Garmin 15L GPS Receiver User Manual

GPS 15H & 15L
TECHNICAL
SPECIFICATIONS
®
Garmin International, Inc.
1200 E. 151st Street
Olathe, KS 66062 USA
190-00266-01, Revision D
February 2006
© Copyright 2004–2006 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street, Olathe, Kansas 66062, U.S.A.
Tel. 913/397.8200 or 800/800.1020
Fax 913/397.8282
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9DL, U.K.
Tel. 44/0870.8501241
Fax 44/0870.8501251
Garmin Corporation
No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
Tel. 886/2.2642.9199
Fax 886/2.2642.9099
All rights reserved. Except as expressly provided herein, no part of this manual may be reproduced, copied,
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express prior written consent of Garmin. Garmin hereby grants permission to download a single copy of
this manual onto a hard drive or other electronic storage medium to be viewed and to print one copy of this
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the complete text of this copyright notice and provided further that any unauthorized commercial
distribution of this manual or any revision hereto is strictly prohibited.
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organization of such changes or improvements. Visit the Garmin Web site (www.garmin.com) for current
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Garmin®, AutoLocate®, and MapSource® are registered trademarks and WAAS Enabled™ is trademark of
Garmin Ltd. or its subsidiaries and may not be used without the express permission of Garmin.
Web site address: www.garmin.com
RECORD OF REVISIONS
Revision
A
B
C
D
190-00266-01
Revision
Date
8/16/02
10/22/04
12/27/04
2/17/06
Description
Initial Release
Revised and Redrawn
Revised and Redrawn
Revised and Redrawn
GPS 15H & 15L Technical Specifications
Page ii
ECO #
-28110
28960
36010
Rev. D
TABLE OF CONTENTS
1
Introduction..................................................................................................................1
1.1 Cautions ............................................................................................................................................1
1.2 Limited Warranty ..............................................................................................................................2
1.3 Overview...........................................................................................................................................3
1.4 Features .............................................................................................................................................3
1.5 Technical Specifications ...................................................................................................................4
1.5.1 Physical Characteristics......................................................................................................................... 4
1.5.1.1 Size............................................................................................................................................ 4
1.5.1.2 Weight ....................................................................................................................................... 4
1.5.1.3 Available Connector Options .................................................................................................... 4
1.5.1.4 Antenna Connector.................................................................................................................... 4
1.5.2 Electrical Characteristics....................................................................................................................... 4
1.5.2.1 Input Voltage............................................................................................................................. 4
1.5.2.2 Input Current ............................................................................................................................. 4
1.5.2.3 GPS Receiver Sensitivity .......................................................................................................... 4
1.5.3 Environmental Characteristics............................................................................................................... 4
1.5.4 GPS Performance .................................................................................................................................. 5
1.5.4.1 Receiver..................................................................................................................................... 5
1.5.4.2 Acquisition Times ..................................................................................................................... 5
1.5.4.3 Update Rate ............................................................................................................................... 5
1.5.4.4 Accuracy ................................................................................................................................... 5
1.5.5 Interfaces............................................................................................................................................... 6
1.5.5.1 GPS 15H & 15L Electrical Characteristics................................................................................ 6
1.5.5.2 Port 1 Protocols ......................................................................................................................... 6
1.5.5.3 Port 2 Protocols ......................................................................................................................... 6
1.5.5.4 PPS ............................................................................................................................................ 6
1.5.6 Antenna Specifications.......................................................................................................................... 6
2
GPS 15H & 15L Wire Descriptions and Wiring Diagrams .....................................8
2.1 GPS 15H & 15L Wire Descriptions ..................................................................................................8
2.2 GPS 15H & 15L Wiring Diagrams ...................................................................................................9
3
Mechanical Characteristics & Mounting.................................................................10
4
GPS 15H & 15L Software Interface.........................................................................11
4.1 Received NMEA 0183 Sentences ...................................................................................................11
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
Almanac Information (ALM) ...............................................................................................................11
Sensor Initialization Information (PGRMI)..........................................................................................12
Sensor Configuration Information (PGRMC) ......................................................................................12
Additional Sensor Configuration Information (PGRMC1) ..................................................................13
Output Sentence Enable/Disable (PGRMO) ........................................................................................13
Tune DGPS Beacon Receiver (PSLIB) ................................................................................................14
4.2 Transmitted NMEA 0183 Sentences...............................................................................................15
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6
4.2.7
4.2.8
4.2.9
4.2.10
4.2.11
190-00266-01
Sentence Transmission Rate.................................................................................................................15
Transmitted Time .................................................................................................................................16
Global Positioning System Almanac Data (ALM) ...............................................................................16
Global Positioning System Fix Data (GGA) ........................................................................................16
GPS DOP and Active Satellites (GSA) ................................................................................................17
GPS Satellites in View (GSV)..............................................................................................................17
Recommended Minimum Specific GPS/TRANSIT Data (RMC) ........................................................17
Track Made Good and Ground Speed (VTG) ......................................................................................17
Geographic Position (GLL)..................................................................................................................18
Estimated Error Information (PGRME) ...............................................................................................18
GPS Fix Data Sentence (PGRMF) .......................................................................................................18
GPS 15H & 15L Technical Specifications
Page iii
Rev. D
4.2.12
4.2.13
4.2.14
4.2.15
Map Datum (PGRMM) ........................................................................................................................18
Sensor Status Information (PGRMT) ...................................................................................................19
3D velocity Information (PGRMV) .....................................................................................................19
DGPS Beacon Information (PGRMB) .................................................................................................19
4.3 Baud Rate Selection ........................................................................................................................20
4.4 One-Pulse-Per-Second (PPS) Output ..............................................................................................20
4.5 Received RTCM Data .....................................................................................................................20
Appendix A: Earth Datums ............................................................................................21
Appendix B: Binary Phase Output Format...................................................................24
Satellite Data Record .......................................................................................................................................24
Position Record ................................................................................................................................................26
Receiver Measurement Record ........................................................................................................................26
Sample C Code ................................................................................................................................................27
Appendix C: Changing the Baud Rate in Garmin Mode.............................................28
Appendix D: Ephemeris Data Download (Programming Example)...........................29
Synopsis ...........................................................................................................................................................29
Garmin Binary Format Review ........................................................................................................................29
Ephemeris Download Procedure ......................................................................................................................30
TX Packet: Ephemeris Data Request .......................................................................................................30
RX Packet: Acknowledgement ................................................................................................................30
RX Packet: Number of Data Packets to Expect........................................................................................30
TX Packet: Acknowledgement.................................................................................................................30
RX Packet: Ephemeris Data .....................................................................................................................31
TX Packet: Download Complete..............................................................................................................33
Appendix E: Declaration of Conformity........................................................................34
LIST OF TABLES AND FIGURES
Table 1: Gain vs. SNR for Given Noise Figure.............................................................................................. 7
Table 2: GPS 15H & 15L Wire Descriptions ................................................................................................. 8
Figure 1: Computer Serial Port Interconnection............................................................................................. 9
Figure 2: PDA Serial Port Interconnection..................................................................................................... 9
Figure 3: Basic NMEA Device Interconnection............................................................................................. 9
Figure 4: GPS 15H-F & 15L-F Dimensions................................................................................................. 10
Figure 5: GPS 15H-W & 15L-W Outline Drawing...................................................................................... 10
Table 3: NMEA 0183 Output Sentence Order and Size ............................................................................... 15
Table 4: Characters per Second for Available Baud Rates........................................................................... 15
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GPS 15H & 15L Technical Specifications
Page iv
Rev. D
1
INTRODUCTION
1.1
CAUTIONS
Caution
The GPS system is operated by the government of the United States, which is solely responsible for its
accuracy and maintenance. Although the GPS 15H & 15L sensors are precision electronic NAVigation
AIDs (NAVAID), any NAVAID can be misused or misinterpreted, and therefore become unsafe. Use these
products at your own risk. To reduce the risk, carefully review and understand all aspects of these
Technical Specifications before using the GPS 15H & 15L. When in actual use, carefully compare
indications from the GPS to all available navigation sources including the information from other
NAVAIDs, visual sightings, charts, etc. For safety, always resolve any discrepancies before continuing
navigation.
FCC
Compliance
The GPS 15H & 15L sensors comply with Part 15 of the FCC interference limits for Class B digital devices
FOR HOME OR OFFICE USE. These limits are designed to provide reasonable protection against harmful
interference in a residential installation, and are more stringent than “outdoor” requirements.
Operation of this device is subject to the following conditions: (1) This device may not cause harmful
interference, and (2) this device must accept any interference received, including interference that may
cause undesired operation.
This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications. However, there
is no guarantee that interference will not occur in a particular installation. If this equipment does cause
harmful interference to radio or television reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference by one or more of the following measures:
•
Reorient or relocate the receiving antenna.
•
Increase the separation between the equipment and receiver.
•
Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
•
Consult the dealer or an experienced radio/TV technician for help.
The GPS 15H & 15L sensors do not contain any user-serviceable parts. Unauthorized repairs or
modifications could result in permanent damage to the equipment and void your warranty and your
authority to operate these devices under Part 15 regulations.
190-00266-01
GPS 15H & 15L Technical Specifications
Page 1
Rev. D
1.2
LIMITED WARRANTY
This Garmin product is warranted to be free from defects in materials or workmanship for one year from
the date of purchase. Within this period, Garmin will at its sole option repair or replace any components
that fail in normal use. Such repairs or replacement will be made at no charge to the customer for parts or
labor, provided that the customer shall be responsible for any transportation cost. This warranty does not
cover failures due to abuse, misuse, accident, or unauthorized alteration or repairs.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN LIEU OF
ALL OTHER WARRANTIES EXPRESS OR IMPLIED OR STATUTORY, INCLUDING ANY
LIABILITY ARISING UNDER ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE, STATUTORY OR OTHERWISE. THIS WARRANTY GIVES YOU
SPECIFIC LEGAL RIGHTS, WHICH MAY VARY FROM STATE TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT OR
CONSEQUENTIAL DAMAGES, WHETHER RESULTING FROM THE USE, MISUSE, OR
INABILITY TO USE THIS PRODUCT OR FROM DEFECTS IN THE PRODUCT. Some states do not
allow the exclusion of incidental or consequential damages, so the above limitations may not apply to you.
