C-NaviGator I User Guide

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C-NaviGator I User Guide | Manualzz

C-NaviGator User Manual

Appendix A - Glossary of Terms

1PPS (1 Pulse Per Second) A precision electronic pulse output (at

TTL levels) from the GNSS receiver that marks exact second intervals (1 s). It is used for precise timing and to synchronize sensors and acquisition computers.

Azimuth The horizontal angle of the observer's bearing in surveying, measured clockwise from a referent direction, as from the north, or from a referent celestial body, usually Polaris.

Bad Packets The percentage of bad C-Nav correction packets received since the unit was turned on.

Bit Error Rate Number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors. The Bit

Error Rate is considered good if less than 20. The maximum reported value is 500.

C-Monitor A utility program used to monitor the quality of the position information received from a GNSS receiver. No position calculations are done in C-Monitor. C-Monitor simply creates a visual representation of the data received from a GNSS unit.

C-Nav The C-Nav GNSS receiver combines a dual-frequency, geodetic grade, GNSS receiver with an integrated LBAND communication RF detector and decoder -- all linked by an internal microprocessor. The entire assembly is combined into a single integrated package that is durable, lightweight and water/weatherproof.

C-Nav1010 The C-Nav GNSS receiver combines a dual-frequency, geodetic grade, GNSS receiver with an integrated LBAND communication RF detector and decoder -- all linked by an internal microprocessor. The entire assembly is combined into a single integrated package that is durable, lightweight and water/weatherproof.

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C-Nav2000 The C-Nav2000 GNSS navigational receiver is a 10-channel dual frequency unit with two additional channels for receiving Satellite Based

Augmentation System (SBAS) signals and an L-Band demodulator for reception of the C-Nav correction service. For more information, go to www.cnavGNSS.com

.

C-Nav2050 The C-Nav2050 survey GNSS receiver has expanded capabilities including RTK, PPS output, etc. As with the model

2000, the 2050 is a 10-channel, dual frequency, precision GNSS receiver, with two additional channels for receiving SBAS signals and an L-Band demodulator for reception of C-Nav subscription signals. Maximum data output rate is 50Hz and

Position Velocity Time (PVT) data can output at 25Hz. Two

115kbps serial ports are available. For more information, go to www.cnavGNSS.com

.

C-Nav3050 The C-Nav3050 survey GNSS receiver has expanded capabilities including RTK, PPS output, etc. As with other C-

Nav receivers, the C-Nav3050 includes dual frequency, precision GNSS receiver, with two additional channels for receiving SBAS signals and an L-Band demodulator for reception of C-Nav subscription signals. For more information, go to www.cnavGNSS.com

.

Correction Signal The Correction Signal-to-Noise ratio. This graph is only available with the C-Nav system.

Correction Type The type or source of differential corrections being applied to the GNSS receiver.

Course True The course computed by the GNSS receiver.

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Differential Age The time in seconds since the GNSS unit received the last differential correction update.

Differential GPS A technique for improving GPS solution accuracy by reducing the error based on signals received at a known location. Single point code positioning with pseudorange corrections are applied from simultaneous observations at the known position. One to ten meter accuracy is typical.

DOP Dilution of Precision is a scale factor representing the effect of satellite constellation geometry positioning accuracy.

Standard terms for GNSS applications are:

GDOP Geometric Dilution of Precision -- three coordinates plus clock offset

PDOP Position Dilution of Precision) -- three coordinates (See PDOP definition below)

HDOP coordinates

Horizontal Dilution of Precision -- two

VDOP

TDOP

Vertical Dilution of Precision -- height only

Time Dilution of Precision) -- clock offset only

Elevation

Error Ellipse

Height of the GNSS antenna above the reference ellipsoid.

A statistical measure of the positional error at a given point computed from the propagation of all errors affecting the position solution and expressed by its semi-major and semiminor axis (vectors of greatest and least magnitude) and the covariance (rotation angle in the reference coordinate system). Two-dimensional errors are typically propagated at one-standard deviation (39.4% probability that the position lies on or within the ellipse) or 2.1447 times the standard deviation (95% confidence) level.

FOM Figure of Merit

GNSS Receiver A GNSS receiver consists of a number of basic components: an antenna with optional preamplifier, a radio-frequency and

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C-NaviGator User Manual intermediate- frequency (RF/IF) "front end" section, a signal tracker/correlator section, and a micro- processor to control the receiver, process the signals, and compute the receiver's coordinates. The receiver will also include a power supply and memory devices to store instructions and data.

