OM-20000041 Rev 1 OM-20000041 REV 1 MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual GPSCard Products NovAtel Inc.
GPSCard MiLLennium Command Descriptions Manual Publication Number: Revision Level: OM-20000041 1 98/11/03 This manual reflects Software Version 4.50 Proprietary Notice Information in this document is subject to change without notice and does not represent a commitment on the part of NovAtel Inc.. The software described in this document is furnished under a licence agreement or non-disclosure agreement. The software may be used or copied only in accordance with the terms of the agreement.
Table of Contents TABLE OF CONTENTS TABLE OF CONTENTS Software License 9 Software Support 10 Foreword 11 Congratulations! ....................................................................................................................................... 11 Scope ........................................................................................................................................................ 11 Prerequisites ....................................................................
Table of Contents RTCM General Message Format ..................................................................................................48 RTCM Standard Commands ........................................................................................................49 RTCM Standard Logs ..................................................................................................................49 4.3 CMR Format Messaging ..........................................................................
Table of Contents RESET .......................................................................................................................................... 110 RESETHEALTH ......................................................................................................................... 111 RESETHEALTHALL ................................................................................................................. 111 RINEX ....................................................................
Table of Contents RALA/B .......................................................................................................................................186 RASA/B .......................................................................................................................................187 RBTA/B .......................................................................................................................................189 RCCA ...................................................
Table of Contents FIGURES 2-1 3-1 A-1 A-2 A-3 A-4 A-5 A-6 B-1 B-2 B-3 B-4 C-1 C-2 C-3 C-4 C-5 C-6 D-1 D-2 E-1 E-2 E-3 E-4 E-5 E-6 E-7 E-8 The WAAS Concept ................................................................................................................................. 29 Pass-Through Log Data ............................................................................................................................ 43 NAVSTAR Satellite Orbit Arrangement ....................................
Table of Contents TABLES 1-1 1-2 2-1 2-2 3-1 3-2 4-1 C-1 C-2 D-1 D-2 D-3 D-4 D-5 D-6 D-7 D-8 D-9 D-10 D-11 D-12 D-13 D-14 E-1 E-2 E-3 E-4 E-5 E-6 G-1 G-2 I-1 I-2 GPSCard Pseudorange Differential Initialization Summary .....................................................................16 Latency-Induced Extrapolation Error .......................................................................................................17 Commands By Function Table ...................................................
Software License SOFTWARE LICENSE SOFTWARE LICENSE BY OPENING THE SEALED DISK PACKAGE YOU ARE AGREEING TO BE BOUND BY THE TERMS OF THIS AGREEMENT. IF YOU DO NOT AGREE TO THE TERMS OF THIS AGREEMENT PROMPTLY RETURN THE UNOPENED DISK PACKAGE AND THE ACCOMPANYING ITEMS TO NOVATEL INC. 1. License: NovAtel Inc.
Software Support SOFTWARE SUPPORT SOFTWARE SUPPORT Software updates are software revisions to an existing model which improves (but does not increase) basic functionality of the GPS receiver. During the one year warranty coverage following initial purchase, software updates are supplied free of charge. After the warranty has expired, software updates and updated manuals may be subject to a nominal charge.
Foreword FOREWORD Congratulations! Thank you for purchasing a NovAtel GPSCard product. Whether you have bought a stand alone GPSCard or a packaged receiver you will have also received companion documents to this manual. They will help you get the hardware operational. Afterwards, this text will be your primary MiLLennium GPSCard command and logging reference source.
1 Quick Start 1 QUICK START 1 QUICK START This chapter will help you get started quickly regardless of whether you wish to carry out real-time kinematic (RTK) positioning, operate in differential modes or simply log data. Each section references additional sources of information. 1.1 INSTALLATION For more detailed instructions on the installation and set up of your GPSCard please refer to the accompanying MiLLennium GPSCard Guide to Installation and Operation.
1 Quick Start The View menu options allow you to select or de-select various visual aids and display screens. Take a look at all of the options and keep open those you wish to display. To send commands and log data the Command Console screen should be visible. ASCII format logs can be monitored on the ASCII Record screen. e.g. On the command line of the Command Console screen type:log com1 posa once After you hit the key the ASCII Record screen will display the output for your current position.
1 Quick Start Syntax: Syntax LOG port datatype trigger period offset hold log [port],datatype,[trigger],[period],[offset],{hold} Description COM1 or COM2 Defaults to the port that the command was entered on. Enter one of the valid ASCII or Binary Data Logs (see Chapter 4, Page 34 and Appendix D, Page 136) Enter one of the following triggers. ONCE Immediately logs the selected data to the selected port once. Default if trigger field is left blank.
1 Quick Start COMMONLY USED LOGS Type Logs Trigger Positioning PRTKA/B POSA/B ontime or onmark Post Processing RGEA/B/D REPA/B, ALMA/B ontime onchanged NMEA Position GPGLL GPGGA ontime or onmark Other useful logs are • • • • • RCCA to list the default command settings ETSA to monitor the channel tracking status SATA to observe the satellite specific data DOPA to monitor the dilution of precision of the current satellite constellation RVSA to monitor the receiver status For further information
1 Quick Start Table 1-1 GPSCard Pseudorange Differential Initialization Summary Reference Station Remote Station Required: Required: FIX POSITION lat lon hgt id (health) LOG port DATATYPE ontime 5 ACCEPT port DATATYPE Recommended Options: Recommended Options: LOG DATATYPES (binary): ACCEPT DATATYPES (binary): RTCMB RTCAB RTCM RTCA RTCM RTCA LOG DATATYPES (acii): ACCEPT COMMANDS (ascii): RTCMA RTCAA RTCMA RTCAA Related Commands/Logs: Related Commands/Logs: RTCMRULE DATUM POSA/B VLHA/B CDSA/B
1 Quick Start NOTE 1: Entry of the station ID and health are optional. For a CMR correction type the station ID must be < 31. NOTE 2: The accuracy of the reference station’s FIX POSITION setting will directly affect the accuracy of its computed differential corrections. Good results at the rover station are dependent on the reference station’s combined position errors being kept to a minimum (e.g., fix position error + multipath errors).
1 Quick Start Generally, a communications link capable of data throughput at a rate of 4800 bits per second or higher is sufficient. However, it is possible to satisfactorily use a lower rate (e.g. 2400 bps) with the RTCA, RTCM59 and CMR formats. RTCM Types 18 and 19 may require a higher rate; see Chapter 4, Message Formats, Page 45 for additional information. The minimum data transfer rate is based on the following: 1.
1 Quick Start used to adapt the system to a specific application. Some options apply only to the reference station, while others apply only to the remote station. Detailed descriptions can be found in Appendix C, Commands Summary. In the following sections, keep the following in mind: • Dynamics modes. For reliable performance the antenna should not move more than 1-2 cm when in static mode. See the RTKMODE commands in Chapter 2, Page 23 and Appendix C, Page 115 for more information.
1 Quick Start Example: fix position 51.11358042,-114.04358013,1059.4105,119,0 log com1,rtcm3,ontime,10 log com1,rtcm59,ontime,2 2.
1 Quick Start RTCM SC-104 is a standard for transmitting differential corrections between equipment from different manufacturers. The NovAtel GPSCard is capable of transmitting or receiving RTCM data. To facilitate transmitting the RTCM data over shared data links, the GPSCard is also capable of sending the RTCM log in NovAtel ASCII format (RTCMA) or with the NovAtel binary header (RTCMB) added to allow synchronous transmission and reception along with other data types.
1 Quick Start Establishing differential mode of operation at the rover receiver is primarily a one-step process whereby the accept command is used to enable reception of observation data from the reference station. ACCEPT COMMAND The accept command is primarily used to set the GPSCard’s COM port command interpreter for acceptance of various data formats (see the ACCEPT command in Chapter 2, Page 23 and Appendix C, Page 79).
2 Command Descriptions 2 COMMAND DESCRIPTIONS 2 COMMAND DESCRIPTIONS 2.1 GENERAL This section describes all commands accepted by the GPSCard with the exception of the "Special Data Input Commands". They are listed in alphabetical order. For descriptions of output logs using the LOG command, see Chapter 3. The GPSCard is capable of responding to over 50 different input commands. You will find that once you become familiar with these commands, the GPSCard offers a wide range in operational flexibility.
2 Command Descriptions NOTE: All previously stored configurations that were saved to non-volatile memory are erased (including Saved Config, Saved Almanac, and Channel Config). Example: Optional calculation of the checksum When an input command is followed by an optional checksum, the checksum will be verified before the command is executed. The checksum is the result of the logical exclusive-OR operation on all the bits in the message.
2 Command Descriptions 2.2 STANDARD COMMAND TABLES Table 2-1 lists the commands by function while Table 2-2 is an alphabetical listing of commands. Please see Appendix C, Page 79 for a more detailed description of individual commands which are listed alphabetically.
2 Command Descriptions Table 2-1 Commands By Function Table (continued) POSITION, PARAMETERS, AND SOLUTION FILTERING CONTROL Commands Descriptions 1 CSMOOTH DATUM Sets amount of carrier smoothing Choose a DATUM name type ECUTOFF FIX HEIGHT Satellite elevation cut-off for solutions Constrains to fixed height (2D mode) FIX POSITION Constrains to fixed lat, lon, height FRESET Clears all data which is stored in NVM $IONA Download ionospheric correction data What ionospheric correction to use (MiLLenn
2 Command Descriptions Table 2-1 Commands By Function Table (continued) DIFFERENTIAL REMOTE STATION Commands Descriptions ACCEPT $ALMA Accepts RTCM1, RTCA or RTCAB differential inputs Input almanac data DGPSTIMEOUT Set maximum age of differential data accepted RESET $RTCA Performs a hardware reset RTCA differential correction input (ASCII) $RTCM RTCMRULE RTCM differential correction input (ASCII) Selects RTCM bit rule SETDGPSID Select differential reference station ID to receive CLOCK INFORMATIO
2 Command Descriptions DIFF_PROTOCOL Differential correction message encoding and decoding for implementation in the GPS card firmware diff_protocol type key or diff_protocol disable or diff_protocol DYNAMICS Set receiver dynamics dynamics option [user_dynamics] ECUTOFF Set elevation cutoff angle ecutoff angle EXTERNALCLOCK Sets default parameters of an optional external oscillator externalclock option EXTERNALCLOCK FREQUENCY Sets clock rate external frequency clock rate FIX HEIGHT Sets hei
2 Command Descriptions 2.3 WAAS The Wide Area Augmentation System (WAAS) is a safety-critical system that provides a quality of positioning information previously unavailable. The WAAS improves the accuracy, integrity, and availability of the basic GPS signals. In the future, the wide area of coverage for this system will include the entire United States and some outlying areas.
2 Command Descriptions The signal broadcast via the WAAS GEOs to the WAAS users is designed to minimize modifications to standard GPS receivers. As such, the GPS L1 frequency (1575.42 MHz) is used, together with GPS-type modulation - e.g. a Coarse/Acquisition (C/A) pseudorandom (PRN) code. In addition, the code phase timing is maintained close to GPS time to provide a ranging capability. 2.3.1 WAAS GPSCard NovAtel has developed several models of WAAS-capable MiLLennium GPSCards that process WAAS signals.
2 Command Descriptions The GPSCard is capable of logging almanac data utilizing the NovAtel-format ASCII log command option ALMA. Once logged, the data records will precede the header with the $ character (e.g., $ALMA). There are no specific NovAtel log option commands to independently specify output of ionospheric or UTC parameters. These parameters will always output following the $ALMA log (identifiable by the headers $IONA and $UTCA respectively).
2 Command Descriptions $UTCA... Use this special data input command to quickly update the GPSCard Universal Time Coordinated (UTC) parameters following a system restart (always appended to $ALMA records unless intentionally stripped). The UTC data is required before the GPSCard can accurately compute UTC time. If not input with $UTCA, it may take up to 12.5 minutes after a reset for the GPSCard to receive current UTCA data.
2 Command Descriptions Appendix D, Page 192. An example of a $REPA data message is as follows: $REPA,14,8B09DC17B9079DD7007D5DE404A9B2D04CF671C6036612560000021804FD, 8B09DC17B98A66FF713092F12B359DFF7A0254088E1656A10BE2FF125655, 8B09DC17B78F0027192056EAFFDF2724C9FE159675A8B468FFA8D066F743*57[CR][LF] $RTCA... (RTCAA) Use this special data input command to directly input NovAtel RTCAA differential corrections data, ASCII format. The data can be accepted using COM1 or COM2.
3 Data Logs 3 DATA LOGS 3 DATA LOGS 3.1 OUTPUT LOGGING The GPSCard provides versatility in your logging requirements. You can direct your logs to either COM1 or COM2, or both ports, as well as combine data types.
3 Data Logs command. If trigger type is specified in the LOG syntax, the log will continue to be output based on the trigger specification. Specific logs can be disabled using the UNLOG command, whereas all enabled logs will be disabled by using the UNLOGALL command (see Chapter 2, Page 23 and Appendix C, Page 132). All activated logs will be listed in the receiver configuration status log (RCCA). 3.
3 Data Logs The following table describes the format types used in the description of binary logs. Type Size (bytes) Size (bits) char 1 8 int 4 32 double 8 64 float 4 32 Description The char type is used to store the integer value of a member of the representable character set. That integer value is the ASCII code corresponding to the specified character. The size of a signed or unsigned int item is the standard size of an integer on a particular machine.