Garmin retains the exclusive right to repair or replace the unit or software or offer a full refund of the
purchase price at its sole discretion. SUCH REMEDY SHALL BE YOUR SOLE AND EXCLUSIVE
REMEDY FOR ANY BREACH OF WARRANTY.
To obtain warranty service, contact your local Garmin authorized dealer or call Garmin Product Support at
one of the numbers listed below for shipping instructions and an RMA tracking number. The unit should be
securely packed with the tracking number clearly written on the outside of the package. The unit should
then be sent, freight charges prepaid, to any Garmin warranty service station. A copy of the original sales
receipt is required as the proof of purchase for warranty repairs.
Garmin International, Inc.
1200 E 151st Street, Olathe, Kansas 66062 U.S.A.
Tel. 913/397.8200 or 800/800.1020
Fax. 913/397.8282
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9DL U.K.
Tel. 44/0870.8501241
Fax 44/0870.8501251
Online Auction Purchases: Products sold through online auctions are not eligible for rebates or other
special offers from Garmin. Online auction confirmations are not accepted for warranty verification. To
obtain warranty service, an original or copy of the sales receipt from the original retailer is required.
Garmin will not replace missing components from any package purchased through an online auction.
International Purchases: A separate warranty is provided by international distributors for units purchased
outside the United States. This warranty is provided by the local in-country distributor and this distributor
provides local service for your unit. Distributor warranties are only valid in the area of intended
distribution. Units purchased in the United States or Canada must be returned to the Garmin service center
in the United Kingdom, the United States, Canada, or Taiwan for service.
190-00266-01
GPS 15H & 15L Technical Specifications
Page 2
Rev. D
1.3
OVERVIEW
The GPS 15H & 15L are part of Garmin’s latest generation of GPS sensor boards designed for a broad
spectrum of OEM (Original Equipment Manufacture) system applications. Based on the proven technology
found in other Garmin 12-channel GPS receivers, the GPS 15H & 15L track up to 12 satellites at a time
while providing fast time-to-first-fix, one-second navigation updates, and low power consumption. The
GPS 15H & 15L also provide the capability of FAA Wide Area Augmentation System (WAAS) differential
GPS. Their far-reaching capabilities meet the sensitivity requirements of land navigation, the timing
requirements for precision timing applications, as well as the dynamics requirements of high-performance
aircraft.
The GPS 15H & 15L designs utilize the latest technology and high-level circuit integration to achieve
superior performance while minimizing space and power requirements. Critical components of the system,
such as the digital baseband processor, were designed by Garmin to ensure that the GPS 15H & 15L
provide the quality, performance, and capabilities that you have grown to expect from Garmin GPS
receivers. The elegant hardware design, combined with software intelligence, makes the GPS 15H & 15L
easy to integrate and use.
Because they are complete GPS receivers, the GPS 15H & 15L require minimal additional components
from an OEM or system integrator. A minimum system must provide the GPS receiver with a source of
power, a GPS antenna, and a clear view of GPS satellites within the 1.5 GHz band. For optimum
performance, the GPS antenna should be an active antenna with a gain between 10 and 30 dB. If cost
constraints prevent the use of an active antenna, a well-matched, efficient, passive antenna attached by a
short cable can be used instead.
The system may communicate with the GPS 15H & 15L via two RS-232 compatible receive channels and
one transmit channel. The GPS 15H & 15L internal FLASH memory allows the GPS to retain critical data
such as satellite orbital parameters, last-known position, date and time. End-user interfaces such as
keyboards and displays are the responsibility of the application designer.
1.4
FEATURES
•
12-channel GPS receiver tracks and uses up to 12 satellites for fast, accurate positioning and low
power consumption.
•
Differential DGPS capability utilizing real-time WAAS or RTCM corrections yielding 3–5 meter
position accuracy (see section 1.5.4.4).
•
Compact, rugged design ideal for applications with minimal space.
•
May be remotely mounted in an out-of-the-way location.
•
Receiver status information can be displayed directly on a chartplotter or PC.
•
User initialization is not required. Once installed and a fix is obtained, the unit automatically
produces navigation data.
•
User-configurable navigation mode (2-dimensional or 3-dimensional fix).
•
Highly accurate one-pulse-per-second (PPS) output for precise timing measurements. Pulse width
is configurable in 20 millisecond increments from 20 ms to 980 ms.
•
Configurable for binary format carrier phase data output on COM 1 port.
•
Flexible input voltage levels of 3.3 to 5.4 VDC (GPS 15L) or 8.0 to 40 VDC (GPS 15H).
•
Built-in backup battery to maintain real-time clock for up to 21 days. Provision for external power
to maintain the real-time clock for longer intervals.
•
FLASH-based program and non-volatile memory. New software revisions upgradeable through
Web site download and serial interface. Non-volatile memory does not require battery backup.
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GPS 15H & 15L Technical Specifications
Page 3
Rev. D
1.5
TECHNICAL SPECIFICATIONS
Specifications are subject to change without notice.
1.5.1
Physical Characteristics
1.5.1.1 Size
1.400” (35.56 mm) wide x 1.805” (45.85 mm) long x 0.327” (8.31 mm) high
1.5.1.2 Weight
• GPS 15H:
•
GPS 15L:
0.53 oz. (15.0 g)
0.50 oz (14.1 g)
1.5.1.3 Available Connector Options
• GPS 15H-F & 15L-F: 8-pin LIF (Low Insertion Force) flex connector, 1-millimeter pitch. For use
with common 1 mm pitch, 8-conductor flex cable, available as Garmin Part
Number 310-00040-01. This flex cable mates with common 1 mm pitch, 8pin flex connectors, such as Garmin Part Number 330-00346-08 or Molex
Part Number 52793-0890. Refer to the Molex Web site at www.molex.com.
•
GPS 15H & 15L-W: 8-pin JST connector, 1-millimeter pitch. Mating wire harness included
(Garmin Part Number 325-00118-01). The connector housing used on this
harness is equivalent to JST Part Number SHR-08V-S-B. The 8-wire crimp
socket is equivalent to JST Part Number SSH-003T-P0.2. Refer to the JST
Web site at www.jst.com.
1.5.1.4 Antenna Connector
The GPS 15H & 15L sensors provide a MCX female connector for connection to an active GPS antenna, so
the antenna’s cable should be terminated in MCX male. A suitable antenna is Garmin’s GA 27C Antenna
(Garmin Part Number 010-10052-05). Other antennas that are terminated in male BNC connectors may be
adapted via a Garmin MCX to BNC Adapter Cable (Garmin Part Number 010-10121-00).
1.5.2
Electrical Characteristics
1.5.2.1 Input Voltage
• GPS 15H:
8.0 VDC to 40 VDC unregulated
•
GPS 15L:
3.3 VDC to 5.4 VDC (must have less than 100 mV peak-to-peak ripple)
1.5.2.2 Input Current
• GPS 15H:
60 mA peak, 50 mA nominal @ 8.0 VDC
40 mA peak, 33 mA nominal @ 12 VDC
15 mA peak, 12 mA nominal @ 40 VDC
•
GPS 15L:
100 mA peak, 85 mA nominal @ 3.3 to 5.0 VDC
1.5.2.3 GPS Receiver Sensitivity
-165 dBW minimum
1.5.3
Environmental Characteristics
•
Operating Temperature:
-30°C to +80°C
•
Storage Temperature:
-40°C to +90°C
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GPS 15H & 15L Technical Specifications
Page 4
Rev. D
1.5.4
GPS Performance
1.5.4.1 Receiver
WAAS Enabled™, 12 parallel channel GPS receiver continuously tracks and uses up to 12 satellites (up to
11 with PPS active) to compute and update your position.
1.5.4.2 Acquisition Times
• Reacquisition: Less than 2 seconds
•
Warm:
Approx. 15 seconds (all data known)
•
Cold:
Approx. 45 seconds (initial position, time, and almanac known; ephemeris unknown)
•
AutoLocate®:
5 minutes (almanac known; initial position and time unknown)
•
SkySearch:
5 minutes (no data known)
1.5.4.3 Update Rate
1 second default; NMEA 0183 output interval configurable from 1 to 900 seconds in 1-second increments.
1.5.4.4 Accuracy
• GPS Standard Positioning Service (SPS)
Position: < 15 meters, 95% typical
Velocity: 0.1 knot RMS steady state
•
DGPS (USCG/RTCM)
Position: 3-5 meters, 95% typical
Velocity: 0.1 knot RMS steady state
•
DGPS (WAAS)
Position: < 3 meters, 95% typical
Velocity: 0.1 knot RMS steady state
•
PPS Time: ±1 microsecond at rising edge of PPS pulse (subject to Selective Availability)
•
Dynamics: 999 knots velocity (only limited at altitude greater than 60,000 feet), 6g dynamics
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GPS 15H & 15L Technical Specifications
Page 5
Rev. D
1.5.5
Interfaces
1.5.5.1 GPS 15H & 15L Electrical Characteristics
• True RS-232 output (Port 2 output not used at time of publication), asynchronous serial input
compatible with RS-232 or TTL voltage levels, RS-232 polarity.
•
User selectable NMEA 0183 baud rate (300, 600, 1200, 2400, 4800, 9600, 19200, 38400). Factory
setting is 4800 baud.
1.5.5.2 Port 1 Protocols
• Configurable between NMEA 0183 Versions 2.00 and 3.00.
•
ASCII output sentences: GPALM, GPGGA, GPGLL, GPGSA, GPGSV, GPRMC, and GPVTG
(NMEA-approved sentences); and PGRMB, PGRME, PGRMF, PGRMM, PGRMT, and PGRMV
(Garmin proprietary sentences).