HAE Height Above Ellipsoid

– RTK vertical reference plane.

L1-L2 Sig. Strength GNSS satellites transmit spread spectrum signals in two frequency bands, L1 and L2 (1575.42 and 1223.6 MHz, respectively). The satellite signals carry both time information and a data strings, referred to as the GNSS navigation message. This message is transmitted at a rate of 50 bits per second. Using the data from 4 or more satellites, a GNSS receiver can accurately determine local latitude, longitude and height. Civilian applications are confined to the L1 band for computing position. The C & C

Technologies and military receivers employ both L1 and L2 bands, offering a significant improvement in accuracy.

NMEA 0183 This guideline for Interfacing marine electronics devices is a voluntary industry standard, first released in March of 1983.

NMEA 0183 defines electrical signal requirements, data transmission protocol, timing, and specific sentence formats for up to 38.4K-baud serial data bus.

PDOP Position Dilution of Precision is the most common mathematical expression of the quality of solutions. It is based on the geometry of the satellites with the best case being a value of 1. Higher numbers indicate worse quality.

The best DOP would occur with one satellite directly overhead and three others evenly spaced about the horizon.

PDOP has a multiplicative effect on range error. For example, a range error of 32 meters with a PDOP of 1 would give a user an assumed best accuracy of 32 meters. A

PDOP of 2 would result in an assumed accuracy of 64 meters. C-NaviGator can be programmed to stop providing position solutions above a specific PDOP level (6 is common).

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Position Includes Current Latitude, Longitude, Geoidal Height,

HDOP, PDOP, Type of corrections, Current Station ID,

Differential Age, Velocity, UTC Time and UTC Date if available.

PPS Precise Positioning Service

– a positioning service that includes velocity and timing information. PPS is continuously available, worldwide to authorized users. PPS information is usually (but not always) encrypted to prevent use by unauthorized users.

Pseudorange A measure of the apparent propagation time from the satellite to the receiver antenna, expressed as a distance.

The apparent propagation time is determined from the time shift required to align a replica of the GNSS code generated in the receiver with the received GNSS code. The time shift is the difference between the time of signal reception

(measured in the receiver time frame) and the time of emission (measured in the satellite time frame).

Pseudorange is obtained by multiplying the apparent signalpropagation time by the speed of light. Pseudorange differs from the actual range by the amount that the satellite and receiver clocks are offset, by propagation delays, and other errors including those introduced by selective availability.

PVT

RTCM

Position Velocity Time

Radio Technical Commission for Maritime Services)

– A

Commission set up to define a differential data link to relay

GNSS correction messages from a monitor station to a field user. The RTCM SC-104 recommendation is the defacto standard for differential GNSS correction transmission. It defines the correction message format and 16 different correction message types.

RTG Real Time Gypsy -- Developed by NASA's Jet Propulsion

Laboratory (JPL) to provide centimeter-level accuracy for space applications. A single RTG subscription service, combined with C-Nav hardware, can provide you with worldwide positioning capability on the order of 0.1 meter.

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RTK Real Time Kinematic (or Kinematic Surveying) involves a roving receiver that does not need to stop to collect precision information. Meter/centimeter level accuracy is available using modern dual-frequency carrier-phase measurement techniques.

SBAS Satellite Based Augmentation System - Includes, but is not limited to: WAAS (Wide Area Augmentation System) and

EGNOS (European Geo-stationary Navigation Overlay

System). Ranging signals generated on the ground and provided via C-band (or K-band) downlink are provided to the end user. These signals contain integrity data on satellite system.

Sky Plot This option displays a plot of the current GNSS satellite locations with reference to the GNSS receiver. C-NaviGator refers to this presentation as “Position Information”.

Scatter Plot This option displays a plot of satellite positions relative to the receiver and provides an indication of relative signal strength in the two frequency bands.

Visible Sats The number of Satellites used by the receiver in the position solution.

WAAS Wide Area Augmentation Service -- A system of satellites and ground stations that provide GNSS signal corrections over a wide area. An accuracy improvement on the order of three meters, with 95 percent confidence, is realized.

WCT Wide Area Correction Transform

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