3 Data Logs 3.4 NMEA FORMAT DATA LOGS General The NMEA log structures follow format standards as adopted by the National Marine Electronics Association. The reference document used is "Standard For Interfacing Marine Electronic Devices NMEA 0183 Version 2.00". For further information, see Appendix F, Standards and References, Page 233. The following table contains excerpts from Table 6 of the NMEA Standard which defines the variables for the NMEA logs.
3 Data Logs GPS time is based on an atomic time scale. Universal Time Coordinated (UTC) time (reported in NMEA logs) is also based on an atomic time scale, with an offset of seconds applied to coordinate Universal Time to GPS time. GPS time is designated as being coincident with UTC at the start date of January 6, 1980 (00 hours). GPS time does not count leap seconds, and therefore an offset exists between UTC and GPS time.
3 Data Logs Table 3-1 Logs By Function Table (continued) Logs SATELLITE TRACKING AND CHANNEL CONTROL Descriptions ALMA/B DOPA/B Current decoded almanac data DOP of SVs currently tracking ETSA/B Provides channel tracking status information for each of the GPSCard parallel channels GPALM NMEA, almanac data GPGSA GPGSV NMEA, SV DOP information NMEA, satellite-in-view information RALA/B Raw almanac RASA/B RGEA/B/D Raw GPS almanac set Satellite range measurements SATA/B SBTA/B Satellite specific i
3 Data Logs Table 3-1 Logs By Function Table (continued) DIFFERENTIAL REMOTE STATION Descriptions Logs CDSA/B Communication and differential decode status GPGGA GGAB NMEA, position fix data NovAtel binary version of GPGGA POSA/B Position information PRTKA/B Computed Position – best available RTKA/B Computed Position – Time Matched RTKOA/B SATA/B RTK Output Satellite specific information SVDA/B VLHA/B SV position in ECEF XYZ with corrections Velocity, latency & direction over ground POST PROCE
3 Data Logs Table 3-2 GPSCard Log Summary Syntax: log port,datatype,[trigger],[period],[offset],{hold} NovAtel Format Logs Datatype Description Datatype Description ALMA/B Decoded Almanac RASA/B Raw GPS Almanac Set BSLA/B Baseline Measurement RCCA Receiver Configuration CDSA/B Communication and Differential Decode Status REPA/B Raw Ephemeris CLKA/B Receiver Clock Offset Data RGEA/B/D Channel Range Measurements CLMA/B Receiver Clock Model RPSA/B Reference Station Position and Health C
3 Data Logs 3.7 WAAS The Wide Area Augmentation System (WAAS) is a safety-critical system that provides a quality of positioning information previously unavailable. The WAAS improves the accuracy, integrity, and availability of the basic GPS signals. 3.7.1 WAAS GPSCard Logs The log WALA/B (see its descriptions on Page 222), provide WAAS satellite-specific data. For more information on MiLLennium GPSCards with the WAAS option, see Page 29. 3.
3 Data Logs Figure 3-1 Pass-Through Log Data $PVAA data log Data Link To COM1 To COM1 To COM2 To COM2 fix position (lat,lon,ht,id) accept com1 none log com1 pvaa ontime 5 messages com1 off log console com1a onchanged Serial Cable Serial Cable Host PC (Rover Station) Host PC (Reference Station) When pass-through logs are being used, the GPSCard’s command interpreter continues to monitor the port for valid input commands and replies with error messages when the data is not recognized as such.
3 Data Logs Example 1: $COM1,747,347131.23,$TM1A,747,347131.000000000,0.000000058,0.00000 0024, -9.000000009,0*78*2E[CR][LF] $COM1,747,347131.31,*4F[CR][LF] $COM1,747,347131.40,Invalid Command Option*7C[CR][LF] $COM1,747,347131.42,Com1>Invalid Command Option*30[CR][LF] $COM1,747,347131.
4 Message Formats 4 MESSAGE FORMATS 4 MESSAGE FORMATS In a NovAtel RTK positioning system, the observations transmitted by a NovAtel reference station to a NovAtel remote station can be in either a proprietary RTCA Type 7 or a proprietary RTCM Type 59N message format. A NovAtel Rover station is also able to receive CMR-format messages, Section 4.3, from a non-NovAtel base station.
4 Message Formats RTCAREF TYPE 7 An RTCAREF (RTCA Reference Station Position Information) message contains reference station position information, and should be sent once every 10 seconds. Each message is 24 bytes (192 bits) long. If RTCA-format messaging is being used, the optional station id field that is entered using the FIX POSITION command can be any 4-character string combining numbers and upper-case letters, and enclosed in quotation marks (e.g. “RW34”).
4 Message Formats NovAtel header and terminates with a checksum. This message was designed so that RTCA data can be intermixed with other NovAtel ASCII data over a common communications port. The log is not in pure RTCA format. The header ($RTCA) and terminator (*xx) must be stripped off at the receiving end, then the data will need to be converted from hexadecimal to binary before the RTCA information is retrieved.
4 Message Formats The standards recommended by the Radio Technical Commission for Maritime Services Special Committee 104, Differential GPS Service (RTCM SC-104,Washington, D.C.), have been adopted by NovAtel for implementation into the GPSCard. Because the GPSCard is capable of utilizing RTCM formats, it can easily be integrated into positioning systems around the globe.
4 Message Formats RTCM Standard Commands RTCMRULE The RTCM standard states that all equipment shall support the use of the "6 of 8" format (data bits a1 through a6 where bits a1 through a6 are valid data bits and bit a7 is set to mark and bit a8 is set to space). The GPSCard RTCMRULE command allows for flexibility in the use of the bit rule to accommodate compatibility with equipment that does not strictly adhere to the RTCM stated rule.
4 Message Formats convention, an “A” at the end of the log name denotes the NovAtel ASCII version (e.g. RTCM1A), and a “B” denotes the NovAtel binary version (e.g. RTCM1B). These logs contain the same data that is available in the corresponding RTCM Standard Format messages; however, the data has been “packaged” into NovAtel-format messages. These NovAtel-format logs are not in pure RTCM SC-104 format and are not directly usable as such.
4 Message Formats generating this Type 1 log. The log is of variable length, depending on the number of satellites visible and pseudoranges corrected by the reference station. Satellite specific data begins at word 3 of the message.
4 Message Formats This message was designed so that RTCM data can be transmitted intermixed with other NovAtel binary data over a common communications port. The log is not in pure RTCM SC104 format and is not directly usable as such. GPSCard remote receivers cannot decode or interpret the RTCMB data (however, the GPSCard can directly interpret RTCM and RTCMA). The 12 byte NovAtel binary header must be stripped off before the RTCM information can be retrieved.
4 Message Formats RTCM9 PARTIAL SATELLITE SET DIFFERENTIAL CORRECTIONS RTCM Type 9 messages follow the same format as Type 1 messages. However, unlike Type 1 messages, Type 9’s do not require a complete satellite set. This allows for much faster differential correction data updates to the remote stations, thus improving performance and reducing latency. Type 9 messages should give better performance when SA rate correction variations are high, or with slow or noisy data links.
4 Message Formats $RTCM16,6649404045495E5A5C406A58696D76596D5F665F765869694D4E53604D 70696552567E7B675762747B67576C574E596F59697146555A75516F5F667D4967 5656574E53604D55565A6D69647B67777E454659685D56465A67616E4B7E7F7F7D *52[CR][LF] RTCM16B This message is the binary code equivalent of the special message entered using the RTCM16T command.
4 Message Formats capable of operating in RT-20 Carrier Phase Differential Positioning Mode. This log is primarily used by a GPSCard reference station to broadcast its RT-20 observation data (delta pseudorange and accumulated Doppler range) to remote RT-20 – capable GPSCard receivers. NOTE 1: The CDSA/B log is very useful for monitoring the serial data link, as well as differential data decode success. NOTE 2: This log is intended for use when operating in RT-20 mode.
4 Message Formats Using RT-2 or RT-20 with CMR Format Messages To enable receiving CMR messages, follow these steps: 1. Issue the COMn command to the rover receiver to set its serial port parameters to the proper bit rate, parity, etc. This command is described in detail on Page 84. 2. Issue the “ACCEPT COMn CMR” command to the rover receiver, where “COMn” refers to either the COM1 or COM2 serial port that is connected to the data link.
4 Message Formats COM1> log com2 rinex ontime 30 (some time later - move to a new site) COM1> log com2 xkin COM1> rinex markernum 980.1.35 COM1> rinex antdh 3.1 (at new site) COM1> log com2 xsta (some time later - logging complete) COM1> unlogall It should be noted that the first line of this example is equivalent to these two lines: COM1> log com2 xobs ontime 30 COM1> log com2 xnav onchanged The use of the pseudo-log RINEX is for convenience only.
4 Message Formats Command example: COM1> rinex agency NovAtel Surveying Service Ltd. COM1> rinex antde -0.05 COM1> rinex antdh 2.7 COM1> rinex antdn 0.1 COM1> rinex antnum Field #1 COM1> rinex anttype NovAtel 501 COM1> rinex comment Field trial of new receiver COM1> rinex markname A980 COM1> rinex markernum 980.1.34 COM1> rinex observer S.C. Lewis COM1> rinex recnum LGN94100019 COM1> log com1 rcca Log example: $RCCA,COM1,9600,N,8,1,N,OFF,OFF*65 ... etc....
4 Message Formats Log example: $XOBS, 96 04 10 17 25 19.5000000 2*00 $XOBS, $XOBS, 4 *** KINEMATIC DATA FOLLOWS *** 1*2F COMMENT*50 XNAV NAVIGATION DATA RECORD This log type contains broadcast navigation message records for each satellite being used.
4 Message Formats Command example: COM1> log com2 xobs ontime 5 Log example: $XOBS, 96 04 10 16 12 45.0000000 0 10G22G29G 3G28G16G27G 2G18G31G19*2B $XOBS, 25589487.514 1 134473357.195 11 3689.020 1*20 $XOBS, 24031521.036 7 126285967.262 7 3673.582 7*3E $XOBS, 22439789.377 9 117921029.600 9 270.081 9*2A $XOBS, 22766999.777 9 119640447.360 9 924.831 9*28 $XOBS, 23387648.507 6 122901958.756 6 -640.482 6*2F $XOBS, 21889019.606 8 115027300.270 8 -2682.
4 Message Formats XSTA OBSERVATION STATIC EVENT This log generates a time tag and flag when a new site occupation begins. Command example: COM1> log com2 xsta Log example: $XOBS, 96 04 10 17 25 45.0000000 3 $XOBS,A980 $XOBS,980.1.35 $XOBS, 3.1000 $XOBS, *** NEW SITE OCCUPATION *** 4*39 0.0500 0.1000 MARKER NAME*7F MARKER number*0D ANTENNA: DELTA H/E/N*4C COMMENT*19 MiLLennium GPSCard Software Version 4.
A GPS Overview A GPS OVERVIEW A GPS OVERVIEW The Global Positioning System (GPS) is a satellite navigation system capable of providing a highly accurate, continuous global navigation service independent of other positioning aids. GPS provides 24-hour, all-weather, worldwide coverage with position, velocity and timing information.
A GPS Overview the Space Vehicle Number (SVN) or the Pseudorandom Code Number (PRN). The GPSCard. PRN is used by the NovAtel The GPS satellites transmit on two L-band frequencies; one centered at 1575.42 MHz (L1) and the other at 1227.60 MHz (L2). The L1 carrier is modulated by the C/A code (Coarse/Acquisition) and the P code (Precision) which is encrypted for military and other authorized users. The L2 carrier is modulated only with the P code.
A GPS Overview Figure A-2 Illustration of GPSCard Height Measurements Notes: References: h=H+N N=h-H 1 Topography 2 Geoid (mean sea level) 3 Spheroid (ellipsoid) H = GPSCard computed height above/below geoid N = Geoidal Height (undulation) h = GPS system computed height above the spheroid From the above diagram, and the formula h = H + N, to convert heights between the ellipsoid and geoid we require the geoid-ellipsoid separation value. This value is not easy to determine.
A GPS Overview Figure A-3 Accuracy versus Precision5 High accuracy, high precision Low accuracy, high precision High accuracy, low precision Low accuracy, low precision Single-point vs. Relative Positioning In single-point positioning, coordinates of a GPS receiver at an unknown location are sought with respect to the earth’s reference frame by using the known positions of GPS satellites being tracked.
A GPS Overview Figure A-4 Example of Differential Positioning GPS satellites GPS antenna Differential data User with hand-held computer Radio RX GPS RX Remote station GPS antenna (shown with choke-ring ground plane) Radio TX GPS RX Reference station Static vs. Kinematic Positioning Static and kinematic positioning refer to whether a GPS receiver is stationary or in motion while collecting GPS data. Real-time vs.
A GPS Overview 1. The matched position solution is computed at the remote station when the observation information for a given epoch has arrived from the reference station via the data link. Matched observation set pairs are observations by both the reference and remote stations which are matched by time epoch, and contain the same satellites.
A GPS Overview • Ionospheric Group Delays – The earth’s ionospheric layers cause varying degrees of GPS signal propagation delay. Ionization levels tend to be highest during daylight hours causing propagation delay errors of up to 30 meters, whereas night time levels are much lower and may be up to 6 meters. • Tropospheric Refraction Delays – The earth’s tropospheric layer causes GPS signal propagation delays which bias the range measurements.
A GPS Overview a specified number of hours or until the averaged position is within specified accuracy limits. Averaging will stop when the time limit or the horizontal standard deviation limit or the vertical standard deviation limit is achieved. When averaging is complete, the FIX POSITION command will automatically be invoked. If the maximum time is set to 1 hour or larger, positions will be averaged every 10 minutes and the standard deviations reported in the PAVA/B log should be correct.