•
NMEA 0183 Outputs (see section 4.2 for full protocol specifications)
Position, velocity and time
Receiver and satellite status
Differential Reference Station ID and RTCM Data age
Geometry and error estimates
•
NMEA 0183 Inputs (see section 4.1 for full protocol specifications)
Initial position, date and time (not required)
Earth datum and differential mode configuration command, PPS Enable, GPS satellite almanac
•
Configurable for binary data output including GPS carrier phase data
1.5.5.3 Port 2 Protocols
Real-time Differential Correction input (RTCM SC-104 message types 1, 2, 3, 7, and 9)
1.5.5.4 PPS
1 Hz pulse, programmable width, 1 μs accuracy
1.5.6
Antenna Specifications
Should be an active antenna with the following specifications:
Gain:
Antenna should provide between 10 dB to 30 dB net gain between the
antenna feed point and the connection to the GPS 15H & 15L. Consider all
amplifier gains, filter losses, cable losses, etc. when calculating the gain.
RF Connection:
GPS 15H & 15L RF Connection: MCX Female connector (on the GPS
15H & 15L board).
Antenna Connection: MCX Male connector (on the end of the antenna
cable).
Garmin Antenna:
GPS 27C (Garmin Part Number 010-10052-05) provides the required
MCX Male connector. Other Garmin antennas terminated in a BNC Male
connector may also be used if a Garmin MCX to BNC Adapter Cable
(Garmin Part Number 010-10121-00) is used. Place the MCX to BNC
Adapter Cable between the connector on the end of the antenna cable and
the connector on the GPS 15H & 15L.
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GPS 15H & 15L Technical Specifications
Page 6
Rev. D
The total noise figure on the external antenna must be ≤ 7 dB. Refer to the
table below.
Noise Figure/Gain:
18.0
17.0
16.0
SNR (dB)
15.0
14.0
13.0
12.0
11.0
10.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
Gain (dB)
NF=1.3dB
NF=2.3dB
NF=3.3dB
NF=4.3dB
NF=5.3dB
NF=6.3dB
NF=7.3dB
Table 1: Gain vs. SNR for Given Noise Figure
Properly bias the antenna from an on-board source or an external source:
Bias voltage from on-board source: GPS 15H supplies 3.3 VDC to the center conductor of the MCX
female, relative to the connector shell ground.
GPS 15L supplies 3.0 VDC to the center conductor of the MCX
female, relative to the connector shell ground
In both the GPS 15H and 15L, the source resistance of the DC supply to the center conductor of the
connector is approximately 10 Ohms, which is included as a current
limiting resistance. This resistance allows the receiver to survive
momentary shorting of the antenna port.
The GPS 15H and 15L sensors with serial numbers between 27700000
and 28099999 can detect if the antenna is shorted. GPS 15H and 15L
sensors no in the serial number range listed above do not have a
provision to protect against a continuously shorted antenna port.
The antenna must not draw more than 60 mA.
Bias voltage from external source: 4.0 to 8.0 VDC bias through the series combination of an on-board
~10 Ohm current limiting resistance and a Schottky diode.
The antenna must not draw more than 60 mA.
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GPS 15H & 15L Technical Specifications
Page 7
Rev. D
2
GPS 15H & 15L WIRE DESCRIPTIONS AND WIRING DIAGRAMS
The GPS 15H-F & 15L-F use an eight-contact flex circuit LIF (low insertion force) connector. The GPS
15H-W & 15L-W use an eight-pin JST connector (mating wire harness included). See section 1.5.1.3.
2.1
GPS 15H & 15L WIRE DESCRIPTIONS
Pin #
1
Signal Name
BACKUP
POWER
2
3
GROUND
POWER
4
PORT 1
DATA OUT
5
PORT 1
DATA IN
6
RF BIAS
7
PPS
8
PORT 2
DATA IN
190-00266-01
Description
This input provides external power to maintain the real-time clock. This enables
the user to provide backup power if needed for longer than the on-board backup
battery provides (roughly 21 days). Input voltage must be between +2.8 and +3.4
VDC.
Power and Signal Ground
GPS 15L: +3.3 to +5.4 VDC (±100 mV ripple) input. Peak operating current is
100 mA. Nominal operating current is 85 mA. This voltage drives an LDO with a
nominal 3.0 VDC output.
GPS 15H: Unregulated 8.0 to 40 VDC input. Peak operating current is 40 mA @
12 VDC input. Nominal operating current is 33 mA @ 12 VDC input. This
voltage drives a switching regulator with a nominal 3.3 VDC output. Although a
regulated supply is not required, the peak-to-peak voltage ripple on this line
should be kept to less than 100 mV.
Serial Asynchronous Output
RS-232 compatible output normally provides serial data which is formatted per
NMEA 0183, Version 2.0. This output is also capable of outputting phase data
information; see Appendix B: Binary Phase Output Format for details. The
NMEA 0183 baud rate is selectable in the range of 300 to 38400 baud. The default
baud rate is 4800.
First Serial Asynchronous Input
RS-232 compatible with maximum input voltage range of -25 < V < 25. This
input may also be directly connected to standard 3 to 5 VDC CMOS logic that
utilizes RS-232 polarity. The low signal voltage requirement is < 0.6 V, and the
high signal voltage requirement is > 2.4 V. Minimum load impedance is 500 Ω.
This input may be used to receive serial initialization/ configuration data as
specified in section 4.1 Received NMEA 0183 Sentences.
This input allows the user to supply an external RF bias voltage in the range of 4
VDC to 8 VDC to the active antenna. The voltage should be from a clean,
regulated supply and should be well isolated from potential sources of
interference. The supply should not share RF current paths with other system
devices such as microprocessors or other RF circuits. By default, the unit uses an
internal voltage to power the active antenna.
Note: This pin is only operational on units whose serial numbers are higher than
the serial numbers given below:
010-00240-01 GPS 15H-W serial no. 81301857
010-00240-02 GPS 15L-W serial no. 81408976
010-00240-11 GPS 15H-F serial no. 81901632
010-00240-12 GPS 15L-F serial no. 82001471
One-Pulse-Per-Second Output
Typical voltage rise and fall times are 100 ns. Impedance is 250 Ω. The open
circuit output voltage toggles between the low (0 V) and the high (3.3 V for 15H
and 3.0 V for 15L). The default format is a 100 ms wide active-high pulse at a
1 Hz rate, with the pulse width configurable in 20 ms increments. Rising edge is
synchronized to the start of each GPS second. This output provides a nominal 450
mVp-p signal into a 50 Ω load. The pulse time measured at the 50% voltage point
will be approximately 15 ns earlier with a 50 Ω load than with no load.
Second Serial Asynchronous Input
This input may be used to receive serial differential GPS data formatted per
RTCM SC-104 Recommended Standards For Differential Navstar GPS Service,
Version 2.2 (see section 4.5 for more details).
Table 2: GPS 15H & 15L Wire Descriptions
GPS 15H & 15L Technical Specifications
Page 8
Rev. D
2.2
GPS 15H & 15L WIRING DIAGRAMS
Figure 1: Computer Serial Port Interconnection
Figure 2: PDA Serial Port Interconnection
Figure 3: Basic NMEA Device Interconnection
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3
MECHANICAL CHARACTERISTICS & MOUNTING
1. Dimensions in millimeters [inches]
2. Dimension tolerance: +/-0.25 mm [±0.01”]
3. Use M2 mounting screws
Figure 4: GPS 15H-F & 15L-F Dimensions
1. Dimensions identical to GPS 15H-F and GPS 15L-F
2. Use M2 mounting screws
Figure 5: GPS 15H-W & 15L-W Outline Drawing
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4
GPS 15H & 15L SOFTWARE INTERFACE
The GPS 15H & 15L interface protocol design on COM 1 is based on the National Marine Electronics
Association’s NMEA 0183 ASCII interface specification. The COM 2 port can receive differential GPS
(DGPS) correction data using the Radio Technical Commission for Maritime Services’ RTCM SC-104
standard. These standards are fully defined in NMEA 0183, Version 3.0 (copies may be obtained from
NMEA, www.nmea.org) and RTCM Recommended Standards For Differential Navstar GPS Service,
Version 2.2, RTCM Special Committee No.104 (copies may be obtained from RTCM, www.rtcm.org).
The GPS 15H & 15L interface protocol, in addition to transmitting navigation information as defined by
NMEA 0183, transmits additional information using the convention of Garmin proprietary sentences.
These proprietary sentences begin with the characters, “$PGRM”, instead of the characters “$G” that are
typical of the standard NMEA 0183 sentences. The characters “$P” indicate that the sentence is a
proprietary implementation and the characters and the characters “GRM” indicate that it is Garmin’s
proprietary sentence. The letter (or letters) that follow the characters “$PGRM” uniquely identifies that
particular Garmin proprietary sentence.
Binary phase data information can alternatively be output on the COM 1 port; see Appendix B: Binary
Phase Output Format for details.
The following sections describe the NMEA 0183 data format of each sentence transmitted and received by
the GPS 15H & 15L.
4.1
RECEIVED NMEA 0183 SENTENCES
The following paragraphs define the sentences that can be received on the GPS sensor’s port. Null fields in
the configuration sentence indicate no change in the particular configuration parameter. All sentences
received by the GPS sensor must be terminated with <CR><LF>, the ASCII characters for carriage return
(0D hexadecimal) and line feed (0A hexadecimal), respectively. The checksum *hh is used for parity
checking data and is recommended for use in environments containing high electromagnetic noise. It is
generally not required in normal PC environments. When used, the parity bytes (hh) are the ASCII
representation of the upper and lower nibbles of the exclusive-or (XOR) sum of all the characters between
the “$” and “*” characters, non-inclusive. The hex representation must be a capital letter, such as 3D
instead of 3d. Sentences may be truncated by <CR><LF> after any data field and valid fields up to that
point will be acted on by the sensor.
4.1.1
Almanac Information (ALM)
The $GPALM sentence can be used to initialize the GPS sensor’s stored almanac information in the
unlikely event of non-volatile memory loss, or after storage of greater than six months without tracking
GPS satellites.
$GPALM,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
<9>
<10>
<11>
<12>
<13>
<14>
<15>
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Total number of ALM sentences to be transmitted by the GPS sensor during almanac
download. This field can be null or any number when sending almanac to the GPS sensor.
Number of current ALM sentence. This field can be null or any number when sending
almanac to the GPS sensor.
