logs Not Available On This Model
SETCLOCK disabled TM1A rejected
User Defined DATUM Not Set
Valid Option but Missing Process
An invalid Doppler window has been entered in an ASSIGN command.
The option in a DYNAMICS command is invalid.
The echo option in a COM1 command is invalid.
The elevation cut-off angle in an ECUTOFF command is invalid.
An invalid external clock was entered in the EXTERNALCLOCK command.
An invalid argument was entered in the EXTERNALCLOCK command.
An option other than height, position or velocity was specified in a FIX command.
The flattening in a USERDATUM command is invalid.
The handshake option in a COM1 command is invalid.
An invalid health has been entered in a SETHEALTH or FIX command.
The height in a FIX HEIGHT command is invalid.
An invalid log has been specified in a LOG/UNLOG command.
An invalid offset has been specified in a LOG command.
An invalid period has been specified in a LOG command.
An invalid port number has been specified in a LOG/UNLOG command.
An invalid trigger has been specified in a LOG command.
The number of arguments in a $ALMA command is invalid.
The number of arguments in a $IONA command is invalid.
The number of arguments in a $REPA command is invalid.
The number of arguments in a $TM1A command is invalid.
The number of arguments in a $UTCA command is invalid.
A command has been received which has an invalid number of arguments.
The number of data bits in a COM1 command is invalid.
The number of stop bits in a COM1 command is invalid.
The parity in a COM1 command is invalid.
The port in a SEND command is invalid.
The port number in an ACCEPT command is invalid.
The RTCA station name in a FIX POSITION message is invalid.
An invalid satellite number has been entered in an ASSIGN command.
The scale value in a USERDATUM command is invalid.
The time in a $TM1A command is invalid.
The semi-major axis in a USERDATUM command is invalid.
The symbol period is invalid for an ASSIGN on a pseudolite channel.
This error should never occur. If it does, please contact NovAtel.
The week in a $TM1A command is invalid.
The MET command is not available on this model.
The Authorization Code has an invalid Model. Please contact NovAtel for help.
This model is not able to send or receive RT20 differential corrections.
This model does not have the ability to send or receive RTCM9 logs.
The $TM1A command is rejected because the user has not enabled clock
synchronization using the SETCLOCK command.
This error should not occur. By default the user defined DATUM is set to WGS-84.
If you get this error message, please contact NovAtel GPS .
This message indicates an error in the software. A command option is valid but
software cannot process it
Example:
Argument Must Be Numeric
Portable MEDLL Manual Rev 1
91
Appendix D
D
ACRONYMS
1PPS
One Pulse Per Second
A
A/D
ADR
AGC
ANT
ASCII
ASIC
Ampere(s)
Analog-to-Digital
Accumulated Doppler Range
Automatic Gain Control
Antenna
American Standard Code for Information Interchange
Application Specific Integrated Circuits
BIST
BIT
Built-In-Self-Test
Built-In Test
bps
Bits per Second
C/A Code
CEP
CPU
CR
CRC
CTS
Coarse/Acquisition Code
Circular Error Probable
Central Processing Unit
Carriage Return
Cyclic Redundancy Check
Clear To Send
dB
DC
DCD
DGPS
DLL
DOP
DSP
DSR
DTR
Decibel
Direct Current
Data Carrier Detected
Differential Global Positioning System
Delay Lock Loop
Dilution Of Precision
Digital Signal Processor
Data Set Ready
Data Terminal Ready
EGNOS
ESD
European Geostationary Navigation Overlay Service
Electrostatic Discharge
FEC
Forward Error Correction
GDOP
GEO
GMT
GND
GPS
Geometric Dilution Of Precision
Geostationary Satellite
Greenwich Mean Time
Ground
Global Positioning System