A GPS Overview satellite constellation. The graph, however, should at least provide some indication of the accuracy one may expect from single point position averaging. Dual Station Differential Positioning It is the objective of operating in differential mode to either eliminate or greatly reduce most of the errors introduced by the above types of system biases.
A GPS Overview THE REFERENCE STATION The nucleus of the differential network is the reference station. To function as a base station, the GPS receiver antenna must be positioned at a control point whose position is precisely known in the GPS reference frame. Typically, the fixed position will be that of a geodetic marker or a pre-surveyed point of known accuracy.
A GPS Overview ADRdouble difference = (ADRrx A,sat i - ADRrx A,sat j) - (ADRrx B,sat i - ADRrx B,sat j) An ambiguity value is estimated for each double-difference observation. One satellite is common to every satellite pair; it is called the reference satellite, and it is generally the one with the highest elevation. In this way, if there are n satellites in view by both receivers, then there will be n-1 satellite pairs.
B Multipath Elimination Technology B Multipath Elimination Technology B MULTIPATH ELIMINATION TECHNOLOGY Multipath signal reception is one of the most plaguing problems that detracts from the accuracy potential of GPS pseudorange differential positioning systems. This section will provide a brief look at the problems of multipath reception and some solutions developed by NovAtel. B.
B Multipath Elimination Technology settings as well. If the GPS receiver is in a valley with nearby hills, mountains and heavy vegetation, signal obstruction and attenuation are also very common. Consequences of Multipath Reception Because GPS is a radio ranging and positioning system, it is imperative that ground station signal reception from each satellite be of direct line of sight. This is critical to the accuracy of the ranging measurements.
B Multipath Elimination Technology and at all bearings and elevation angles from the antenna. This is, of course, the ideal situation, which may not be possible under actual operating conditions. Try to place the antenna as far as possible from obvious reflective objects, especially reflective objects that are above the antenna’s radiation pattern horizon. Another solution would be to install an RF fence pointing toward the reflector which is causing the multipath.
B Multipath Elimination Technology Figure B-3 Illustration of Quadrifilar vs. Microstrip Patch Antennae Quadrifilar Elements Radome Antenna Patch Dielectric Patch Ground Plane Quadrifilar Helix Antenna Microstrip Patch Antenna Antenna Ground Planes Nearby objects can influence the radiation pattern of an antenna.
B Multipath Elimination Technology the part of the GPS user. This is what makes NovAtel’s internal receiver solutions so desirable and practical. NovAtel has placed long term concerted effort into the development of internal receiver solutions and techniques that achieve multipath reduction, all of which are transparent to the GPSCard user. These achievements have led to Narrow Correlator tracking technology. It utilizes innovative patented correlator delay lock loop (DLL) techniques.
B Multipath Elimination Technology Figure B-4 Comparison of Multipath Envelopes SUMMARY Any localized propagation delays or multipath signal reception cause biases to the GPS ranging measurements that cannot be differenced by traditional DGPS single or double differencing techniques. Generally speaking, single point positioning systems are not too concerned with multipath reception, as the system errors are quite large to begin with.
C C C Commands Summary COMMANDS SUMMARY COMMANDS SUMMARY ACCEPT The ACCEPT command controls the processing of input data and is primarily used to set the GPSCard’s COM port command interpreter for acceptance of various data formats. Each port can be controlled to allow ASCII command processing (default), binary differential data processing, or the command interpreter can be turned off.
C Commands Summary Syntax: ACCEPT Syntax ACCEPT port option (GPSCard model dependent) port option Range Value COM1 or COM2 NONE COMMANDS RTCA RTCM CMR Description Command Specifies the COM port to be controlled Turn off Command Interpreter Command Interpreter attempts to interpret all incoming data. Will also interpret certain ASCII and NovAtel format binary logs.
C Commands Summary ANTENNAPOWER On MiLLennium GPSCards this command enables or disables the supply of electrical power from the internal power source of the card to the low-noise amplifier (LNA) of an active antenna. Jumper P301 allows the user to power the LNA either by an internal power source (plug connects pins 1&2) or an optional external power source (plug connects pins 2&3); or, the user can cut off all power to the antenna (plug removed).
C Commands Summary ASSIGN This command may be used to aid in the initial acquisition of a satellite by allowing you to override the automatic satellite/channel assignment and reacquisition processes with manual instructions. The command specifies that the indicated tracking channel search for a specified satellite at a specified Doppler frequency within a specified Doppler window. The instruction will remain in effect for the specified channel and PRN, even if the assigned satellite subsequently sets.
C Commands Summary CLOCKADJUST All oscillators have some inherent drift. On the MiLLennium GPSCard, the clock and the PPS strobe have a 50 ns jitter due to the receiver’s attempts to keep the clock as close as possible to GPS time. This option is disabled by entering CLOCKADJUST DISABLE. The jitter will vanish, but the unsteered and free-running clock will drift relative to GPS time.
C Commands Summary COMn This command permits you to configure the GPSCard COM port’s asynchronous drivers.
C OUTPUT DATA DTR Commands Summary Data 150 ms 300 ms tail lead control COMn_RTS This command enables versatile control of the RTS handshake line for use with output data logging in conjunction with external devices such as a radio transmitter. The default state for the COM1 or COM2 RTS line is always high. COMn_RTS will not influence the COMn command handshake control of incoming commands.
C Commands Summary CONFIG This command switches the channel configuration of the GPSCard between pre-defined configurations. When invoked, this command loads a new satellite channel-configuration and forces the GPSCard to reset. The types of configurations possible are listed by entering this command: HELP CONFIG In some applications, only the standard (default) configuration will be listed in response. configuration of a MiLLennium GPSCard consists of 12 L1/L2 channel pairs.
C Commands Summary CRESET Configuration Reset. Resets user configuration to the factory default. After a reset, non volatile memory (NVM) is read for user configuration. This command does not reset the hardware. See the Factory Default Settings . Syntax: CRESET See also the FRESET and RESET commands. These three commands differ in the following way: RESET - Resets the hardware. Similar to powering the card off and on again. CRESET - Resets user configuration to the factory default.
C Commands Summary CSMOOTH This command sets the amount of carrier smoothing to be performed on the pseudorange measurements carrier. An input value of 100 corresponds to approximately 100 seconds of smoothing. Upon issuing the command, the locktime for all tracking satellites is reset to zero. From this point each pseudorange smoothing filter is restarted. The user must wait for at least the length of smoothing time for the new smoothing constant to take full effect.
C Commands Summary DATUM This command permits you to select the geodetic datum for operation of the receiver. If not set, the value is defaulted to WGS84. See Table G-2 in Appendix G for a complete listing of all available predefined datums. See the USERDATUM command for user definable datums. The datum you select will cause all position solutions to be based on that datum (except PXYA/B which is always based on WGS84).
C Commands Summary DGPSTIMEOUT This command has a two-fold function: (1) to set the maximum age of differential data that will be accepted when operating as a remote station. Differential data received that is older than the specified time will be ignored. When entering DGPS delay, you can ignore the ephemeris delay field. (2) to set the ephemeris delay when operating as a reference station.
C Commands Summary DIFF_PROTOCOL Differential Protocol Control NOTE: The DIFF_PROTOCOL command should only be used by advanced users of GPS. Features: 1. A user definable key such that many different types of encoding may be used in the same area without cross talk between the various “channels”. 2. Encodes all correction data following any header specific to the message type. 3. Non-volatile.
C Commands Summary DYNAMICS This command informs the receiver of user dynamics. It is used to optimally tune receiver parameters. Syntax: DYNAMICS user_dynamics Command DYNAMICS user_dynamics Description Command air land foot receiver is an aircraft receiver is in a land vehicle with velocity less than 110 km/h (30m/s) receiver is being carried by a person with velocity less than 11 km/h (3m/s) Default dynamics air Example: dynamics foot 92 MiLLennium GPSCard Software Version 4.
C Commands Summary ECUTOFF This command sets the elevation cut-off angle for usable satellites. The GPSCard will not start tracking a satellite until it rises above the cutoff angle. If there are six or less satellites being tracked and one drops below this angle, it will continue to be tracked until the signal is lost. However, if there are more than six satellites being tracked, any that are below the cutoff angle will be dropped completely.
C Commands Summary EXTERNALCLOCK Overview The EXTERNALCLOCK and EXTERNALCLOCK FREQUENCY commands allows the MiLLennium GPSCard to operate with an optional external oscillator. The user is able to optimally adjust the clock model parameters of the GPSCard for various types of external clocks. The three-state clock model on GPSCards having access to this command is different from that used on the other GPSCards. NOTE: The EXTERNALCLOCK command will affect the interpretation of the CLKA/B log.
C Commands Summary Syntax: EXTERNALCLOCK Command EXTERNALCLOCK option Option disable ocxo rubidium cesium user h0 h-1 h-2 Description Default Revert to the on-board oscillator MiLLennium = VCTCXO Set defaults for ovenized crystal oscillator Set defaults for rubidium oscillator Set defaults for cesium oscillator Define custom values for process noise elements see Table C-2 Example: externalclock user 1.0e-20 1.0e-24 1.
C Commands Summary EXTERNALCLOCK FREQUENCY Please see the Overview and Theory sub-sections under the EXTERNALCLOCK command to understand the steps involved in using an optional external oscillator with a MiLLennium GPSCard. For the chosen oscillator, one must select the clock rate using the EXTERNALCLOCK FREQUENCY command. The MiLLennium GPSCard only accepts a 5 MHz or 10 MHz external input.
C Commands Summary FIX HEIGHT This command configures the GPSCard in 2D mode with its height constrained to a given value. The command would be used mainly in marine applications where height in relation to mean sea level may be considered to be approximately constant. The height entered using this command is always referenced to the geoid (mean sea level, see the PRTKA/B log in Chapter 4 and Appendix D) and uses units of meters.
C Commands Summary FIX POSITION Invoking this command will result in the GPSCard position being held fixed. A computation will be done to solve local clock offset, pseudorange, and pseudorange differential corrections. This mode of operation can be used for time transfer applications where the position is fixed and accurate GPS time output is required (see the CLKA/B and TM1A/B logs, Appendix D for time data).
C Commands Summary FIX VELOCITY This command supports INS (Inertial Navigation System) integration. It accepts ECEF XYZ velocity values in units of meters per second (m/s). This information is only used by the tracking loops of the receiver to aid in reacquisition of satellites after loss of lock, otherwise it is ignored. It is not used in the position solution and velocity calculations.
C Commands Summary FREQUENCY_OUT This command allows the user to specify the frequency of the output pulse train available at the variable frequency (VARF) pin of the I/O strobe connector. This command has no effect on the operation of the GPSCard; it is only provided for user-determined applications.
C Commands Summary FRESET This command clears all data which is stored in non-volatile memory. Such data includes the almanac, satellite channel configuration, and any user-specific configurations. The GPSCard is forced to reset and will start up with factory defaults. See also the CRESET, where the differences between these three commands are explained, and RESET commands. Syntax: FRESET MiLLennium GPSCard Software Version 4.
C Commands Summary HELP This command provides you with on-line help. The command, with no options, gives a complete list of the valid system commands. For detailed help on any command, append the optional command name to the HELP command. Syntax: HELP OR: option ? option Syntax HELP (or ?) option Range Value See Figure C-1 Description Entering HELP without an option will list all valid command options. Can be any valid system command. Information about the command entered will be displayed.
C Commands Summary IONOMODEL WAAS This command allows the user to decide what ionospheric corrections the card uses. This command currently does not effect the ionospheric model that is used when the card is operating in RTK mode. Additional range values are reserved for future use. The MiLLennium by default computes ionospheric corrections using L1 & L2 signals; to use the ionospheric corrections issued by the WAAS GEO satellite, you need to issue the IONOMODEL WAAS command.
C Commands Summary LOCKOUT This command will prevent the GPSCard from using a satellite by de-weighting its range in the solution computations. Note that the LOCKOUT command does not prevent the GPSCard from tracking an undesirable satellite. This command must be repeated for each satellite to be locked out. See also the UNLOCKOUT and UNLOCKOUTALL commands.
C Commands Summary LOG Many different types of data can be logged using several different methods of triggering the log events. Every log element can be directed to either the COM1 or COM2 ports. If a selected log element is to be directed to all the ports, then separate LOG commands are required to control them. The ONTIME trigger option requires the addition of the period parameter and optionally allows input of the offset parameter.
C Commands Summary MAGVAR The GPSCard computes directions referenced to True North. Use this command (magnetic variation correction) if you intend to navigate in agreement with magnetic compass bearings. The correction value entered here will cause the "bearing" field of the NAVA/B and GPVTG logs to report bearing in degrees Magnetic. The magnetic variation correction is also reported in the GPRMC log. The GPSCard will compute the magnetic variation correction if you use the auto option.
C Commands Summary Figure C-3 Illustration of Magnetic Variation & Correction MiLLennium GPSCard Software Version 4.
C Commands Summary MESSAGES The MESSAGES command is used to disable the port prompt and error message reporting from a specified port. This feature can be useful if the port is connected to a modem or other device that responds with data the GPSCard does not recognize. See Chapter 3 for further information on using this command with Special Pass-Through Logs.
C Commands Summary POSAVE This command implements position averaging for reference stations. Position averaging will continue for a specified number of hours or until the averaged position is within specified accuracy limits. Averaging will stop when the time limit or the horizontal standard deviation limit or the vertical standard deviation limit is achieved. When averaging is complete, the FIX POSITION command will automatically be invoked.