Satellite PRN number, 01 to 32
GPS week number
SV health, bits 17-24 of each almanac page
Eccentricity
Almanac reference time
Inclination angle
Rate of right ascension
Root of semi major axis
Omega, argument of perigee
Longitude of ascension node
Mean anomaly
af0 clock parameter
af1 clock parameter
GPS 15H & 15L Technical Specifications
Page 11
Rev. D
4.1.2
Sensor Initialization Information (PGRMI)
The $PGRMI sentence provides information used to initialize the GPS sensor’s set position and time used
for satellite acquisition. Receipt of this sentence by the GPS sensor causes the software to restart the
satellite acquisition process. If there are no errors in the sentence, it is echoed upon receipt. If an error is
detected, the echoed PGRMI sentence will contain the current default values. Current PGRMI defaults
(with the exception of the Receiver Command, which is a command rather than a mode) can also be
obtained by sending $PGRMIE to the GPS sensor.
$PGRMI,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
4.1.3
Latitude, ddmm.mmm format (leading zeros must be transmitted)
Latitude hemisphere, N or S
Longitude, dddmm.mmm format (leading zeros must be transmitted)
Longitude hemisphere, E or W
Current UTC date, ddmmyy format
Current UTC time, hhmmss format
Receiver Command, A = Auto Locate, R = Unit Reset
Sensor Configuration Information (PGRMC)
The $PGRMC sentence provides information used to configure the GPS sensor’s operation. Configuration
parameters are stored in non-volatile memory and retained between power cycles. The GPS sensor echoes
this sentence upon its receipt if no errors are detected. If an error is detected, the echoed PGRMC sentence
will contain the current default values. Current default values can also be obtained by sending $PGRMCE
to the GPS sensor.
$PGRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>*hh<CR><LF>
<1>
Fix mode, A = automatic, 2 = 2D exclusively (host system must supply altitude),
3 = 3D exclusively
<2>
Altitude above/below mean sea level, -15H & 15L00.0 to 18000.0 meters
<3>
Earth datum index. If the user datum index (96) is specified, fields <4> through <8> must
contain valid values. Otherwise, fields <4> through <8> must be null. Refer to Appendix A:
Earth Datums for a list of earth datums and the corresponding earth datum index.
<4>
User earth datum semi-major axis, 6360000.000 to 6380000.000 meters (.001 meters
resolution)
<5>
User earth datum inverse flattening factor, 285.0 to 310.0 (10-9 resolution)
<6>
User earth datum delta x earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<7>
User earth datum delta y earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<8>
User earth datum delta z earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<9>
Differential mode, A = automatic (output DGPS data when available, non-DGPS otherwise), D
= differential exclusively (output only differential fixes)
<10> NMEA 0183 Baud rate, 1 = 1200, 2 = 2400, 3 = 4800, 4 = 9600, 5 = 19200, 6 = 300, 7 = 600,
8 = 38400
<11> Velocity filter, 0 = No filter, 1 = Automatic filter, 2-255 = Filter time constant (e.g., 10 = 10
second filter)
<12> PPS mode, 1 = No PPS, 2 = 1 Hz
<13> PPS pulse length, 0-48 = (n+1)*20 ms. Example: n = 4 corresponds to a 100 ms wide pulse
<14> Dead reckoning valid time 1-30 (sec)
All configuration changes take effect after receipt of a valid value except baud rate and PPS mode. Baud
rate and PPS mode changes take effect on the next power cycle or an external reset event.
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4.1.4
Additional Sensor Configuration Information (PGRMC1)
The $PGRMC1 sentence provides additional information used to configure the GPS sensor operation.
Configuration parameters are stored in non-volatile memory and retained between power cycles. The GPS
sensor echoes this sentence upon its receipt if no errors are detected. If an error is detected, the echoed
PGRMC1 sentence will contain the current default values. Current default values can also be obtained by
sending $PGRMC1E to the GPS sensor.
$PGRMC1,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
<9>
NMEA 0183 output time 1-900 (sec)
Binary Phase Output Data, 1 = Off, 2 = On
Automatic Position Averaging when Stopped, 1 = Off, 2 = On
DGPS beacon frequency – 0.0, 283.5 – 325.0 kHz in 0.5 kHz steps
DGPS beacon bit rate – 0, 25, 50, 100, or 200 bps
DGPS beacon scanning, 1 = Off, 2 = On
NMEA 0183 version 2.30 mode indicator, 1 = Off, 2 = On
DGPS mode, A = Automatic, W = WAAS Only, R = RTCM Only, N = None (DGPS
disabled)
Power Save Mode, P = Power Save mode, N = Normal
At power up or external reset, a stored beacon frequency other than 0.0 causes the GPS sensor to tune the
beacon receiver. Configuration changes take effect immediately, with the exception of Binary Phase Output
Data, which takes effect on the next power cycle or a reset event. A reset can be commanded by sending
the sentence “$PGRMI,,,,,,,R” (refer to section 4.1.2).
If the GPS sensor is in the Binary data mode, it is necessary to send the following eight-byte data stream to
the COM 1 input to temporarily change the data format to NMEA 0183. Then send a PGRMC1 sentence
that turns off the Binary Phase Output Data format:
10 0A 02 26 00 CE 10 03 (Hexadecimal)
4.1.5
Output Sentence Enable/Disable (PGRMO)
The $PGRMO sentence provides the ability to enable and disable specific output sentences. The following
sentences are enabled at the factory: GPGGA, GPGSA, GPGSV, GPRMC, PGRMB, PGRME, PGRMM,
PGRMT, and PSLIB.
$PGRMO,<1>,<2>*hh<CR><LF>
<1>
<2>
Target sentence description (e.g., PGRMT, GPGSV, etc.)
Target sentence mode, where:
0 = disable specified sentence
1 = enable specified sentence
2 = disable all output sentences (except PSLIB)
3 = enable all output sentences (except GPALM)
4 = restore factory default output sentences
The following notes apply to the PGRMO input sentence:
1.
If the target sentence mode is ‘2’ (disable all), ‘3’ (enable all), or ‘4’ (restore defaults), the target
sentence description is not checked for validity. In this case, an empty field is allowed (e.g.,
$PGRMO,,3), or the mode field may contain from 1 to 5 characters.
2.
If the target sentence mode is ‘0’ (disable) or ‘1’ (enable), the target sentence description field must be
an identifier for one of the sentences that can be output by the GPS sensor.
3.
If either the target sentence mode field or the target sentence description field is not valid, the PGRMO
sentence will have no effect.
4.
$PGRMO,GPALM,1 causes the GPS sensor to transmit all stored almanac information. All other
NMEA 0183 sentence transmission is suspended temporarily.
5.
$PGRMO,,G causes the COM 1 port to change to Garmin Data Transfer format for the duration of the
power cycle. The Garmin mode is required for GPS 15H & 15L product software updates.
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4.1.6
Tune DGPS Beacon Receiver (PSLIB)
The $PSLIB sentence provides the ability to tune a Garmin GBR 21, GBR 23 or equivalent beacon
receiver.
$PSLIB,<1>,<2>*hh<CR><LF>
<1>
Beacon tune frequency, 0.0, 283.5–325.0 kHz in 0.5 kHz steps
<2>
Beacon bit rate, 0, 25, 50, 100, or 200 bps
If valid data is received, the GPS sensor stores it in the EEPROM and echoes the PSLIB command to the
beacon receiver. If the GPS sensor is using any stored beacon frequency other than 0.0, it will tune the
beacon receiver once immediately after power up or external reset.
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4.2
TRANSMITTED NMEA 0183 SENTENCES
The subsequent paragraphs define the sentences that can be transmitted on COM 1 by the GPS sensor.
4.2.1
Sentence Transmission Rate
Sentences are transmitted with respect to the user-selected baud rate.
Regardless of the selected baud rate, the information transmitted by the GPS sensor is referenced to the
one-pulse-per-second output pulse immediately preceding the GPRMC sentence, or whichever sentence is
output first in the burst (see Table 3 below).
The GPS sensor transmits each sentence (except where noted in particular transmitted sentence
descriptions) at a periodic rate based on the user-selected baud rate and user-selected output sentences. The
GPS sensor transmits the selected sentences contiguously. The contiguous transmission starts at a GPS
second boundary. Determine the length of the transmission with the following equation and Tables 3 and 4:
length of transmission =
total characters to be transmitted
--------------------------------------------characters transmitted per second
Sentence
Output by Default?
Maximum Characters
GPRMC
74
GPGGA
82
GPGSA
66
GPGSV
70
PGRME
35
GPGLL
44
GPVTG
42
PGRMV
32
PGRMF
82
PGRMB
40
PGRMM
32
PGRMT
Once per minute
50
Table 3: NMEA 0183 Output Sentence Order and Size
Baud
Characters per Second
300
30
600
60
1200
120
2400
240
4800
480
9600
960
19200
1920
38400
3840
Table 4: Characters per Second for Available Baud Rates
The maximum number of fields allowed in a single sentence is 82 characters including delimiters. Values
in the table include the sentence start delimiter character “$” and the termination delimiter <CR><LF>. The
factory set defaults result in a once per second transmission at the NMEA 0183 specification transmission
rate of 4800 baud.
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4.2.2
Transmitted Time
The GPS sensor outputs UTC (Coordinated Universal Time) date and time of day in the transmitted
sentences. Before the initial position fix, the on-board clock provides the date and time of day. After the
initial position fix, the date and time of day are calculated using GPS satellite information and are
synchronized with the one-pulse-per-second output.
The GPS sensor uses information obtained from the GPS satellites to add or delete UTC leap seconds and
correct the transmitted date and time of day. The transmitted date and time of day for leap second
correction follow the guidelines in National Institute of Standards and Technology Special Publication 432
(Revised 1990). This document is for sale by the Superintendent of Documents, U.S. Government Printing
Office, Washington, D.C., 20402, U.S.A.