hex
Hz
Hexadecimal
Hertz
ICD
I/O
IODE
Interface Control Document
Input/Output
Issue of Data (Ephemeris)
L1
L2
LED
1575.42 MHz GPS carrier frequency, C/A and P-Code
1227.60 MHz GPS carrier frequency, P-Code
Light-Emitting Diode
92
Portable MEDLL Manual Rev 1
Appendix D
LF
LNA
Line Feed
Low Noise Amplifier
MAT
MCC
MET
MEDLL
MHz
MINOS
MKI
MOPS
MSL
MSR
Multipath Assessment Tool
Master Control Centres
Multipath Elimination Technology
Multipath Estimating Delay Lock Loop
Megahertz or one million Hertz
Multiple Independent Nomadic Stargazer
Mark In
Minimum Operational Performance Standards
Mean sea level
Measurement
NAVSTAR
NC
NLES
ns
NAVigation Satellite Timing And Ranging (synonymous with GPS)
Not Connected
Navigation Land Earth Stations
nanosecond
OCXO
OEM
Oven Controlled Crystal Oscillator
Original Equipment Manufacturer
PC
P-Code
PLL
PPS
PRN
Personal Computer
Precise Code
Phase Lock Loop
Pulse Per Second
Pseudo Random Noise number
RAM
RIMS
RF
ROM
RT
RTCA
RTCM
RTS
RXD
Random Access Memory
Ranging and Integrity Monitoring Stations
Radio Frequency
Read Only Memory
Receive Time
Radio Technical Commission for Aviation Services
Radio Technical Commission for Maritime Services
Request To Send
Received Data
SA
SPS
SV
SVN
Selective Availability
Standard Positioning Service
Space Vehicle
Space Vehicle Number
TCXO
TT
TXD
Temperature Controlled Crystal Oscillator
Transmit Time
Transmitted Data
UART
UTC
Universal Asynchronous Receiver Transmitter
Universal Time Coordinated
V
Volt(s)
WGS
World Geodetic System
Portable MEDLL Manual Rev 1
93
Index
INDEX
1
1PPS, 80
A
accumulated Doppler, 67
almanac, 17, 41, 88
amplitude, 58, 59
antenna, 7, 26, 60
ASCII format, 37, 38
azimuth, 76
B
batch file, 13
binary, 37, 59
broadcast, 88
C
C/A code, 88
C/N0, 67
carrier phase, 67
case sensitive, 15
channel, 67, 82, 83
configuration, 23
state, 67, 82, 83
tracking status, 58
checksum, 37
clock, 21, 45, 49, 80, 88
COM1, 10, 15, 22, 28
comma, 15
communications settings, 9
constellation, 88
control segment, 87, 88
correlator, 58
ephemeris, 88
F
front panel, 6, 10
G
G2 delay, 20
GDOP, 49
geodetic datum, 61
GPS time, 38
H
HDOP, 49
health, 17, 41
HTDOP, 49
I
idle time, 37
in phase residual, 58
ionospheric, 41, 56, 81
L
latitude, 87
L-band, 88
locktime, 67
longitude, 87
M
master control station, 88
mean sea level, 87
MEDLL, 8, 58, 59
MPM log (multipath meter), 58
multipath information, 58
D
D/U ratio, 59
datum, 62, 63
delay, 58
Doppler, 67
E
echo response, 11
elevation, 25, 39, 76, 82, 83
ellipsoid, 61, 62, 63
94
N
navigation, 87
NAVSTAR, 87, 88
non-volatile memory, 9
O
orbit period, 88
output pulse, 27
Portable MEDLL Manual Rev 1
Index
P
MEDLL, 58, 59
receiver, 10, 70, 74
strobe lines, 8
subframes, 17, 41
PDOP, 49
phase, 58
lock, 67, 82, 83
port
antenna, 7
power, 7
serial, 6, 9, 10, 11
position constraints, 34
power
antenna, 86
input, 7, 85
MEDLL, 3
supply, 4, 9
processing, 88
T
TDOP, 49
time
conventions, 38
GPS, viii
of 1PPS, 80
receive and transmit, 10
receiver, 45
smoothing, 24
start-up, 9
tracking status, 67
transformation, 61
trigger option, 58
Type 1 information messages, 89
Type 2 information messages, 91
Q
quadrature phase residual, 58
R
U
reject code, 76
residuals, 58, 59, 76
upgrading, 12
user segment, 87, 88
UTC, 38, 41, 80, 81
S
self-test, 67
space, 15
segment, 87, 88
status
OM-20000057
V
VARF, 27
velocity, 87, 88
Rev 1
2002/06/21
Index
NovAtel Inc.
1120 - 68 Avenue N.E.
Calgary, Alberta, Canada T2E 8S5
GPS Hotline: 1-403-295-4900
GPS Fax: 1-403-295-4901
E-mail: mailto:support@novatel.ca
Web site: http://www.novatel.ca/
96
Recyclable
Printed in Canada
on recycled paper
Portable MEDLL Manual Rev 1
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