C Commands Summary RESET This command performs a hardware reset. Following a RESET command, the GPSCard will initiate a cold-start bootup. Therefore, the receiver configuration will revert to the factory default if no user configuration was saved or the last SAVECONFIG settings. Syntax: RESET See also the CRESET, where the differences between these three commands are explained, and FRESET commands. 110 MiLLennium GPSCard Software Version 4.
C Commands Summary RESETHEALTH This command cancels the SETHEALTH command and restores the health of a satellite to the broadcast value contained in the almanac and ephemeris data. Syntax: RESETHEALTH Syntax prn Range Value RESETHEALTH prn 1 - 32 Description Command The PRN integer number of the satellite to be restored. Example: resethealth 4 RESETHEALTHALL This command resets the health of all satellites to the broadcast values contained in the almanac and ephemeris data.
C Commands Summary RINEX Receiver-Independent Exchange Format The RINEX format is a broadly-accepted, receiver-independent format for storing GPS data. It features a nonproprietary ASCII file format that can be used to combine or process data generated by receivers made by different manufacturers. RINEX was originally developed at the Astronomical Institute of the University of Berne. Version 2, containing the latest major changes, appeared in 1990; subsequently, minor refinements were added in 1993.
C Commands Summary RTCM16T This is a NovAtel command relating to the RTCM Standard ASCII message that can be sent out in RTCM Type 16 format. Once created, the RTCM16T message can be viewed in the RCCA command settings list. The text message can also be logged using the RTCM16 or RTCM16T log option. This command will limit the input message length to a maximum of 90 ASCII characters. See Chapter 4, for related topics. MiLLennium GPSCard Software Version 4.
C Commands Summary RTCMRULE This command allows the user flexibility in the usage of the RTCM Standard "bit rule". See Chapter 4, for further information. 114 MiLLennium GPSCard Software Version 4.
C Commands Summary RTKMODE This command sets up the RTK (RT-2 or RT-20) mode. Invoking this command allows you to set different parameters and control the operation of the RTK system. The RTKMODE command is actually a family of commands; a description of the various arguments and options is as follows. Some arguments require data input, while others do not. Certain arguments can be used only at the reference station, and others only at the remote station.
C Commands Summary Command Argument Default Argument Data Range RTKMODE default enable or disable reset auto, static or kinematic fixed or float unknown_baseline, default enable auto fixed unknown_baseline known_llh_position lat,lon,hgt,[2σ],[m/e] or lat: 0 to ± 90 lon: 0 to ± 360 hgt: -1000 to +20 000 000 2σ: 0 to 0.03 m/e: m or e (m = default) known_ecef_baseline ∆x, ∆y,∆z,[2σ] (∆x)2 + (∆y)2 +(∆z)2 ≤ (1 000 000)2 2σ: 0 to 0.
C Station Remote Command rtkmode Argument Commands Summary Data unknown_baseline (default) known_llh_position lat,lon,height,[2σ],[m/e] known_ecef_baseline ∆x, ∆y, ∆z,[2σ] RTKMODE UNKNOWN_BASELINE prevents the RTK system from using any baseline information in the initial calculation of ambiguities. It cancels the effect of the RTKMODE KNOWN_LLH_POSITION or RTKMODE KNOWN_ECEF_BASELINE command.
C Commands Summary Station Remote Command rtkmode Argument auto (default) static kinematic RTKMODE AUTO configures the RTK system to automatically detect motion. It is the default mode. It will reliably detect motion of 2.5 cm/sec or greater. If you are undergoing motion slower than this which covers more than 2 cm, you should use the manual mode selection commands (static and kinematic).
C Commands Summary SAVEALMA This command saves the latest almanac in non-volatile memory. The option ONNEW is the default; if a different setting is used, a ONNEW will resume after a reset. SAVECONFIG command must be issued or else Bit 21 in the receiver self-test status word (see Table D-5, Page 196) indicates whether the latest almanac received by the GPS receiver is newer than the almanac saved in non-volatile memory (NVM).
C Commands Summary SAVECONFIG This command saves the user’s present configuration in non-volatile memory. Syntax: SAVECONFIG 120 MiLLennium GPSCard Software Version 4.
C Commands Summary SEND This command is used to send ASCII printable data from the COM1 or COM2 or disk file to a specified communications port. This is a one-time command, therefore the data message must be preceded by the SEND command followed by the key () each time you wish to send data. (Remember to use the MESSAGES command to disable error reporting whenever two GPSCards are connected together via the COM ports.
C Commands Summary SENDHEX This command is like the SEND command but is used to send non-printable characters expressed as hexadecimal pairs.
C Commands Summary SETDGPSID This command is used to enter a station ID. Once set, the receiver will only accept differential corrections from a station whose ID matches the set station ID. It is typically used when a station has data links containing RTCM or RTCA messages from several stations. By entering a specific station ID, the operator can select which station to listen to. Having set a station ID, incoming, RTCM, RTCMA, RTCA, RTCAA, and RTCAB messages will be received from only that station.
C Commands Summary SETHEALTH This command permits you the flexibility to override the broadcast health of a satellite. Under certain conditions and applications, it may be desirable to track and use information from a GPS satellite even though its health has been set bad by the GPS control segment. To SETHEALTH for more than one satellite, the command must be re-issued for each satellite. IMPORTANT: There is usually a reason when the GPS Control Segment sets a satellite to bad health condition.
C Commands Summary SETL1OFFSET The characteristic signal delays introduced by the antenna, coaxial cable and GPSCard RF section will vary from one system configuration to another. These delays are measurable using external test equipment. For applications which involve very precise time transfer, or where ranges are used from multiple receivers, it may be necessary to add an offset to the L1 pseudorange to compensate for these delays.
C Commands Summary SETNAV This command permits entry of one set of navigation waypoints (see Figure C-5). The origin (FROM) and destination (TO) waypoint coordinates entered are considered on the ellipsoidal surface of the current datum (default WGS84). Once SETNAV has been set, you can monitor the navigation calculations and progress by observing the NAVA/B, GPRMB, and GPZTG log messages.
C Figure C-5 Commands Summary Illustration of SETNAV Parameters Reference Description 1 2 3 4 5 6 7 TO, lat-lon X-Track perpendicular reference point Current GPS position A-Track perpendicular reference point X-Track (cross-track) A-Track (along track) Distance and bearing from 3 to 1 MiLLennium GPSCard Software Version 4.
C Commands Summary SETTIMESYNC This command enables or disables time synchronization, which permits two GPSCards in a master/slave relationship to be synchronized to a common external clock for range comparisons. By default, this function is disabled. With SETTIMESYNC enabled, a slave unit is able to interpret injected ($)TM1A/B data messages; for more information, please refer to the comments relating to the ($)TM1A/B special data messages, and the 1PPS signal.
C Commands Summary UNASSIGN This command cancels a previously issued ASSIGN command and the channel reverts to automatic control. If a channel has reached state 4 (PLL), the satellite being tracked will not be dropped when the UNASSIGN command is issued, unless it is below the elevation cutoff angle, and there are healthy satellites above the ecutoff that are not already assigned to other channels.
C Commands Summary UNDULATION This command permits you to either enter a specific geoidal undulation value or use the internal table of geoidal undulations. The separation values only refer to the separation between the WGS84 ellipsoid and the geoid, regardless of the datum chosen, see the PRTKA/B log in Chapter 3 and Appendix D.
C Commands Summary UNFIX This command removes all position constraints invoked with any of the FIX commands (FIX POSITION, FIX HEIGHT, or FIX VELOCITY). Syntax: UNFIX UNLOCKOUT This command allows a satellite which has been previously locked out (LOCKOUT command) to be reinstated in the solution computation. If more than one satellite is to be reinstated, this command must be reissued for each satellite reinstatement.
C Commands Summary UNLOG This command permits you to remove a specific log request from the system. The [port] parameter is optional. If [port] is not specified, it is defaulted to the port that the command was received on. This feature eliminates the need for you to know which port you are communicating on if you want logs to come back on the same port you are sending commands on.
C Commands Summary USERDATUM This command permits entry of customized ellipsoidal datum parameters. Use this command in conjunction with the DATUM command. The default setting is WGS84. Syntax: USERDATUM semi-major Syntax Range Value USERDATUM semi-major min. 6300000.0 max. 6400000.0 min. 290.0 max. 305.0 min. - 2000.0 max. 2000.0 flattening dx,dy,dz rx,ry,rz min. max. -10 10 scale min. max.
C Commands Summary VERSION Use this command to determine the current software version of the GPSCard. The response to the command is logged to the port from which the command originated. VERSION Syntax: VERSION Command VERSION Response Syntax Card type Model # S/N HW Rev SW Rev Date Example: version OEM-3 MILLENRT2 ESN251448497 HW 3-1 SW 4.433/2.03 Feb 18/97 com1> 134 MiLLennium GPSCard Software Version 4.
C Commands Summary WAASCORRECTION WAAS This command allows you to have an affect on how the card handles WAAS corrections. The card will switch automatically to Pseudorange Differential (RTCM or RTCA) or RTK if the appropriate corrections are being received, regardless of the current setting. The ability to incorporate the WAAS corrections into the position solution is not the default mode.
D Logs summary D D LOGS SUMMARY LOGS SUMMARY LOG DESCRIPTIONS ALMA/B Decoded Almanac This log contains the decoded almanac parameters from subframes four and five as received from the satellite with the parity information removed and appropriate scaling applied. Multiple messages are transmitted, one for each SV almanac collected. The Ionospheric Model parameters (IONA) and the UTC Time parameters (UTCA) are also provided, following the last almanac records.
D Logs summary Example: $ALMA,1,3.55577E-003,32768,745,-7.8860E-009,-6.0052951E-002,-1.1824254E+000, 1.67892137E+000,-1.8119E-005,-3.6379E-012,1.45854965E-004,2.65602281E+007, 9.55576E-001,1,0,0*20[CR][LF] ... $ALMA,31,4.90665E-003,32768,745,-8.0460E-009,3.05762855E+000,6.14527459E-001, 1.69958217E+000,6.67572E-006,3.63797E-012,1.45861888E-004,2.65593876E+007, 9.
D Logs summary UTCA FORMAT Structure: $UTCA delta-time Field # 1 2 3 4 5 6 7 8 9 10 11 pct lsop Field type $UTCA pct p1ot data-ref wk #-utc wk #-lset delta-time lsop day #-lset *xx [CR][LF] p1ot data-ref day #-lset *xx wk#-utc wk#-lset [CR][LF] Data Description Log header Polynomial constant term, seconds Polynomial 1st order term, seconds/second UTC data reference time, seconds Week number of UTC reference, weeks Week number for leap sec effect time, weeks Delta time due to leap sec, seconds For u
D Logs summary ALMB ALMB FORMAT: Message ID = 18 Field # 1 (header) Field Type 2 3 4 5 6 7 8 9 10 Sync Checksum Message ID Message byte count Satellite PRN number Eccentricity Almanac ref. time Almanac ref.
D Logs summary UTCB FORMAT: Field # 1 (header) 2 3 4 5 6 7 8 9 140 Message ID = 17 Field Type Sync Checksum Message ID Message byte count Polynomial constant term Polynomial 1st order term UTC data reference time Week number UTC reference Week number for leap sec effect time Delta time due to leap sec For use when leap sec on past Day number for leap sec effect time Message Byte Count = 52 Bytes 3 1 4 4 8 8 4 4 4 4 4 4 Format char char integer integer double double integer integer integer integer inte
D Logs summary BSLA/B Baseline Measurement RTK This log contains the most recent matched baseline representing the vector from the reference station receiver to the remote station receiver. It is expressed in ECEF coordinates with corresponding uncertainties along each axis, and a time tag. The estimated variance of the baseline in ECEF XYZ coordinates is the same as the XYZ position variance.
D Logs summary BSLB Format: Message ID = 59 Message byte count = 100 Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 142 Data Sync Checksum Message ID Message byte count Week number GPS time into the week Number of matched satellites (00-12) Number of matched satellites above RTK mask angle Number of matched satellites above RTK mask angle with both L1 and L2 available ECEF X baseline ECEF Y baseline ECEF Z baseline Standard deviation of X baseline Standard deviation of Y baseline Standard devia
D Logs summary Table D-1 GPSCard Solution Status Value 0 1 2 3 Description Solution computed Insufficient observations No convergence Singular ATPA Matrix Covariance trace exceeds maximum (trace > 1000 m) Test distance exceeded (maximum of 3 rejections if distance > 10 km) Not yet converged from cold start Height or velocity limit exceeded.
D Logs summary CDSA/B Communication and Differential Decode Status The GPSCard maintains a running count of a variety of status indicators of the data link. This log outputs a report of those indicators. Parity and framing errors will occur if poor transmission lines are encountered or if there is an incompatibility in the data protocol. If errors occur, you may need to confirm the bit rate, number of data bits, number of stop bits and parity of both the transmit and receiving ends.
D Logs summary Field # Field type 25 dcsagood DCSA is now obsolete. Data Description 0 Example 26 dcsbfail DCSB is now obsolete. 0 27 dcsbgood DCSB is now obsolete.