When a positive leap second is required, one second is inserted at the beginning of the first hour (0h 0m 0s)
of the day that the positive leap is occurring. The minute containing the leap second is 61 seconds long. The
GPS sensor would have transmitted this information for the leap second added December 31, 1998 as
follows:
$GPRMC,235959,A,3851.3651,N,09447.9382,W,000.0,221.9,071103,003.3,E*69
$GPRMC,000000,A,3851.3651,N,09447.9382,W,000.0,221.9,081103,003.3,E*67
$GPRMC,000000,A,3851.3651,N,09447.9382,W,000.0,221.9,081103,003.3,E*67
$GPRMC,000001,A,3851.3651,N,09447.9382,W,000.0,221.9,081103,003.3,E*66
If a negative leap second should be required, one second is deleted at the end of some UTC month. The
minute containing the leap second will be only 59 seconds long. In this case, the GPS sensor will not
transmit the time of day 0h 0m 0s (the “zero” second) for the day from which the leap second is removed.
$GPRMC,235959,A,3851.3650,N,09447.9373,W,000.0,000.0,111103,003.3,E*69
$GPRMC,000001,A,3851.3650,N,09447.9373,W,000.0,000.0,121103,003.3,E*6A
$GPRMC,000002,A,3851.3650,N,09447.9373,W,000.0,000.0,121103,003.3,E*69
4.2.3
Global Positioning System Almanac Data (ALM)
Almanac sentences are not normally transmitted. Almanac transmission can be initiated by sending the
GPS sensor a $PGRMO,GPALM,1 command. Upon receipt of this command, the GPS sensor transmits
available almanac information on GPALM sentences. During the transmission of almanac sentences, other
NMEA 0183 data output is suspended temporarily.
$GPALM,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>*hh<CR><LF>
<field information> can be found in section 4.1.1.
4.2.4
Global Positioning System Fix Data (GGA)
$GPGGA,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,M,<10>,M,<11>,<12>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
<9>
<10>
<11>
<12>
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UTC time of position fix, hhmmss format
Latitude, ddmm.mmmm format (leading zeros are transmitted)
Latitude hemisphere, N or S
Longitude, dddmm.mmmm format (leading zeros are transmitted)
Longitude hemisphere, E or W
GPS quality indication, 0 = fix not available, 1 = Non-differential GPS fix available, 2 =
differential GPS fix available, 6 = estimated (only if NMEA 0183 version 2.30 mode is enabled
in field 7 of the PGRMC1 sentence; see section 4.1.4.)
Number of satellites in use, 00 to 12 (leading zeros are transmitted)
Horizontal dilution of precision, 0.5 to 99.9
Antenna height above/below mean sea level, -9999.9 to 99999.9 meters
Geoidal height, -999.9 to 9999.9 meters
Differential GPS (RTCM SC-104) data age, number of seconds since last valid RTCM
transmission (null if not an RTCM DGPS fix)
Differential Reference Station ID, 0000 to 1023 (leading zeros are transmitted, null if not an
RTCM DGPS fix)
GPS 15H & 15L Technical Specifications
Page 16
Rev. D
4.2.5
GPS DOP and Active Satellites (GSA)
$GPGSA,<1>,<2>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<4>,<5>,<6>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
4.2.6
Mode, M = manual, A = automatic
Fix type, 1 = not available, 2 = 2D, 3 = 3D
PRN number, 01 to 32, of satellite used in solution, up to 12 transmitted (leading zeros are
transmitted)
Position dilution of precision, 0.5 to 99.9
Horizontal dilution of precision, 0.5 to 99.9
Vertical dilution of precision, 0.5 to 99.9
GPS Satellites in View (GSV)
$GPGSV,<1>,<2>,<3>,<4>,<5>,<6>,<7>,...<4>,<5>,<6>,<7>*hh<CR><LF>
<1>
Total number of GSV sentences to be transmitted
<2>
Number of current GSV sentence
<3>
Total number of satellites in view, 00 to 12 (leading zeros are transmitted)
<4>
Satellite PRN number, 01 to 32 (leading zeros are transmitted)
<5>
Satellite elevation, 00 to 90 degrees (leading zeros are transmitted)
<6>
Satellite azimuth, 000 to 359 degrees, true (leading zeros are transmitted)
<7>
Signal to noise ratio (C/No) 00 to 99 dB, null when not tracking (leading zeros are transmitted)
Note: Items <4>,<5>,<6>, and <7> repeat for each satellite in view to a maximum of four (4) satellites per
sentence. Additional satellites in view information must be sent in subsequent bursts of NMEA 0183 data.
These fields will be null if unused.
4.2.7
Recommended Minimum Specific GPS/TRANSIT Data (RMC)
$GPRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
<9>
<10>
<11>
<12>
4.2.8
UTC time of position fix, hhmmss format
Status, A = Valid position, V = NAV receiver warning
Latitude, ddmm.mmmm format (leading zeros are transmitted)
Latitude hemisphere, N or S
Longitude, dddmm.mmmm format (leading zeros are transmitted)
Longitude hemisphere, E or W
Speed over ground, 000.0 to 999.9 knots (leading zeros are transmitted)
Course over ground, 000.0 to 359.9 degrees, true (leading zeros are transmitted)
UTC date of position fix, ddmmyy format
Magnetic variation, 000.0 to 180.0 degrees (leading zeros are transmitted)
Magnetic variation direction, E or W (westerly variation adds to true course)
Mode indicator (only output if NMEA 0183 version 2.30 active), A = Autonomous, D =
Differential, E = Estimated, N = Data not valid
Track Made Good and Ground Speed (VTG)
$GPVTG,<1>,T,<2>,M,<3>,N,<4>,K,<5>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
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True course over ground, 000 to 359 degrees (leading zeros are transmitted)
Magnetic course over ground, 000 to 359 degrees (leading zeros are transmitted)
Speed over ground, 000.0 to 999.9 knots (leading zeros are transmitted)
Speed over ground, 0000.0 to 1851.8 kilometers per hour (leading zeros are transmitted)
Mode indicator (only output if NMEA 0183 version 3.00 active), A = Autonomous,
D = Differential, E = Estimated, N = Data not valid
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Rev. D
4.2.9
Geographic Position (GLL)
$GPGLL,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
Latitude, ddmm.mmmm format (leading zeros are transmitted)
Latitude hemisphere, N or S
Longitude, dddmm.mmmm format (leading zeros are transmitted)
Longitude hemisphere, E or W
UTC time of position fix, hhmmss format
Status, A = Valid position, V = NAV receiver warning
Mode indicator (only output if NMEA 0183 version 3.00 active), A = Autonomous,
D = Differential, E = Estimated, N = Data not valid
4.2.10 Estimated Error Information (PGRME)
$PGRME,<1>,M,<2>,M,<3>,M*hh<CR><LF>
<1>
<2>
<3>
Estimated horizontal position error (HPE), 0.0 to 999.9 meters
Estimated vertical position error (VPE), 0.0 to 999.9 meters
Estimated position error (EPE), 0.0 to 999.9 meters
4.2.11 GPS Fix Data Sentence (PGRMF)
$PGRMF,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
<9>
<10>
<11>
<12>
<13>
<14>
<15>
GPS week number (0 - 1023)
GPS seconds (0 - 604799)
UTC date of position fix, ddmmyy format
UTC time of position fix, hhmmss format
GPS leap second count
Latitude, ddmm.mmmm format (leading zeros are transmitted)
Latitude hemisphere, N or S
Longitude, dddmm.mmmm format (leading zeros are transmitted)
Longitude hemisphere, E or W
Mode, M = manual, A = automatic
Fix type, 0 = no fix, 1 = 2D fix, 2 = 3D fix
Speed over ground, 0 to 1851 kilometers/hour
Course over ground, 0 to 359 degrees, true
Position dilution of precision, 0 to 9 (rounded to nearest integer value)
Time dilution of precision, 0 to 9 (rounded to nearest integer value)
4.2.12 Map Datum (PGRMM)
The Garmin Proprietary sentence $PGRMM gives the name of the map datum currently in use by the GPS
sensor. This information is used by the Garmin MapSource® real-time plotting application.
$PGRMM,<1>*hh<CR><LF>
<1>
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Name of map datum currently in use (variable length field, e.g., “WGS 84”)
GPS 15H & 15L Technical Specifications
Page 18
Rev. D
4.2.13 Sensor Status Information (PGRMT)
The Garmin Proprietary sentence $PGRMT gives information concerning the status of the GPS sensor.
This sentence is transmitted once per minute regardless of the selected baud rate.
$PGRMT,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
<9>
<10>
Product, model and software version (variable length field, e.g., “GPS 15H & 15L VER
2.05”)
ROM checksum test, P = pass, F = fail
Receiver failure discrete, P = pass, F = fail
Stored data lost, R = retained, L = lost
Real time clock lost, R = retained, L = lost
Oscillator drift discrete, P = pass, F = excessive drift detected
Data collection discrete, C = collecting, null if not collecting
GPS sensor temperature. Use for a reference only, but could be null
GPS sensor configuration data, R = retained, L = lost
P = pass (Antenna is NOT shorted), F = fail (Antenna is shorted)
Note: This field is only available on units whose serial numbers are in the range listed
below:
010-00240-01 GPS 15H-W serial number between 27700000 through 27799999
010-00240-02 GPS 15L-W serial number between 27800000 through 27899999
010-00240-11 GPS 15H-F serial number between 27900000 through 27999999
010-00240-12 GPS 15L-F serial number between 28000000 through 28099999
4.2.14 3D velocity Information (PGRMV)
$PGRMV,<1>,<2>,<3>*hh<CR><LF>
<1>
<2>
<3>
True east velocity, -514.4 to 514.4 meters/second
True north velocity, -514.4 to 514.4 meters/second
Up velocity, -999.9 to 9999.9 meters/second
4.2.15 DGPS Beacon Information (PGRMB)
$PGRMB,<1>,<2>,<3>,<4>,<5>,K,<6>,<7>*hh<CR><LF>
<1>
<2>
<3>
<4>
<5>
<6>
<7>
<8>
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Beacon tune frequency, 0.0, 283.5–325.0 kHz in 0.5 kHz steps
Beacon bit rate, 0, 25, 50, 100, or 200 bps
Beacon SNR, 0 to 31
Beacon data quality, 0 to 100
Distance to beacon reference station in kilometers
Beacon receiver communication status (0 = Check Wiring, 1 = No Signal, 2 = Tuning, 3 =
Receiving, 4= Scanning)
DGPS fix source (R = RTCM, W = WAAS, N = Non-DGPS Fix)
DGPS mode, A = Automatic, W = WAAS Only, R = RTCM Only, N = None (DGPS
disabled)
GPS 15H & 15L Technical Specifications
Page 19
Rev. D
4.3
BAUD RATE SELECTION
Baud rate selection can be performed by sending the appropriate configuration sentence to the GPS sensor
as described in the $PGRMC section 4.1.3, field <10>.
4.4
ONE-PULSE-PER-SECOND (PPS) OUTPUT
The highly accurate one-pulse-per-second (PPS) output is provided for applications requiring precise
timing measurements. The signal is generated after the initial position fix has been calculated and continues
until power down. The rising edge of the signal is synchronized to the start of each GPS second.
Regardless of the selected baud rate, the information transmitted by the GPS 15H & 15L is referenced to
the pulse immediately preceding the NMEA 0183 RMC sentence.
The accuracy of the one-pulse-per-second output is maintained only while the GPS 15H & 15L can
compute a valid position fix. To obtain the most accurate results, the one-pulse-per-second output should be
calibrated against a local time reference to compensate for cable and internal receiver delays and the local
time bias.
The default pulse width is 100 ms, however; it may be programmed in 20 ms increments between 20 ms
and 980 ms as described in $PGRMC section 4.1.3, field <13>.
4.5
RECEIVED RTCM DATA
Position accuracy of less than 5 meters can be achieved with the GPS 15H & 15L by using Differential
GPS (DGPS) real-time pseudo-range correction data in RTCM SC-104 format, with message types 1, 2, 3,
7, and 9. These corrections can be received by the GPS 15H & 15L on COM 2. The RTCM data must be
received at the same baud rate as the COM 1 port. For details on the SC-104 format, refer to RTCM Paper
134-89/SC 104-68 by the Radio Technical Commission for Maritime Services.
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GPS 15H & 15L Technical Specifications
Page 20
Rev. D
APPENDIX A: EARTH DATUMS
The following is a list of the Garmin GPS 15H & 15L Earth datum indices and the corresponding earth
datum name (including the area of application):
0
ADINDAN - Ethiopia, Mali, Senegal, Sudan
1
AFGOOYE - Somalia
2
AIN EL ABD 1970 - Bahrain Island, Saudi Arabia
3
ANNA 1 ASTRO 1965 - Cocos Island
4
ARC 1950 - Botswana, Lesotho, Malawi, Swaziland, Zaire, Zambia, Zimbabwe
5
ARC 1960 - Kenya, Tanzania
6
ASCENSION ISLAND 1958 - Ascension Island
7
ASTRO BEACON “E” - Iwo Jima Island
8
AUSTRALIAN GEODETIC 1966 - Australia, Tasmania Island
9
AUSTRALIAN GEODETIC 1984 - Australia, Tasmania Island
10
ASTRO DOS 71/4 - St. Helena Island
11
ASTRONOMIC STATION 1952 - Marcus Island
12
ASTRO B4 SOROL ATOLL - Tern Island
13
BELLEVUE (IGN) - Efate and Erromango Islands
14
BERMUDA 1957 - Bermuda Islands
15
BOGOTA OBSERVATORY - Colombia
16
CAMPO INCHAUSPE - Argentina
17
CANTON ASTRO 1966 - Phoenix Islands
18
CAPE CANAVERAL - Florida, Bahama Islands
19
CAPE - South Africa
20
CARTHAGE - Tunisia
21
CHATHAM 1971 - Chatham Island (New Zealand)
22
CHUA ASTRO - Paraguay
23
CORREGO ALEGRE - Brazil
24
DJAKARTA (BATAVIA) - Sumatra Island (Indonesia)
25
DOS 1968 - Gizo Island (New Georgia Islands)
26
EASTER ISLAND 1967 - Easter Island
27
EUROPEAN 1950 - Austria, Belgium, Denmark, Finland, France, Germany, Gibraltar, Greece,
Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland
28
EUROPEAN 1979 - Austria, Finland, Netherlands, Norway, Spain, Sweden, Switzerland
29
FINLAND HAYFORD 1910 - Finland
30
GANDAJIKA BASE - Republic of Maldives
31
GEODETIC DATUM 1949 - New Zealand
32
ORDNANCE SURVEY OF GREAT BRITAIN 1936 - England, Isle of Man, Scotland,
Shetland Islands, Wales
33
GUAM 1963 - Guam Island
34
GUX 1 ASTRO - Guadalcanal Island
35
HJORSEY 1955 - Iceland
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GPS 15H & 15L Technical Specifications
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Rev. D
36
HONG KONG 1963 - Hong Kong
37
INDIAN - Bangladesh, India, Nepal
38
INDIAN - Thailand, Vietnam
39
IRELAND 1965 - Ireland
40
ISTS O73 ASTRO 1969 - Diego Garcia
41
JOHNSTON ISLAND 1961 - Johnston Island
42
KANDAWALA - Sri Lanka
43
KERGUELEN ISLAND - Kerguelen Island
44
KERTAU 1948 - West Malaysia, Singapore
45
L.C. 5 ASTRO - Cayman Brac Island
46
LIBERIA 1964 - Liberia
47
LUZON - Mindanao Island
48
LUZON - Phillippines (excluding Mindanao Island)
49
MAHE 1971 - Mahe Island
50
MARCO ASTRO - Salvage Islands
51
MASSAWA - Eritrea (Ethiopia)
52
MERCHICH - Morocco
53
MIDWAY ASTRO 1961 - Midway Island
54
MINNA - Nigeria
55
NORTH AMERICAN 1927 - Alaska
56
NORTH AMERICAN 1927 - Bahamas (excluding San Salvador Island)
57
NORTH AMERICAN 1927 - Central America (Belize, Costa Rica, El Salvador, Guatemala,
Honduras, Nicaragua)
58
NORTH AMERICAN 1927 - Canal Zone
59
NORTH AMERICAN 1927 - Canada (including Newfoundland Island)
60
NORTH AMERICAN 1927 - Caribbean (Barbados, Caicos Islands, Cuba, Dominican
Republic, Grand Cayman, Jamaica, Leeward Islands, Turks Islands)
61
NORTH AMERICAN 1927 - Mean Value (CONUS)
62
NORTH AMERICAN 1927 - Cuba
63
NORTH AMERICAN 1927 - Greenland (Hayes Peninsula)
64
NORTH AMERICAN 1927 - Mexico
65
NORTH AMERICAN 1927 - San Salvador Island
66
NORTH AMERICAN 1983 - Alaska, Canada, Central America, CONUS, Mexico
67
NAPARIMA, BWI - Trinidad and Tobago
68
NAHRWAN - Masirah Island (Oman)
69
NAHRWAN - Saudi Arabia
70
NAHRWAN - United Arab Emirates
71
OBSERVATORIO 1966 - Corvo and Flores Islands (Azores)
72
OLD EGYPTIAN - Egypt
73
OLD HAWAIIAN - Mean Value
74
OMAN - Oman
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Rev. D
75
PICO DE LAS NIEVES - Canary Islands
76
PITCAIRN ASTRO 1967 - Pitcairn Island
77
PUERTO RICO - Puerto Rico, Virgin Islands
78
QATAR NATIONAL - Qatar
79
QORNOQ - South Greenland
80
REUNION - Mascarene Island
81
ROME 1940 - Sardinia Island
82
RT 90 - Sweden
83
PROVISIONAL SOUTH AMERICAN 1956 - Bolivia, Chile, Colombia, Ecuador, Guyana,
Peru, Venezuela
84
SOUTH AMERICAN 1969 - Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana,
Paraguay, Peru, Venezuela, Trinidad and Tobago
85
SOUTH ASIA - Singapore
86
PROVISIONAL SOUTH CHILEAN 1963 - South Chile
87
SANTO (DOS) - Espirito Santo Island
88
SAO BRAZ - Sao Miguel, Santa Maria Islands (Azores)
89
SAPPER HILL 1943 - East Falkland Island
90
SCHWARZECK - Namibia
91
SOUTHEAST BASE - Porto Santo and Madeira Islands
92
SOUTHWEST BASE - Faial, Graciosa, Pico, Sao Jorge, and Terceira Islands (Azores)
93
TIMBALAI 1948 - Brunei and East Malaysia (Sarawak and Sabah)
94
TOKYO - Japan, Korea, Okinawa
95
TRISTAN ASTRO 1968 - Tristan da Cunha
96
User defined earth datum
97
VITI LEVU 1916 - Viti Levu Island (Fiji Islands)
98
WAKE-ENIWETOK 1960 - Marshall Islands
99
WORLD GEODETIC SYSTEM 1972
100
WORLD GEODETIC SYSTEM 1984
101
ZANDERIJ - Surinam
102
CH-1903 - Switzerland
103
Hu - Tzu - Shan
104
Indonesia 74
105
Austria
106
Potsdam
107
Taiwan - modified Hu-Tzu-Shan
108
GDA - Geocentric Datum of Australia
109
Dutch
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Rev. D
APPENDIX B: BINARY PHASE OUTPUT FORMAT
In binary phase output mode, GPS 15H & 15L series products transmit two types of packets once per
second. One record contains primarily post-process information such as position and velocity information.
The second record contains receiver measurement information. For the GPS 15H & 15L, the records are
sent at a default baud rate of 9600 baud, 8 data bits, and no parity.
To turn these records on, use the $PGRMC1 NMEA sentence as described in section 4 GPS 15H & 15L
Software Interface. (Refer to the Garmin GPS Interface Specification for details on how to form and parse
Garmin packets. At the time of this printing, these specs are available from the technical support section of
our Web site: http://www.garmin.com/support/commProtocol.html.)
Note: The satellite data information is also enabled when the position record is enabled.
Records sent over RS232 begin with a delimiter byte (10 hex). The second byte identifies the record type
(33 hex for a position record and 34 hex for a receiver measurement). The third byte indicates the size of
the data. The fourth byte is the first byte of data. The data is then followed by a checksum byte, a delimiter
byte (10 hex), and an end-of-transmission character (03 hex). Additionally, any DLEs (0x10) that appear
between the delimeters are escaped with a second DLE. Refer to the end of this section for sample code
that strips off the DLEs and ETXs.