D Logs summary CDSB Format: Message ID = 39 Field # Message byte count = 128 Data Bytes Format Units Offset 1 Sync 3 char 0 (header) Checksum 1 char 3 Message ID 4 integer 4 Message byte count 4 integer 8 2 Week number 4 integer weeks 12 3 Time of week 4 integer seconds 16 4 Xon COM1 4 integer 20 5 CTS COM1 4 integer 24 6 Parity errors COM1 4 integer 28 7 Overrun errors COM1 4 integer 32 8 Framing error COM1 4 integer 36 9 Bytes received in CO
D Logs summary CLKA/B Receiver Clock Offset Data This record is used to monitor the state of the receiver time. Its value will depend on the CLOCKADJUST command. If CLOCKADJUST is enabled, then the offset and drift times will approach zero. If not enabled, then the offset will grow at the oscillator drift rate. Disabling CLOCKADJUST and monitoring the CLKA/B log will allow you to determine the error in your GPSCard receiver reference oscillator as compared to the GPS satellite reference.
D Logs summary CLKB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 148 Message ID = 02 Message byte count = 68 Field Type Bytes Sync Checksum Message ID Message byte count Week number Seconds of week Clock offset Clock drift SA Gauss-Markov state StdDev clock offset StdDev clock drift Clock model status 3 1 4 4 4 8 8 8 8 8 8 4 Format char char integer integer integer double double double double double double integer Units weeks seconds seconds seconds per second seconds seconds seconds per second O
D Logs summary CLMA/B Receiver Clock Model The CLMA and CLMB logs contain the current clock-model matrices of the GPSCard. These logs can be both generated and received by a GPSCard. NOTE: Only advanced users should seek to alter the clock model parameters of a GPSCard.
D Logs summary Example: $CLMA,0,0,5.113140990E+010,5.113140990E+010,5.810550069E+003, -1.07377180E+002,-1.41936974E+002,9.744136534E+004, 1.676933050E+003,-8.98776739E+004,1.676933050E+003, 4.750666170E+002,-7.06077622E+002,-8.98776739E+004, -7.06077622E+002,8.
D Logs summary CMR Standard Logs The Compact Measurement Record (CMR) Format, a standard communications protocol used in Real-Time Kinematic (RTK) systems to transfer GPS carrier phase and code observations from a reference station to one or more rover stations. See Chapter 4 for more information on CMR standard logs. MiLLennium GPSCard Software Version 4.
D Logs summary COM1A/B and COM2A/B Pass-Through Logs There are two pass-through logs COM1A/B and COM2A/B, available on MiLLennium GPSCards. The pass-through logging feature enables the GPSCard to redirect any ASCII or binary data that is input at a specified port (COM1 or COM2) to any specified GPSCard port (COM1 or COM2). This capability, in conjunction with the SEND command, can allow the GPSCard to perform bi-directional communications with other devices such as a modem, terminal, or another GPSCard.
D Logs summary DOPA/B Dilution of Precision The dilution of precision data is calculated using the geometry of only those satellites that are currently being tracked and used in the position solution by the GPSCard and updated once every 60 seconds or whenever a change in the constellation occurs. Therefore, the total number of data fields output by the log is variable, depending on the number of SVs tracking. Twelve is the maximum number of SV PRNs contained in the list.
D Logs summary DOPB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 11...
D Logs summary ETSA/B Extended Tracking Status These logs provide channel tracking status information for each of the GPSCard parallel channels. NOTE: This log is intended for status display only; since some of the data elements are not synchronized together, they are not to be used for measurement data. Please use the RGEA/B/D, SATA/B, and SVDA/B logs to obtain synchronized data for post processing analysis.
D Logs summary Example (carriage returns have been added between observations for clarity): $ETSA,850,332087.00,0,24, 7,00082E04,-613.5,54.682,27.617,12301.4,20257359.57,0, 7,00582E0B,-478.1,46.388,0.000,11892.0,20257351.96,13, 5,00082E14,3311.2,35.915,1.037,1224.4,24412632.47,0, 5,00582E1B,2580.4,39.563,0.000,1186.7,24412629.40,13, 9,00082E24,1183.1,53.294,-29.857,7283.8,21498303.67,0, 9,00582E2B,921.9,44.422,0.000,7250.2,21498297.13,13, 2,00082E34,-2405.2,50.824,-20.985,19223.6,22047005.
D Logs summary FRMA/B Framed Raw Navigation Data This message contains the raw framed navigation data. An individual message is sent for each PRN being tracked. The message is updated with each new frame, therefore it is best to log the data with the ‘onnew’ trigger activated.
D Logs summary GGAB Global Position System Fix Data (Binary Format Only) Time, position and fix-related data of the GPS receiver. This binary log is a replica of the NMEA GPGGA ASCII log expressed in binary format with NovAtel header added. Format: Message ID = 27 Field # Data 1 (header) 2 3 4 5 6 7 8 9 10 158 Bytes Format Units Offset Sync Checksum Message ID Message byte count UTC time of position Latitude (DDmm.mm) (+ is North, - is South) Longitude (DDDmm.
D Logs summary GPALM Almanac Data This log outputs raw almanac data for each satellite PRN contained in the broadcast message. A separate record is logged for each PRN, up to a maximum of 32 records. Following a GPSCard reboot, no records will be output until new broadcast message data is received from a satellite. It takes a minimum of 12.5 minutes to collect a complete almanac following GPSCard boot-up. (The almanac reported here has no relationship to the NovAtel $ALMA almanac injection command.
D Logs summary GPGGA Global Position System Fix Data Time, position and fix-related data of the GPS receiver. The information contained in this log is also available in the NovAtel GGAB log in binary format. This log will output all null data fields until the GPSCard has achieved first fix.
D Logs summary GPGLL Geographic Position Latitude and longitude of present vessel position, time of position fix, and status. This log will output all null data fields until the GPSCard has achieved first fix. Structure: $GPGLL Field lat lat dir Structure 1 2 3 4 5 6 $GPGLL lat lat dir lon lon dir utc 7 8 9 data status *xx [CR][LF] lon lon dir utc data status Field Description Log header Latitude (DDmm.mm) Latitude direction (N = North, S = South) Longitude (DDDmm.
D Logs summary GPGRS GPS Range Residuals for Each Satellite Range residuals can be computed in two ways, and this log reports those residuals. Under mode 0, residuals output in this log are used to update the position solution output in the GPGGA message. Under mode 1, the residuals are re-computed after the position solution in the GPGGA message is computed. The GPSCard computes range residuals in mode 1.
D Logs summary GPGSA GPS GPS DOP and Active Satellites receiver operating mode, satellites used for navigation and DOP values.
D Logs summary GPGST Pseudorange Measurement Noise Statistics Pseudorange measurement noise statistics are translated in the position domain in order to give statistical measures of the quality of the position solution.
D Logs summary GPGSV GPS Satellites in View Number of SVs in view, PRN numbers, elevation, azimuth and SNR value. Four satellites maximum per message. When required, additional satellite data sent in second or third message. Total number of messages being transmitted and the current message being transmitted are indicated in the first two fields. NOTE 1: Satellite information may require the transmission of multiple messages. The first field specifies the total number of messages, minimum value 1.
D Logs summary GPRMB Navigation Information Navigation data from present position to a destination waypoint. The destination is set active by the GPSCard SETNAV command. If SETNAV has been set, a command to log either GPRMB or GPRMC will cause both logs to output data.
D Logs summary GPRMC GPS Specific Information Time, date, position, track made good and speed data provided by the GPS navigation receiver. RMC and RMB are the recommended minimum navigation data to be provided by a GPS receiver. This log will output all null data fields until the GPSCard has achieved first fix.
D Logs summary GPVTG Track Made Good And Ground Speed The track made good and speed relative to the ground. Structure: $GPVTG N track true speed km Field Structure 1 2 3 4 $GPVTG track true T track mag 5 6 7 8 9 10 11 M speed Kn N speed Km K *xx [CR][LF] T track mag K *xx M speed Km [CR][LF] Field Description Symbol Example x.x T x.x $GPVTG 24.168 T 24.
D Logs summary GPZDA UTC Time and Date This log will output all null data fields until the GPSCard has achieved first fix. Structure: $GPZDA utc day month NULL NULL *xx [CR][LF] Field Structure 1 2 3 4 5 6 7 $GPZDA utc day month year null null 8 9 *xx [CR][LF] year Field Description Symbol Log header UTC time Day, 01 to 31 Month, 01 to 12 Year Local zone description - not available Local zone minutes description - not available Checksum Sentence terminator 1 hhmmss.
D Logs summary GPZTG UTC & Time to Destination Waypoint This log reports time to destination waypoint. Waypoint is set using the GPSCard SETNAV command. If destination waypoint has not been set with SETNAV, time-to-go and destination waypoint ID will be null. This log will output all null data fields until the GPSCard has achieved first fix.
D Logs summary MKPA/B Mark Position This log contains the estimated position of the antenna at detected mark impulse. It uses the last valid position and velocities to extrapolate the position at time of mark. Refer to the GPSCard Installation and Operating Manual Appendix for Mark Input pulse specifications. The latched time of mark impulse is in GPS weeks and seconds into the week. The resolution of the latched time is 49 ns.
D Logs summary MKTA/B Time of Mark Input This log contains the time of the detected Mark Input pulse leading edge as detected at the Mark Input I/O port. The resolution of this measurement is 49ns. Refer to the GPSCard Installation and Operating Manual Appendix for the Mark Input pulse specifications.
D Logs summary NAVA/B Waypoint Navigation Data This log reports the status of your waypoint navigation progress. It is used in conjunction with the command. SETNAV REMEMBER: The SETNAV command must be enabled before valid data will be reported from this log.
D Logs summary NAVB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 174 Message ID = 08 Data Sync Checksum Message ID Message byte count Week number Seconds of week Distance Bearing Along track Xtrack ETA week ETA seconds NAV status where 0 = good 1 = no velocity 2 = bad navigation Solution status Message byte count = 76 Bytes Format 3 1 4 4 4 8 8 8 8 8 4 8 4 char char integer integer integer double double double double double integer double integer 4 integer Units weeks seconds meters degree
D Logs summary Figure D-1 Example of Navigation Parameters A = FROM lat-lon B = TO lat-lon AB = Great circle line drawn between FROM A lat-lon and TO B lat-lon AC = Track offset from A to C BD = Track offset from B to D CD = Offset track to steer (parallel to AB) F = Current GPS position FD = Current distance and bearing from F to D E = Xtrack perpendicular reference point EF = Xtrack error from E to F (perpendicular to CD) FG = Along track from F to G (perpendicular to BD) AB - True bearing = 70° AB - Magn
D Logs summary PAVA/B Position Averaging Status These logs are meant to be used in conjunction with the POSAVE command. If the POSAVE command has not been issued, all fields in the PAVA/B logs except week and seconds will be zero. However, when position averaging is underway, the various fields contain the parameters being used in the position averaging process. The log trigger ONCHANGED is recommended, but ONTIME can also be used. See the description of the POSAVE command, Page 109. See also Section A.
D Logs summary PAVB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 Message ID = 50 Message byte count = 80 Data Sync Checksum Message ID Message byte count GPS week number GPS seconds into the week Average WGS84 latitude Average WGS84 longitude Average height above sea level Estimated standard deviation of the average latitude Estimated standard deviation of the average longitude Estimated standard deviation of the average height Elapsed time of averaging Number of samples in the average Bytes Form
D Logs summary POSA/B Computed Position This log will contain the last valid position and time calculated referenced to the GPSAntenna phase centre. The position is in geographic coordinates in degrees based on your specified datum (default is WGS84). The height is referenced to mean sea level. The receiver time is in GPS weeks and seconds into the week. The estimated standard deviations of the solution and current filter status are also included. See also Section A.3.2 Pseudorange Algorithms, Page 67.
D Logs summary PRTKA/B Computed Position (RTK) This log contains the best available position computed by the receiver, along with three status flags. In addition, it reports other status indicators, including differential lag, which is useful in predicting anomalous behavior brought about by outages in differential corrections. This log replaces the P20A log; it is similar, but adds extended status information.
D Logs summary Example: $PRTKA,872,174963.00,1.000,8,7,7,51.11358042429, -114.04358006710,1059.4105, -16.2617,61,0.0096,0.0100,0.
D Logs summary PVAA/B XYZ Position, Velocity and Acceleration The PVAA/B logs contain the receiver’s latest computed position, velocity and acceleration in ECEF coordinates. The position, velocity and acceleration status fields indicate whether or not the corresponding data are valid. This command supports INS (Inertial Navigation System) integration. PVA logs can be injected into the receiver from an INS.
D Logs summary PVAB Format: Field # 1 (header) Message ID = 49 Field Type Message byte count = 108 Bytes Format 2 3 4 5 6 7 8 9 10 Sync Checksum Message ID Message byte count GPS week number GPS time of week Position vector along X-axis Position vector along Y-axis Position vector along Z-axis Velocity vector along X-axis Velocity vector along Y-axis Velocity vector along Z-axis Acceleration vector along X-axis 3 1 4 4 4 8 8 8 8 8 8 8 8 char char integer integer integer double double double double d
D Logs summary PXYA/B Computed Cartesian Coordinate Position This log contains the last valid position, expressed in Cartesian x-y-z space coordinates, relative to the center of the Earth. The positions expressed in this log are always relative to WGS84, regardless of the setting of the DATUM or USERDATUM command. See Figure D-2, Page 185 for a definition of the coordinates.
D Logs summary PXYB Format: Message ID = 26 Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 12 Message byte count = 88 Data Bytes Sync Checksum Message ID Message byte count Week number Seconds of week x y z StdDev of x StdDev of y StdDev of z Solution status Fix status 1 3 1 4 4 4 8 8 8 8 8 8 8 4 4 Differential lag, age of differential corrections 1 8 Format char char integer integer integer double double double double double double double integer integer double Units weeks seconds meters meters m
D Logs summary Figure D-2 The WGS84 ECEF Coordinate System MiLLennium GPSCard Software Version 4.