RS232 Packet:
- 0x10
(DLE is first byte)
- 0x##
(Record ID – single byte)
- 0x##
(Number of data bytes – single byte)
- data bytes
(See descriptions below)
- 0x##
(2’s complement of the arithmetic sum of the bytes between the delimiters)
- 0x10
(DLE)
- 0x03
(ETX is last byte)
The data bytes of each packet contain the record specified by the record ID. A description of each record
follows.
Satellite Data Record
The satellite data has a record ID of 0x72 with 84 (0x54) data bytes. The data bytes contain the data for the
12 channels as described below. For each satellite, the following data is available:
typedef
struct
{
uint8
svid;
//space vehicle identification (1–32 and 33–64 for WAAS)
uint16
snr;
//signal-to-noise ratio
uint8
elev;
//satellite elevation in degrees
uint16
azmth;
//satellite azimuth in degrees
uint8
status;
//status bit-field
} cpo_sat_data;
190-00266-01
GPS 15H & 15L Technical Specifications
Page 24
Rev. D
The status bit field represents a set of booleans described below:
Bit
Meaning when bit is one (1)
0
The unit has ephemeris data for the specified satellite.
1
The unit has a differential correction for the specified satellite.
2
The unit is using this satellite in the solution.
This pattern is repeated for all 12 channels for a total of 12 X 7 bytes = 84 (0x54) bytes :
typedef
struct
{
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
cpo_sat_data
} cpo_all_sat_data
The RS-232 Packet for the Satellite Record looks like:
- 0x10
(DLE is first byte)
- 0x72
(Record ID – single byte)
- 0x54
(Number of data bytes – single byte)
- cpo_all_sat_data
- 0x##
(2’s complement of the arithmetic sum of the bytes between the delimiters)
- 0x10
(DLE)
- 0x03
(ETX is last byte)
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GPS 15H & 15L Technical Specifications
Page 25
Rev. D
Position Record
The Position Record has a record identifier of
typedef struct
{
float
alt;
float
epe;
float
eph;
float
epv;
int
fix;
double
gps_tow;
double
lat;
double
lon;
float
lon_vel;
float
lat_vel;
float
alt_vel;
float
msl_hght;
int
leap_sec;
long
grmn_days;
} cpo_pvt_data;
alt
epe
eph
epv
fix
gps_tow
lat
lon
lon_vel
lat_vel
alt_vel
msl_hght
leap_sec
grmn_days
Ellipsoid altitude (meters)
Est pos error (meters)
Pos err, horizontal (meters)
Pos err, vertical (meters)
0 = no fix; 1 = no fix; 2 = 2D; 3 = 3D; 4 = 2D differential; 5 = 3D differential;
6 and greater - not defined
GPS time of week (sec)
Latitude (radians)
Longitude (radians)
Longitude velocity (meters/second)
Latitude velocity (meters/second)
Altitude velocity (meters/second)
Mean sea level height (meters)
UTC leap seconds
Garmin days (days since December 31, 1989)
Receiver Measurement Record
typedef struct
{
unsigned long
double
unsigned int
char
unsigned char
char
char
} cpo_rcv_sv_data;
typedef struct
{
double
int
cpo_rcv_sv_data
} cpo_rcv_data;
rcvr_tow
rcvr_wn
cycles
pr
phase
slp_dtct
snr_dbhz
190-00266-01
cycles;
pr;
phase;
slp_dtct;
snr_dbhz;
svid;
valid;
rcvr_tow;
rcvr_wn;
sv[ 12 ];
Receiver time of week (seconds)
Receiver week number
Number of accumulated cycles
Pseudorange (meters)
To convert to (0 -359.999) multiply by 360.0 and divide by 2048.0
0 = no cycle slip detected; non-zero = cycle slip detected
Signal strength - db Hz
GPS 15H & 15L Technical Specifications
Page 26
Rev. D
svid
valid
Satellite number (0-31 and 119-138 for WAAS) Note: Add 1 to offset to current svid
numbers.
0 = information not valid; non-zero = information valid
Sample C Code
DLE and ETX bytes:
Sample C code to receive the two records should filter DLE and ETX bytes as described below:
typedef enum
{
DAT,
DLE,
ETX
} rx_state_type;
/* Declare and initialize static variables */
static char
in_que[ 256 ];
static int
in_que_ptr = 0;
static rx_state_type rx_state = DAT;
.
.
.
void add_to_que( char data )
{
#define DLE_BYTE 0x10
#define ETX_BYTE 0x03
if ( rx_state == DAT )
{
if ( data == DLE_BYTE )
{
rx_state = DLE;
}
else
{
in_que[ in_que_ptr++ ] = data;
}
}
else if ( rx_state == DLE )
{
if ( data == ETX_BYTE )
{
rx_state = ETX;
}
else
{
rx_state = DAT;
in_que[ in_que_ptr++ ] = data;
}
}
else if ( rx_state == ETX )
{
if ( data == DLE_BYTE )
{
rx_state = DLE;
}
}
if ( in_que_ptr > 255 )
{
in_que_ptr = 0;
}
}
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Page 27
Rev. D
APPENDIX C: CHANGING THE BAUD RATE IN GARMIN MODE
In certain cases, you may need to change the default baud rate of your Garmin GPS receiver while in
Garmin mode. Follow these steps to temporarily change the baud rate.
Refer to the Garmin Device Interface Specification for details on how to form and parse Garmin packets.
At the time of this printing, these specs are available from the technical suppport section of our Web site:
http://www.garmin.com/support/commProtocol.html.
1.
Turn off all requests by transmitting packet:
id = IOP_RQST_DATA (0x1C)
data = 0 (16-bit unsigned integer )
2.
The GPS unit will respond by sending a packet with id = IOP_ACK_BYTE (0x06)
3.
After you receive the above packet, transmit packet:
id = IOP_BAUD_RQST_DATA (0x30)
data = baud rate to change to (32-bit unsigned integer; for example, 38400)
4.
The GPS unit will respond by sending a packet:
id = IOP_BAUD_ACPT_DATA (0x31)
data = highest acceptable baud rate closest to what was requested
(32-bit unsigned integer; for example, 38361 decimal)
5.
Determine the actual baud rate value from the data sent in step 4. This value will be within +/- 5% of
the actual baud rate. (For example, the GPS unit might send a baud rate of 38361, which correlates to a
baud rate of 38400).
6.
If the baud rate in step 5 is acceptable, transmit packet:
id = IOP_ACK_BYTE (0x06)
data = IOP_BAUD_ACPT_DATA (0x31)
7.
Sleep for a small amount of time, about 100 milliseconds, to make sure the packet in (6) was
successfully transmitted to the GPS unit.
8.
Close the current connection to the GPS unit and immediately open a new connection with the new
baud rate obtained in step 5.
9.
Immediately after establishing a connection, transmit packet:
id = IOP_CMND_DATA (0x0A)
data = IOP_ACK_PING (0x3A)
10. The GPS will respond by sending a packet:
id = IOP_ACK_BYTE (0x06)
data = IOP_CMND_DATA (0x0A)
11. After you receive the above packet, transmit the same packet in step 9 again.
id = IOP_CMND_DATA (0x0A)
data = IOP_ACK_PING (0x3A)
12. The GPS will respond again with the same packet in step 10.
id = IOP_ACK_BYTE (0x06)
data = IOP_CMND_DATA (0x0A)
13. The baud rate has been successfully changed upon receiving the above packet. If the GPS unit does
not receive these two IOP_CMND_DATA packets within two seconds, it will reset its baud rate to
9600.
190-00266-01
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Page 28
Rev. D
APPENDIX D: EPHEMERIS DATA DOWNLOAD (PROGRAMMING EXAMPLE)
Synopsis
This section describes, using an example, how to download ephemeris information from a Garmin 15, 16,
17 or 18 family GPS unit with the exception of the GPS 15-W and the GPS 15-F.
Garmin Binary Format Review
In order to download the ephemeris data, you must first command the unit to output information in Garmin
Binary Format (Garmin mode) instead of the default NMEA output format. To put the unit in Garmin
mode, connect to the unit using a terminal program and send the following NMEA sentence:
$PGRMO,,G*hh<CR><LF>
The checksum *hh is used for parity checking data and is not required, but is recommended for use in
environments containing high electromagnetic noise. It is generally not required in normal PC
environments. When used, the parity bytes (hh) are the ASCII representation of the exclusive-or (XOR)
sum of all the characters between the "$” and “*” characters, non-inclusive. Sentences may be truncated by
<CR><LF> after any data field and valid fields up to that point are acted on by the GPS sensor. The unit
stays in Garmin mode until the next power cycle.
Now that unit is in Garmin binary format, transmitted and received packets are structured as follows:
Byte Description
Packet Delimiter
Packet ID (type)
Data Size
Name
DLE
ID
SIZE
Data bytes
.
.
.
Checksum
DATA
Packet Delimiter
End of Packet
CHKSUM
Notes
0x10
Packet type
Number of bytes in data portion(not
including escaped DLEs. See below)
Not to exceed 256 bytes
.
.
.
.
.
.
2’s complement of the arithmetic
sum of all the bytes from the
Packet ID byte to the last DATA
byte(inclusive) not counting
escaped DLEs. See below
DLE
0x10
ETX
0x03
The DLE (0x10) is a delimiter byte used in conjunction with the ETX byte to determine beginning and
ending of a packet. However, a 0x10 could appear in the data itself, so if this occurs the byte is escaped
with another DLE byte (sometimes referred to as DLE stuffing). In other words, if a DLE occurs in the
data, another DLE is transmitted immediately after to indicate that it is a data byte and it is not being used
as a delimiter. Note that the size byte of the packet does not count the second DLE byte in an escaped DLE
pair in the data field. Since a DLE that is a part of the data will have a second DLE to escape it, a single
DLE followed by an ETX byte means that the end of a packet has been reached.
In order to interpret these packets properly, one must remove the escaped DLE bytes. This can be achieved
using an algorithm similar to the Sample C Code fragment on the previous page.