D Logs summary RALA/B Raw Almanac Almanac and health data are contained in subframes four and five of the satellite broadcast message. Subframe four contains information for SVs 25-32, as well as ionospheric, UTC and SV configuration data. Subframe five contains information for SVS 1-24. Subframes four and five each contain 25 pages of data, and each page contains ten 30-bit words of information as transmitted from the satellite.
D Logs summary RASA/B Raw Almanac Set This is a single log for the entire Almanac data set. Only a complete log will be set so you do not have to worry about ephemeris data imitating an Almanac.
D Logs summary RASB Format: Field # 1 2 3 4 5 6 7 8 9 10... Message ID = 66 Data Bytes Sync Checksum Message ID Message byte count Week data received Approximate seconds into week data received Almanac reference week Almanac reference seconds PRN of satellite from which data originated Number of subframes to follow Subframe number Page number Next PRN offset = 40 + (obs *32) Note: Variable Length = 40 + (n * 32).
D Logs summary RBTA/B Satellite Broadcast Data: Raw Bits This message contains the satellite broadcast data in raw bits before FEC (forward error correction) decoding or any other processing. An individual message is sent for each PRN being tracked. For a given satellite, the message number increments by one each time a new message is generated. This data matches the SBTA/B data if the message numbers are equal. The data must be logged with the ’onnew’ trigger activated to prevent loss of data.
D Logs summary RCCA Receiver Configuration This log outputs a list of all current GPSCard command settings. Observing this log is a good way to monitor the GPSCard configuration settings. See Chapter 2, Page 24 for the RCCA default list. 190 MiLLennium GPSCard Software Version 4.
D Logs summary RCSA/B Receiver Status The RCSA log will always output four records: one for VERSION, one for receiver CHANNELS, one for receiver CPU IDLE time, and one indicating receiver self-test STATUS. However, RCSB will embed the same information in a single record. Together, the RVSA/B and VERA/B logs supersede the RCSA/B logs. In other word this log is soon to be obsolete and eventually will be no longer supported. It is recommended then that you use the RVSA/B and VERA/B logs.
D Logs summary REPA/B Raw Ephemeris REPA This log contains the raw Binary information for subframes one, two and three from the satellite with the parity information removed. Each subframe is 240 bits long (10 words - 24 bits each) and the log contains a total 720 bits (90 bytes) of information (240 bits x 3 subframes). This information is preceded by the PRN number of the satellite from which it originated. This message will not be generated unless all 10 words from all 3 frames have passed parity.
D Logs summary RGEA/B/D Channel Range Measurements RGEA/B/D contain the channel range measurements for the currently observed satellites. The RGED message is a compressed form of the RGEB message. When using these logs, please keep in mind the constraints noted along with the description. It is important to ensure that the receiver clock has been set and can be monitored by the bits in the rec-status field. Large jumps in range as well as ADR will occur as the clock is being adjusted.
D Logs summary RGEA Structure: $RGEA prn week seconds # obs rec status psr psr std adr adr std dopp C/No locktime ch-tr-status psr psr std adr adr std dopp C/No locktime ch-tr-status : prn *xx [CR][LF] Field # Field type Data Description 1 2 3 4 5 $RGEA week seconds # obs rec status Log header GPS week number GPS seconds into the week Number of satellite observations with information to follow Receiver self-test status, see Table D-5,, Page 196.
D Logs summary RGEB Format: Message ID = 32 Field # 1 (header) Message byte count = 32 + (obs x 44) Data Bytes Format 2 3 4 5 6 7 8 9 10 11 12 Sync Checksum Message ID Message byte count Week number Seconds of week Number of observations (obs) Receiver self-test status PRN Pseudorange StdDev pseudorange Carrier phase - accumulated Doppler range, cycles StdDev - accumulated Doppler range, cycles Doppler frequency C/N0 3 1 4 4 4 8 4 4 4 8 4 8 4 4 4 char char integer integer integer double integer i
D Logs summary Table D-5 Receiver Self-Test Status Codes N7 N 6 27 26 25 N5 24 23 22 21 N4 20 19 18 17 N 3 16 15 14 13 N2 12 11 10 9 N1 8 7 6 5 N 0 4 3 2 1 0 <- Nibble <- Number Bit Description lsb ANTENNA = 0 1 L1 PLL Range Values Hex Value 1 = good, 0 = bad 00000001 1 = good, 0 = bad 00000002 2 RAM 1 = good, 0 = bad 00000004 3 ROM 1 = good, 0 = bad 00000008 4 DSP 1 = good, 0 = bad 00000010 5 L1 AGC 1 = good, 0 = bad 00000020 6 COM1 1 = good, 0 = bad 000000
D Logs summary Notes on Table D-5: 1. Bit 3: On OEM GPSCards, “ROM” includes all forms of non-volatile memory. 2. Bits 12-15: Flag is reset to 0 five minutes after the last overrun/overload condition has occurred. GPSCard example: All OK = 0000 0000 0000 1010 0000 0000 1111 1111 (binary) = 000A00FF (hexadecimal); using a VCTCXO oscillator. RECEIVER STATUS - DETAILED BIT DESCRIPTIONS OF SELF-TEST Bit 0 Antenna 1 This bit will be set to 1 if the antenna connection is not drawing excessive current.
D Logs summary 1 If set to 1, the receiver has detected a high power signal causing interference. When this happens, the receiver goes into a special anti-jamming mode where it re-maps the A/D decode values as well as special L1AGC feedback control. These adjustments help to minimize the loss that will occur in the presence of a jamming signal. You should monitor this bit, and if set to 1, do your best to remedy the cause of the jamming signal.
D Logs summary Bit 20 OCXOPLL 1 When an external oscillator is connected and the OCXOPLL bit passes self-test, the bit will be set to 1. 0 If no external oscillator is detected or a fault is detected in the OCXOPLL bit, this bit is set to 0. Bit 21 Saved Almanac Needs Update 1 When the almanac received is newer than the one currently stored in NVM (non-volatile memory), the bit will be set to 1.
D Logs summary 4 ADR (Accumulated Doppler Range) is calculated as follows: ADR_ROLLS = ( -RGED_PSR / WAVELENGTH - RGED_ADR) / MAX_VALUE Round to the closest integer IF (ADR_ROLLS ≤ -0.5) ADR_ROLLS = ADR_ROLLS - 0.5 ELSE ADR_ROLLS = ADR_ROLLS + 0.5 At this point integerise ADR_ROLLS CORRECTED_ADR = RGED_ADR + (MAX_VALUE * ADR_ROLLS) where: ADR has units of cycles WAVELENGTH = 0.1902936727984 for L1 WAVELENGTH = 0.2442102134246 for L2 MAX_VALUE = 8388608 5 Code 6 200 RGED 0 0.000 to 0.050 1 0.
D Logs summary Table D-7 Channel Tracking Status N 7 31 30 29 N 6 28 27 26 25 N 5 24 23 22 21 N 4 20 19 18 17 N 3 16 15 14 13 N 2 12 11 10 9 N1 8 7 6 5 N0 4 3 2 1 <- <- Nibble Number 0 Bit Description Range Values lsb = 0 1 Tracking state Hex.
D Logs summary RINEX The Receiver-Independent Exchange (RINEX) format is a broadly-accepted, receiver-independent format for storing GPS data. It features a non-proprietary ASCII file format that can be used to combine or process data generated by receivers made by different manufacturers. RINEX was originally developed at the Astronomical Institute of the University of Berne. Version 2, containing the latest major changes, appeared in 1990; subsequently, minor refinements were added in 1993.
D Logs summary RPSA/B Reference Station Position and Health This log contains the ECEF XYZ position of the reference station as received through the RTCA Type 7 or RTCM Type 3 message. It also features a time tag, the health status of the reference station, and the station ID. This information is set at the reference station using the FIX POSITION command.
D Logs summary RTCA Standard Logs The RTCA (Radio Technical Commission for Aviation Services) Standard is being designed to support Differential Global Navigation Satellite System (DGNSS) Special Category I (SCAT-I) precision instrument approaches. The RTCA Standard is in a preliminary state. NovAtel’s current support for this Standard is based on "Minimum Aviation System Performance Standards DGNSS Instrument Approach System: Special Category I (SCAT-I)" dated August 27, 1993 (RTCA/DO-217).
D Logs summary RTKA/B Computed Position - Time Matched RTK This log represents positions that have been computed from time matched reference and remote observations. There is no reference station extrapolation error on these positions but because they are based on buffered measurements, they lag real time by some amount depending on the latency of the data link.
D Logs summary RTKB Format: Message ID = 61 Message byte count = 116 Field # Data 1 (header) Sync Checksum Message ID Message byte count Week number GPS time into the week Number of matched satellites (00-12) Number of matched satellites above RTK mask angle Number of matched satellites above RTK mask angle with both L1 and L2 available Latitude Longitude Height above mean sea level Undulation Datum ID Standard deviation of latitude Standard deviation of longitude Standard deviation of height Solution
D Logs summary RTKOA/B RTK Solution Parameters RTK This is the “RTK output” log, and it contains miscellaneous information regarding the RTK solution. It is based on the matched update. Note that the length of the log messages will vary depending on the number of matched satellites in the solution, a quantity represented by #sv in the field numbers.
D Logs summary Example: $RTKOA,929,237639.00,1,8,8,8,8,0,4,1,0.000006136,0.000003797, -0.000006287,0.000003797,0.000013211,-0.000007043,-0.000006287, -0.000007043,0.000018575,3.2209,-3.0537, -1.2024,0.0183,0.0138,0.0124,0,0.0000,1,7, 21,6,-0.001199,23,6,0.005461,31,6,0.009608,9,6,0.001963, 15,6,0.000208,29,6,-0.005643,25,6,-0.
D Logs summary Table D-8 Ambiguity Types Ambiguity Type 0 1 2 3 4 5 6 7 8 9 10 Definition L1 only floating Wide lane fixed integer Reserved Narrow lane floating Iono–free floating Reserved Narrow lane fixed integer Iono–free fixed discrete L1 only fixed integer Reserved Undefined type Higher numbers are reserved for future use Table D-9 Searcher Status Searcher Status Definition 0 1 2 3 4 No search requested Searcher buffering measurements Currently searching Search decision made Hand-off to L1 and L2
D Logs summary RVSA/B Receiver Status This log conveys various status parameters of the receiver system. If the system is a multiple-GPSCard unit with a master card, certain parameters are repeated for each individual GPSCard. If the system is composed of only one GPSCard, then only the parameters for that unit are listed. Together, the RVSA/B and VERA/B logs supersede the RCSA/B logs.
D Logs summary RVSB Format: Message ID = 56 Field # 1 (header) 2 3 4 5 6 7 8 9 8 & 9 are repeated for each card NOTE: Data Message byte count = 28 + (8 x number of cards) Bytes Sync 3 Checksum 1 Message ID 4 Message byte count 4 Week number 4 Seconds of week 8 Number of satellite channels 1 Number of signal channels 1 Number of cards 1 Reserved 1 CPU idle time, percent 4 Self-test status 4 Next Card offset = 28 + (8 x card number) Format char char integer integer integer double char char char byte
D Logs summary SATA/B Satellite Specific Data This log provides satellite specific data for satellites actually being tracked. The record length is variable and depends on the number of satellites. Each satellite being tracked has a reject code indicating whether it is used in the solution, or the reason for its rejection from the solution. The reject value of 0 indicates the observation is being used in the position solution.
D Logs summary SATB Format: Message ID =12 Field # Message byte count = 32 + (obs*32) Data Bytes Format Units Offset 1 Sync 3 char 0 (header) Checksum 1 char 3 Message ID 4 integer 4 Message byte count 4 integer 8 2 Week number 4 integer weeks 12 3 Seconds of week 8 double seconds 16 4 Solution status 4 integer 24 5 Number of observations (obs) 4 integer 28 6 PRN 4 integer 32 7 Azimuth 8 double degrees 36 8 Elevation 8 double degrees 44 9 R
D Logs summary SBTA/B SATELLITE BROADCAST DATA: RAW SYMBOLS This message contains the satellite broadcast data in raw symbols before FEC decoding or any other processing. An individual message is sent for each PRN being tracked. For a given satellite, the message number increments by one each time a new message is generated. This data matches the RBTA/B data if the message numbers are equal. The data must be logged with the ’onnew’ trigger activated to prevent loss of data.
D Logs summary SPHA/B Speed and Direction Over Ground This log provides the actual speed and direction of motion of the GPSCard antenna over ground, at the time of measurement, and is updated up to 10 times per second. It should be noted that the GPSCard does not determine the direction a vessel, craft, or vehicle is pointed (heading), but rather the direction of motion of the GPS antenna relative to ground.
D Logs summary SVDA/B SV Position in ECEF XYZ Coordinates with Corrections When combined with a RGEA/B/D log, this data set contains all of the decoded satellite information necessary to compute the solution: satellite coordinates (ECEF WGS84), satellite clock correction, ionospheric corrections (from broadcast model), tropospheric corrections (Hopfield model), decoded differential correction used and range weight standard deviation. The corrections are to be added to the pseudoranges.
D Logs summary SVDB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 12 13 14 15...
D Logs summary TM1A/B Time of 1PPS This log provides the time of the GPSCard 1PPS, normally high, active low pulse (1 millisecond), where falling edge is reference, in GPS week number and seconds into the week. The TM1A/B log follows a 1PPS pulse. It also includes the receiver clock offset, the standard deviation of the receiver clock offset and clock model status. This log will output at a maximum rate of 1 Hz.
D Logs summary VERA/B Receiver Hardware and Software Version Numbers This log contains the current hardware type and software version number for the GPSCard. Together with the RVSA/B log, it supersedes the RCSA/B log. VERA Structure: $VERA Field # week seconds version Field type *xx [CR][LF] Data Description Example 1 2 3 4 $VERA week seconds version Log header GPS week number GPS seconds into the week.
D Logs summary VLHA/B Velocity, Latency, and Direction over Ground This log is similar to the SPHA/B message. As in the SPHA/B messages the actual speed and direction of the GPSCard antenna over ground is provided. The VLHA/B differs in that it provides a measure of the latency in the velocity time tag and a new velocity status word which gives the user more velocity quality information. The velocity status indicates varying degrees of velocity quality.
D Logs summary VLHB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 Message ID = 34 Message byte count = 72 Data Bytes Sync Checksum Message ID Message byte count Week number Seconds of week Latency Age Horizontal speed Track over ground (TOG) Vertical speed Solution status Velocity status 3 1 4 4 4 8 8 8 8 8 8 4 4 Format char char integer integer integer double double double double double double integer integer Units weeks seconds metres per second seconds metres per second degrees metres per seco
D Logs summary WALA/B WAAS Almanac WAAS Structure: $WALA week seconds prn data ID health pos X pos Y pos Z vel X vel Y vel Z Field # Field type WAAS week WAAS seconds Data Description Example 1 $WALA Log header $WALA 2 week GPS week number 981 3 seconds GPS seconds into the week 447490.
D Logs summary WALB Format: Message ID = 81 Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 12 13 14 Message byte count = 92 Data Bytes Sync Checksum Message ID Message byte count Week number Seconds of week WAAS week number WAAS seconds of week WAAS satellite PRN number WAAS signal specification version WAAS satellite health Position x coordinate of WAAS satellite Position y coordinate of WAAS satellite Position z coordinate of WAAS satellite Velocity x coordinate of WAAS satellite Velocity y coordinate o
D Logs summary WRCA/B Wide Band Range Correction (Grouped Format) This message contains the wide band range correction data. A correction is generated for each PRN being tracked and these group together into a single log. Internally, the correction for each satellite is updated asynchronously at a 1 Hz rate. Therefore, logging this message at a rate higher than 1 Hz will result in duplicate data being output.
E Comparison Of RT-2 And RT-20 E COMPARISON OF RT-2 AND RT-20 E COMPARISON OF RT-2 AND RT-20 E.1 RT-2 & RT-20 PERFORMANCE RT-2 and RT-20 are real-time kinematic software products developed by NovAtel. They can only be used in conjunction with NovAtel GPS receivers.
E Comparison Of RT-2 And RT-20 RT-2 Performance The RT-2 software provides the accuracies shown in Table E-3 & Figure E-1 (static mode) and Table E-4 & Figure E-2 (kinematic mode) for “typical” multipath, ionospheric, tropospheric, and ephemeris errors, where “typical” is described as follows: • A typical multipath environment would provide no carrier-phase double-difference multipath errors greater than 2 cm or pseudorange double-difference multipath errors greater than 2 m on satellites at 11° elevation
E Comparison Of RT-2 And RT-20 Figure E-1 Typical RT-2 Horizontal Convergence - Static Mode 1.4 1.2 Baselines CEP(meters) 1 0.1 km 15 km 0.8 25 km 50 km 1500 1800 0.6 0.4 0.2 0 0 300 600 900 1200 2100 2400 2700 3000 3300 3000 3300 Seconds of Convergence Figure E-2 Typical RT-2 Horizontal Convergence - Kinematic Mode 1.4 1.2 Baselines CEP(meters) 1 0.1 km 15 km 25 km 50 km 0.8 0.6 0.4 0.
E Comparison Of RT-2 And RT-20 For baselines under 30 km long, the RT-2 solution shows two pronounced steps in accuracy convergence; these correspond to the single-point solution switching to the floating ambiguity solution which in turn switches to the narrow lane solution. If you were monitoring this using NovAtel’s GPSolution program, the convergence sequence might look something like what is shown in Figure E-3.
E Comparison Of RT-2 And RT-20 Table E-6 RT-20 Performance Tracking Time (sec) Mode 1 Data Delay (sec) Distance (km) 1 - 180 180 - 3000 > 3000 Static Static Static 0 0 0 1 1 1 1 - 600 600 - 3000 > 3000 Kinematic Kinematic Kinematic 0 0 0 1 1 1 Either Either Either Either 0-2 2-7 7 - 30 > 30 1 1 1 1 Either Either Either 0 0 0 0 - 10 10 - 20 20 - 50 1 2 3 Accuracy (CEP) 100 to 25 cm 25 to 5 cm 5 cm or less 100 to 25 cm 25 to 5 cm 2 5 cm or less +1 cm/sec +2 cm/sec +5 cm/sec 2 pseudorang
E Comparison Of RT-2 And RT-20 Figure E-6 Typical RT-20 Convergence - Kinematic Mode 1.4 Baselines 1.2 0.1 km 15 km CEP(meters) 1 25 km 50 km 1500 1800 0.8 0.6 0.4 0.2 0 0 300 600 900 1200 2100 2400 2700 3000 3300 Seconds of Convergence Figure E-7 shows the performance of the RT-20 system running with RTCM59 corrections received at a 1/2 Hz rate. Figure E-7 RT-20 Steady State Performance 230 MiLLennium GPSCard Software Version 4.
E Comparison Of RT-2 And RT-20 E.2 PERFORMANCE CONSIDERATIONS When referring to the “performance” of RTK software, two factors are introduced: 1. Baseline length: the position estimate becomes less precise as the baseline length increases. Note that the baseline length is the distance between the phase centres of the two antennas. Identifying the exact position of your antenna’s phase centre is essential; this information is typically supplied by the antenna’s manufacturer or vendor.
E Comparison Of RT-2 And RT-20 and reference model information is lost. The timeout threshold for RTK differential corrections is 30 seconds, but for Type 1 pseudorange corrections, the timeout is 60 seconds. Therefore, when the RT-20 can no longer function because of this timeout, the pseudorange filter can produce differential positions for an additional 30 seconds (provided RTCM Type 1 messages were transmitted along with the Type 59 messages) before the system reverts to single point positioning.
F Standards and References F STANDARDS AND REFERENCES F STANDARDS AND REFERENCES RTCM STANDARDS REFERENCE For detailed specifications of RTCM, refer to RTCM SC104 Version 2.1 of "RTCM Recommended Standards For Differential NAVSTAR GPS Service", January 3, 1994 Radio Technical Commission for Maritime Services 655 15th Street NW, Suite 300 Washington, D.C. 20005 U.S.A. Telephone: 202-639-4006 Fax: 202-347-8540 Website: http://www.navcen.uscg.mil/dgps/dgeninfo/RTCM104.
G Geodetic Datums G GEODETIC DATUMS G GEODETIC DATUMS The following tables contain the internal ellipsoid parameters and transformation parameters used in the GPSCard. The values contained in these tables were derived from the following DMA technical reports: 1. TR 8350.2 Department of Defence World Geodetic System 1984 and Relationships with Local Geodetic Systems - Revised March 1, 1988. 2. TR 8350.
G Geodetic Datums Table G-2 Transformation Parameters (Local Geodetic to WGS84) 17 GRB36 375 -111 431 Great Britain 1936 (Ordinance Survey) Airy 1830 18 GUAM -100 -248 259 Guam 1963 (Guam Island) Clarke 1866 19 HAWAII 89 -279 -183 Hawaiian Hawaii (Old) International 1924 20 KAUAI 45 -290 -172 Hawaiian Kauai (Old) International 1924 21 MAUI 65 -290 -190 Hawaiian Maui (Old) International 1924 22 OAHU 56 -284 -181 Hawaiian Oahu (Old) International 1924 23 HERAT -333
H Some Common Unit Conversions H SOME COMMON UNIT CONVERSIONS H SOME COMMON UNIT CONVERSIONS Section H.1 to H.4 list commonly used equivalents between the SI (Système Internationale) units of weights and measures used in the metric system, and those used in the imperial system. A complete list of hexadecimal values with their binary equivalents is given in Section H.5 while an example of the conversion from GPS time of week to calendar day is shown in Section H.6. H.1 DISTANCE H.
H Some Common Unit Conversions H.6 GPS TIME OF WEEK TO CALENDAR DAY (EXAMPLE) 511200 seconds Day 511200 / 86400 seconds per day = 5.916666667 days Hour .916666667 x 86400 / 3600 seconds per hour Minute .000 x 3600 / 60 seconds per minute Second .000 x 60 = 22.0000 hours = 0.000 minutes = 0.00 seconds Day 5 (Thursday) + 22 hours, 0 minutes, 0 seconds into Friday. H.6.1 Calendar Date to GPS Time (e.g.
I Information Messages INFORMATION MESSAGES I INFORMATION MESSAGES I TYPE 1 INFORMATION MESSAGES To date, the only Type 1 messages are the !ERRA and the !MSGA logs. !ERRA !ERRA Field # 1 2 3 4 5 6 7 type severity error string Field type !ERRA type severity error string opt. description *xx [CR][LF] opt.
I Information Messages Table I-2 Type 1 !MSGA Types Log type 1000 1001 1002+ Message String Unknown MSGA Type Authorization Code Is Time Limited Reserved For Future Use TYPE 2 INFORMATION MESSAGES The following is a list of information messages which are generated by the Command Interpreter in response to a user’s input. This list is not necessarily complete, but it is the most accurate one available at the time of publication. It is intended to be a trouble-shooting tool.
I Information Messages Invalid Channel Number Invalid Coarse Modulus Field Invalid Command CRC Invalid Command Name Invalid Command Option Invalid Coordinates Invalid Datatype Invalid Datum Offset Invalid DATUM Option Invalid Datum Rotation Invalid Degree Field Invalid DGPS time-out value Invalid Doppler Invalid Doppler Window Invalid DTR choice Invalid DTR Toggle Option Invalid DTR Toggle Setup Time (0-1000) Invalid DTR Toggle Terminate Time (0-1000) Invalid DYNAMICS Option Invalid Echo Option Invalid Elev
I Information Messages Invalid Parity Option Invalid Port Invalid Port number Invalid PPS Modulus Field Invalid RINEX Option Invalid RTCA option Invalid RTCA station Name (\XXXX\) Invalid RTCM Bit Rule Invalid RTCM station Name (0..
J Listing Of Tables J LISTING OF TABLES J LISTING OF TABLES This section is provided for ease of reference.
J Listing Of Tables Table 1-1 GPSCard Pseudorange Differential Initialization Summary Reference Station Remote Station Required: Required: FIX POSITION lat lon hgt id (health) LOG port DATATYPE ontime 5 ACCEPT port DATATYPE Recommended Options: Recommended Options: LOG DATATYPES (binary): ACCEPT DATATYPES (binary): RTCMB RTCAB RTCM RTCA RTCM RTCA LOG DATATYPES (acii): ACCEPT COMMANDS (ascii): RTCMA RTCAA RTCMA RTCAA Related Commands/Logs: Related Commands/Logs: RTCMRULE DATUM POSA/B VLHA/B C
J Listing Of Tables 1 Intended for advanced users of GPS onl GENERAL RECEIVER CONTROL AND STATUS Commands Descriptions $ALMA Download almanac data file CRESET DYNAMICS Reset receiver to factory default Set correlator tracking bandwidth HELP On-line command help RESET Performs a hardware reset (OEM only) SAVEALMA Saves the latest almanac in NVM SAVECONFIG $TM1A Saves current configuration (OEM only) Injects receiver time of 1PPS VERSION Software/hardware information POSITION, PARAMETERS, AN
J Listing Of Tables SATELLITE TRACKING AND CHANNEL CONTROL Commands Descriptions $ALMA ASSIGN Download almanac data file Satellite channel assignment CONFIG Switches the channel configuration of the GPSCard DYNAMICS FIX VELOCITY Sets correlator tracking bandwidth Aids high velocity reacquisition RESETHEALTH SETHEALTH Reset PRN health Overrides broadcast satellite health WAYPOINT NAVIGATION Commands Descriptions MAGVAR Magnetic variation correction SETNAV Waypoint input DIFFERENTIAL REFERENC
J Listing Of Tables Table 2-2 GPSCard Command Summary Command Description Syntax $ALMA Injects almanac (follows NovAtel ASCII log format) $IONA Injects ionospheric refraction corrections (follows NovAtel ASCII log format) $PVAA Injects latest computed position, velocity and acceleration (follows NovAtel ASCII log format) $REPA Injects raw GPS ephemeris data (follows NovAtel ASCII log format) $RTCA Injects RTCA format DGPS corrections in ASCII (Type 1) (follows NovAtel ASCII log format) $RT
J Listing Of Tables RTCM16T Enter an ASCII text message to be sent out in the RTCM data stream rtcm16t ascii message RTCMRULE Set variations of the RTCM bit rule rtcmrule rule RTKMODE Set up the RTK mode rrtkmode argument, data range SAVEALMA Save the latest almanac in non-volatile memory savealma option SAVECONFIG Save current configuration in non-volatile memory (OEM only) saveconfig SEND Send an ASCII message to any of the communications ports send port ascii-message SENDHEX Sends non
J Listing Of Tables Table 3-1 Logs By Function Table COMMUNICATIONS, CONTROL AND STATUS Descriptions Logs CDSA/B COM1A/B COM port communications status Log data from COM1 COM2A/B Log data from COM2 COMnA/B RCSA/B Pass-through data logs Receiver self-test status RTCM16T RTCM16 NovAtel ASCII format special message RTCM format special message GENERAL RECEIVER CONTROL AND STATUS Descriptions Logs PVAA/B RCCA Receiver’s latest computed position, velocity and acceleration in ECEF coordinates Receiver c
J Listing Of Tables Logs WAYPOINT NAVIGATION Descriptions GPRMB GPRMC NMEA, waypoint status NMEA, navigation information GPVTG NMEA, track made good and speed GPZTG MKPA/B NMEA, time to destination Position at time of mark input NAVA/B POSA/B Navigation waypoint status Position data SPHA/B Speed and course over ground VLHA/B Velocity, latency & direction over ground Logs DIFFERENTIAL REFERENCE STATION Descriptions ALMA/B Current almanac information CDSA/B COM port data transmission statu
J Listing Of Tables CLOCK INFORMATION, STATUS, AND TIME Descriptions Logs CLKA/B Receiver clock offset information 1 CLMA/B GPZDA Current clock-model matrices of the GPSCard NMEA, UTC time and date GPZTG MKTA/B NMEA, UTC and time to waypoint Time of mark input TM1A/B Time of 1PPS Intended for advanced users of GPS only.