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GPS 15H & 15L Technical Specifications
Page 29
Rev. D
Ephemeris Download Procedure
The following is the sequence of events that occurs when downloading ephemeris data.
Send a packet containing the command that requests ephemeris data (IOP_DOWN_LOAD_EPH). The
packet should look like this:
TX Packet: Ephemeris Data Request
Byte Description
Name
HEX Value
Delimiter
DLE
0x10
Command Data ID
IOP_CMND_DATA
0x0A
Number of bytes in data
SIZE
0x02
Request to D/L ephemeris
IOP_DOWN_LOAD_EPH
0x5D
Pad to 2 bytes
DATA
0x00
Checksum calculation
CHKSUM
0x97*
Delimiter
DLE
0x10
End
ETX
0x03
* From now on, checksum calculation will not be shown for every packet example
The unit returns an acknowledgement packet that looks like this:
RX Packet: Acknowledgement
Byte Description
Delimiter
Acknowledgement ID
Number of bytes in data
Request to D/L ephemeris
Pad
Checksum calculation
Delimiter
End of packet
Name
DLE
IOP_ACK_BYTE
SIZE
IOP_CMND_DATA
DATA
CHKSUM
DLE
ETX
HEX Value
0x10
0x06
0x02
0x0A
0x00
---0x10
0x03
Then, the unit immediately sends a packet communicating how many data packets to expect for the
ephemeris download (a maximum of twelve):
RX Packet: Number of Data Packets to Expect
Byte Description
Delimiter
Record ID
Number of bytes in data
Number of records
Pad
Checksum calculation
Delimiter
End of packet
Name
DLE
IOP_RECORDS
SIZE
NUM_SV
DATA
CHKSUM
DLE
ETX
HEX Value
0x10
0x1B
0x02
0x0C
0x00
---0x10
0x03
This packet requires acknowledgement, as shown below (note that the data field contains the
IOP_RECORDS ID to indicate the acknowledgement of the IOP_RECORDS packet):
TX Packet: Acknowledgement
Byte Description
Delimiter
Record ID
Number of bytes in data
Pad
ID of packet being ACK’d
Checksum calculation
Delimiter
End of packet
190-00266-01
Name
DLE
IOP_ACK_BYTE
SIZE
DATA
IOP_RECORDS
CHKSUM
DLE
ETX
GPS 15H & 15L Technical Specifications
Page 30
HEX Value
0x10
0x06
0x02
0x00
0x1B
---0x10
0x03
Rev. D
Next, the unit sends the specified number of packets containing the ephemeris information. An example
packet is shown below. Each packet should be acknowledged as before (be sure to modify the ACK packet
to indicate what type of packet being acknowledged—for ephemeris data the ID is 0x35).
RX Packet: Ephemeris Data
Byte Description
Delimiter
Ephemeris data ID
Number of bytes in data
Ephemeris data
.
.
.
Checksum calculation
Delimiter
End of packet
Name
DLE
IOP_SPC_EPH_DATA
SIZE
DATA
.
.
.
CHKSUM
DLE
ETX
HEX Value
0x10
0x35
0x78
---.
.
.
---0x10
0x03
The data portion of each packet can then be parsed into an instance of the following structure. Each of these
structures represents data from a single satellite.
typedef struct
{
sint16 wn;
float
toc;
float
toe;
float
af0;
float
af1;
float
af2;
float
ura;
double e;
double sqrta;
double dn;
double m0;
double w;
double omg0;
double i0;
float
odot;
float
idot;
float
cus;
float
cuc;
float
cis;
float
cic;
float
crs;
float
crc;
unsigned char iod;
} SDM_spc_eph_type;
190-00266-01
/* ephemeris data record for SPC
*/
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
week number (weeks)
reference time of clock parameters (s)
reference time of ephemeris parameters (s)
clock correction coefficient - group delay
(s)
clock correction coefficient
(s/s)
clock correction coefficient
(s/s/s)
user range accuracy
(m)
eccentricity
(-)
square root of semi-major axis (a) (m**1/2)
mean motion correction
(r/s)
mean anomaly at reference time
(r)
argument of perigee
(r)
right ascension
(r)
inclination angle at reference time
(r)
rate of right ascension
(r/s)
rate of inclination angle
(r/s)
argument of latitude correction, sine
(r)
argument of latitude correction, cosine (r)
inclination correction, sine
(r)
inclination correction, cosine
(r)
radius correction, sine
(m)
radius correction, cosine
(m)
issue of data
GPS 15H & 15L Technical Specifications
Page 31
Rev. D
An example function to complete the parsing is shown below. Note that the double data types are converted
by the function cnvt_ieee_double(). This function merely swaps the upper and lower words of the
double. This is necessary on GPS 15, 16, 17 series sensors due to a compatibility issue with the IEEE
floating point standard): In this example, the array m_TempArray contains the data portion of the
ephemeris packet (with DLE stuffing removed).
/****************************************************************************
*
*
PROCEDURE NAME:
*
copyData - ephemeris data unpacker
*
*
DESCRIPTION:
*
unpacks data from ephemeris packet DATA field after extraneous DLEs
*
have been removed. Note that sint16 refers to a signed 16-bit
*
integer type.
*
****************************************************************************/
void GPM_ephList::copyData
/* ephemeris data unpacker
*/
(
GPM_ephData* pTemp
/* pointer to ephemeris data array
*/
)
{
pTemp->EphStruct.wn = *(sint16*)&m_TempArray[IDX_EPH_WN];
pTemp->EphStruct.toc = *(float*)&m_TempArray[IDX_EPH_TOC];
pTemp->EphStruct.toe = *(float*)&m_TempArray[IDX_EPH_TOE];
pTemp->EphStruct.af0 = *(float*)&m_TempArray[IDX_EPH_AF0];
pTemp->EphStruct.af1 = *(float*)&m_TempArray[IDX_EPH_AF1];
pTemp->EphStruct.af2 = *(float*)&m_TempArray[IDX_EPH_AF2];
pTemp->EphStruct.ura = *(float*)&m_TempArray[IDX_EPH_URA];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_E]);
pTemp->EphStruct.e = *(double*)&m_TempArray[IDX_EPH_E];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_SQRTA]);
pTemp->EphStruct.sqrta = *(double*)&m_TempArray[IDX_EPH_SQRTA];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_DN]);
pTemp->EphStruct.dn = *(double*)&m_TempArray[IDX_EPH_DN];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_M0]);
pTemp->EphStruct.m0 = *(double*)&m_TempArray[IDX_EPH_M0];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_W]);
pTemp->EphStruct.w = *(double*)&m_TempArray[IDX_EPH_W];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_OMG0]);
pTemp->EphStruct.omg0 = *(double*)&m_TempArray[IDX_EPH_OMG0];
cnvt_ieee_double((long *)&m_TempArray[IDX_EPH_I0]);
pTemp->EphStruct.i0 = *(double*)&m_TempArray[IDX_EPH_I0];
pTemp->EphStruct.odot = *(float*)&m_TempArray[IDX_EPH_ODOT];
pTemp->EphStruct.idot = *(float*)&m_TempArray[IDX_EPH_IDOT];
pTemp->EphStruct.cus = *(float*)&m_TempArray[IDX_EPH_CUS];
pTemp->EphStruct.cuc = *(float*)&m_TempArray[IDX_EPH_CUC];
pTemp->EphStruct.cis = *(float*)&m_TempArray[IDX_EPH_CIS];
pTemp->EphStruct.cic = *(float*)&m_TempArray[IDX_EPH_CIC];
pTemp->EphStruct.crs = *(float*)&m_TempArray[IDX_EPH_CRS];
pTemp->EphStruct.crc = *(float*)&m_TempArray[IDX_EPH_CRC];
pTemp->EphStruct.iod = *(unsigned char*)&m_TempArray[IDX_EPH_IOD];
return;
}
/*
190-00266-01
copyData
GPS 15H & 15L Technical Specifications
Page 32
*/
Rev. D
Each data member of the ephemeris data structure is indexed into the data array of the ephemeris packet
and cast as the appropriate data type. The indices are as follows (note that they correlate to the data
members of the structure respectively):
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
IDX_EPH_WN
IDX_EPH_TOC
IDX_EPH_TOE
IDX_EPH_AF0
IDX_EPH_AF1
IDX_EPH_AF2
IDX_EPH_URA
IDX_EPH_E
IDX_EPH_SQRTA
IDX_EPH_DN
IDX_EPH_M0
IDX_EPH_W
IDX_EPH_OMG0
IDX_EPH_I0
IDX_EPH_ODOT
IDX_EPH_IDOT
IDX_EPH_CUS
IDX_EPH_CUC
IDX_EPH_CIS
IDX_EPH_CIC
IDX_EPH_CRS
IDX_EPH_CRC
IDX_EPH_IOD
0
4
8
12
16
20
24
28
36
44
52
60
68
76
84
88
92
96
100
104
108
112
116
The last packet is a “download complete” packet that looks like this:
TX Packet: Download Complete
Byte Description
Delimiter
Download Complete ID
Number of bytes in data
Ephemeris Download ID
Pad
Checksum calculation
Delimiter
End of packet
Name
DLE
IOP_DL_CMPLT
SIZE
IOP_DOWN_LOAD_EPH
DATA
CHKSUM
DLE
ETX
HEX Value
0x10
0x0c
0x02
0x5D
0x00
---0x10
0x03
After properly acknowledging this packet (ACK the IOP_DL_CMPLT ID), the ephemeris download is
complete.
190-00266-01
GPS 15H & 15L Technical Specifications
Page 33
Rev. D
APPENDIX E: DECLARATION OF CONFORMITY
Hereby, Garmin Ltd., declares that this GPS 15H/15L is in compliance with the essential requirements and
other relevant provisions of Directive 1999/5/EC.
For the latest free software updates (excluding map data) throughout the life of your
Garmin products, visit the Garmin Web site at www.garmin.com.
© Copyright 2004–2006 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street, Olathe, Kansas 66062, U.S.A.
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9DL, U.K.
Garmin Corporation
No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
www.garmin.com
Part Number 190-00266-01 Rev. D