J Listing Of Tables Table 4-1 Positioning Modes Reference station: L1 RTCM Type 59N Reference station: L1 RTCA Type 7 Reference station: L1 & L2 RTCM Type 59N Reference station: L1 & L2 RTCA Type 7 Remote station: L1 RT-20 RT-20 RT-20 RT-20 Remote station: L1 & L2 RT-20 RT-20 RT-20 RT-2 Table C-1 Antenna LNA Power Configuration P301: plug connects pins 1&2 ANTENNAPOWER = ON ANTENNAPOWER = OFF internal power connected to LNA internal power cut off from LNA P301: plug connects pins 2&3 P301:
J Listing Of Tables Table D-1 GPSCard Solution Status Value 0 1 2 3 Description Solution computed Insufficient observations No convergence Singular ATPA Matrix Covariance trace exceeds maximum (trace > 1000 m) Test distance exceeded (maximum of 3 rejections if distance > 10 km) Not yet converged from cold start Height or velocity limit exceeded.
J Listing Of Tables Table D-4 RTK Status for Position Type 4 (RT-2) Status Definition 0 1 2 3 4 5 6 7 8 9 10 Narrow lane solution Wide lane derived solution Floating ambiguity solution (converged) Floating ambiguity solution (not yet converged) Modelling reference phase Insufficient observations Variance exceeds limit Residuals too big Delta position too big Negative variance RTK position not computed Higher numbers are reserved for future use Table D-5 Receiver Self-Test Status Codes N7 N 6 27 26 25
J Listing Of Tables Notes on Table D-5: 1. Bit 3: On OEM GPSCards, “ROM” includes all forms of non-volatile memory. 2. Bits 12-15: Flag is reset to 0 five minutes after the last overrun/overload condition has occurred. Table D-6 Range Record Format (RGED only) Data Bit(s) from first to last Length (bits) PRN 1A, 1B Format Scale Factor 0..5 6 integer 1 C/No 2 6..10 5 integer (20+n) dB-Hz Lock time 3 11.
J Listing Of Tables 5 Code RGED 0 0.000 to 0.050 1 0.051 to 0.075 2 0.076 to 0.113 3 0.114 to 0.169 4 0.170 to 0.253 5 0.254 to 0.380 6 0.381 to 0.570 7 0.571 to 0.854 8 0.855 to 1.281 9 1.282 to 2.375 10 2.376 to 4.750 11 4.751 to 9.500 12 9.501 to 19.000 13 19.001 to 38.000 14 38.001 to 76.000 15 76.001 to 152.
J Listing Of Tables Table D-7 is referenced by the ETSA/B, and RGEA/B/D logs.
J Listing Of Tables Table D-8 Ambiguity Types Ambiguity Type Definition 0 L1 only floating 1 Wide lane fixed integer 2 Reserved 3 Narrow lane floating 4 Iono–free floating 5 Reserved 6 Narrow lane fixed integer 7 Iono–free fixed discrete 8 L1 only fixed integer 9 Reserved 10 Undefined type Higher numbers are reserved for future use Table D-9 Searcher Status Searcher Status Definition 0 No search requested 1 Searcher buffering measurements 2 Currently searching 3 Search deci
J Listing Of Tables Table D-11 GPSCard Range Reject Codes Value Description 0 Observations are good 1 Bad satellite health is indicated by ephemeris data 2 Old ephemeris due to data not being updated during last 3 hours 3 Eccentric anomaly error during computation of the satellite’s position 4 True anomaly error during computation of the satellite’s position 5 Satellite coordinate error during computation of the satellite’s position 6 Elevation error due to the satellite being below the cutof
J Listing Of Tables Table E-3 RT-2 Performance: Static Mode Baseline length < 10 km < 10 km < 15 km < 25 km < 35 km < 35 km Time since L2 lock-on with at least 6 satellites above mask angle Horizontal accuracy at the stated time 70 seconds + 1.5 sec/km 5 minutes 4 minutes 7 minutes 10 minutes 30 minutes 2 cm + 0.5 ppm 1 cm + 1 ppm 5 cm 7 cm 35 cm 25 cm Runs meeting the stated accuracy at the stated time 75.0% 75.0% 66.7% 66.7% 66.7% 66.
K GPS Glossary of Terms K K GPS GLOSSARY OF TERMS GPS Glossary of Terms ASCII — A 7 bit wide serial code describing numbers, upper and lower case characters, special and non-printing characters. Address field — for sentences in the NMEA standard, the fixed length field following the beginning sentence delimiter "$" (HEX 24). For NMEA approved sentences, composed of a two character talker identifier and a three character sentence formatter.
K GPS Glossary of Terms Coarse Acquisition (C/A) Code — a spread spectrum direct sequence code that is used primarily by commercial GPS receivers to determine the range to the transmitting GPS satellite. Uses a chip rate of 1.023 MHz. Communication protocol — a method established for message transfer between a talker and a listener which includes the message format and the sequence in which the messages are to be transferred.
K GPS Glossary of Terms Doppler aiding — a signal processing strategy, which uses a measured Doppler shift to help a receiver smoothly track the GPS signal, to allow more precise velocity and position measurement. Double-Difference — a position estimation mechanization which uses observations which are differenced between receiver channels and between the reference and remote receivers.
K GPS Glossary of Terms Geostationary — a satellite orbit along the equator that results in a constant fixed position over a particular reference point on the earth’s surface. (GPS satellites are not geostationary.) Global Positioning System (GPS) — full name NAVSTAR Global Positioning System, a space-based radio positioning system which provides suitably equipped users with accurate position, velocity and time data.
K GPS Glossary of Terms Magnetic heading — heading relative to magnetic north. Magnetic variation — the angle between the magnetic and geographic meridians at any place, expressed in degrees and minutes east or west to indicate the direction of magnetic north from true north. Mask angle — the minimum GPS satellite elevation angle permitted by a particular receiver design. Satellites below this angle will not be used in position solution.
K GPS Glossary of Terms Precise Positioning Service (PPS) — the GPS positioning, velocity, and time service which will be available on a continuous, worldwide basis to users authorized by the U.S. Department of Defence (typically using P-Code). PRN number — a number assigned by the GPS system designers to a given set of pseudorandom codes. Typically, a particular satellite will keep its PRN (and hence its code assignment) indefinitely, or at least for a long period of time.
K GPS Glossary of Terms Selective Availability (SA) — the method used by the United States Department of Defence to control access to the full accuracy achievable by civilian GPS equipment (generally by introducing timing and ephemeris errors). Sequential receiver — a GPS receiver in which the number of satellite signals to be tracked exceeds the number of available hardware channels. Sequential receivers periodically reassign hardware channels to particular satellite signals in a predetermined sequence.
K GPS Glossary of Terms Universal Time Coordinated (UTC) — this time system uses the second-defined true angular rotation of the Earth measured as if the Earth rotated about its Conventional Terrestrial Pole. However, UTC is adjusted only in increments of one second. The time zone of UTC is that of Greenwich Mean Time (GMT). Update rate — the GPS receiver specification which indicates the solution rate provided by the receiver when operating normally. VDOP — Vertical Dilution of Precision.
L GPS Glossary of Acronyms L GPS GLOSSARY OF ACRONYMS L GPS GLOSSARY OF ACRONYMS 1PPS One Pulse Per Second 2D Two Dimensional 2DRMS Twice distance RMS 3D Three Dimensional A/D Analog-to-Digital ADR Accumulated Doppler Range AGC Automatic Gain Control ASCII American Standard Code for Information Interchange BIH Bureau l’International de l’Heure BIST Built-In-Self-Test bps Bits per Second C/A Code Coarse/Acquisition Code CEP Circular Error Probable C/No Carrier to Noise Density Ratio CPU Central Processing
L GPS Glossary of Acronyms LHCP LNA LO lsb Left Hand Circular Polarization Low Noise Amplifier Local Oscillator Least significant bit MET MEDLL MKI MKO MSAS msb msec MSL Multipath Elimination Technology Multipath Estimation Delay Lock Loop Mark In Mark Out Multi-Functional Transport Satellite (MTSAT) based Augmentation System Most significant bit millisecond Mean sea level N. mi.
M Index M INDEX M INDEX Numerics 1PPS 33, 83, 128, 220 2D 97, 263, 268 2D mode 26, 97, 163, 246 2DRMS 270 3D 263–264, 268, 270 3D mode 163 A acceptance 79 accumulated Doppler 55, 194, 200, 256 acquisition 82, 262–263, 265 age of differential corrections 183, 222 alarm 262 almanac 136, 187, 193, 198, 241 data 30, 31, 63, 136, 159, 187, 262 tables 31 ambiguity 71, 72, 74, 117–118, 143, 193, 227, 230, 233, 254–255, 262–265, 267 angle 214, 215 antenna 160, 197, 214 altitude 158, 160 baseline length 214 cab
M Index number 242 state 82, 194, 226 tracking 82, 155, 201, 258 channels 32, 129, 155, 191, 210, 264, 266–268 channels (number of) 191 chatter 31, 44 checksum 24, 33, 35, 47, 50, 51, 56, 191, 214, 215, 241, 262, 264, 266 clock 33, 37, 42, 53, 56, 59, 63, 65, 67–72, 83, 94–98, 128, 147, 193, 197, 218, 220, 241, 263–264, 267 drift 53, 83, 147 rate 83 frequency error 82 model status 147, 220 offset 37, 68, 147, 153, 172, 220, 267 CMR 17, 18, 45, 55, 79, 80, 144, 145 com buffers 198 port 31, 33, 46, 47, 51, 79
M Index cut-off 88 angle 93 ellipsoid 19, 32, 52, 117, 126, 130, 133, 176, 181, 205, 236, 265, 268, 269 ellipsoidal datum 133 ephemerides 62, 63 ephemeris 32, 46, 51, 55, 63, 68, 70, 90, 187, 192, 228, 233, 268 error message 43, 79, 108 errors 17, 24, 65, 74, 83, 94, 98, 193, 198, 228, 233, 263, 265, 266 external oscillator 33, 94, 96 F factory default 23, 87, 101, 110 FIFO 84, 270 frequency 25, 27, 28, 34, 45, 48, 56, 69, 71, 72, 76, 82, 94, 96, 100, 155, 194, 195, 199, 201, 227, 233, 241, 242, 243, 245,
M Index errors 227 K kinematic 20, 36, 58, 66, 71, 76, 118, 232, 265, 271 L latched time 171 latency 17, 20, 36, 53, 67, 72, 179, 205, 222, 230, 234, 245, 265 latitude 62, 71, 98, 117, 158, 160, 161, 167, 178, 263–266 L-band 63 LNA 81, 197 lockout satellite 104 locktime 88, 194 longitude 62, 71, 98, 117, 158, 160, 161, 167, 171, 178, 263–266 M magnetic variation 106, 107, 167, 173, 266 mask angle 141, 142, 179, 180, 205, 214, 215, 228, 261, 266 master control station 63, 263 mean sea level 19, 62, 97, 11
M Index polarity 73 poor reception 75 port 242 position constraints 131 processing 50, 63, 64, 66, 79, 155, 193, 198, 264, 267 propagation 68, 73, 75, 78 pseudorange 36, 50, 53–55, 56, 59, 65–74, 77, 88, 97, 98, 125, 164, 179, 193, 197, 218, 228, 233, 267 measurement 59, 68, 71, 164, 197 pulse 33, 100, 171, 172, 220 R RAM 197 range weight standard deviation 218 raw almanac 159, 186 reacquisition 32, 82, 99, 181 real-time 64, 65, 68, 71, 227, 267 receiver 14, 19, 24, 32, 33, 35, 37, 45, 47, 51–52, 55, 56, 5
M Index station ID 19, 48, 98, 123, 203 subframes 32, 136, 186, 192 SV health 159 T tag 11, 42, 44, 56, 58, 61, 79, 141, 166, 179, 203, 222 TCXO 68 TDOP 153, 263, 265, 268 track made good 167, 168, 263, 268 offset 126, 243 over ground 217, 222 tracking 31, 33, 71, 82, 88, 98, 99, 104, 129, 153, 181, 193, 198, 201, 210, 230, 233, 257, 258, 262, 263, 266 status 193, 194, 266 transformation 236 triangulation 74 trigger 13, 14, 24, 34, 35, 42, 105, 176, 205, 242 trilateration 74 tropospheric corrections 218 tr
OM-20000041 Rev 1 98/11/03
