Software Version 4.45 OM-20000026 Rev 1 MiLLennium GPSCard TM Command Descriptions Manual GPSCard™ Products NovAtel Inc.
Table of Contents TABLE OF CONTENTS TABLE OF CONTENTS 1 Quick Start 1.1 Installation .............................................................................................................................................................. 1 Graphical Interface ......................................................................................................................................... 1 1.2 Data Logging ........................................................................................
Table of Contents 7 RINEX-Standard Commands & Logs 7.1 Commands .............................................................................................................................................................. 46 7.2 Logs ........................................................................................................................................................................ 47 RINEX ..................................................................................................
Table of Contents LOCKOUT ..................................................................................................................................................... 90 LOG ............................................................................................................................................................... 91 MAGVAR ......................................................................................................................................................
Table of Contents RBTA/B .......................................................................................................................................................... 172 RCCA.............................................................................................................................................................. 173 RCSA/B ..........................................................................................................................................................
Table of Contents FIGURES 5-1 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 Pass-Through Log Data ................................................................................................................................................... 31 NAVSTAR Satellite Orbit Arrangement .........................................................................................................................
1 Quick Start 1 QUICK START 1 QUICK START This chapter is dedicated to getting you started. You may wish to carry out Real-Time Kinematic (RTK) positioning, operate in Differential modes or simply log data. Where to get further information is referenced after each of these sections. 1.1 INSTALLATION For more detailed instructions on the installation and set up of your GPSCard please see the accompanying MiLLennium GPSCard Guide to Installation and Operation.
1 Quick Start 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. See the POSA/B log description in Appendix D. 1.
1 Quick Start Example: log com1,posa,ontime,60,1 If the LOG syntax does not include a trigger type, it will be output only once following execution of the LOG command. If trigger type is specified in the LOG syntax, the log will continue to be output based on the trigger specification. Specific logs can be disabled using the UNLOG command, whereas all enabled logs will be disabled by using the UNLOGALL command (see Chapter 2 and Appendix C).
1 Quick Start Further information may be found in Appendix A. Table 1-1, following, is a GPSCard pseudorange differential initialization summary.
1 Quick Start NOTES: Entry of the station ID and health are optional 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). The GPSCard performs all computations based on WGS84 and is defaulted as such, regardless of DATUM command setting.
1 Quick Start 2. • An RTCAOBS message contains reference station satellite observation information, and should be sent once every 1 or 2 seconds. • An RTCAREF message contains reference station position information, and should be sent once every 10 seconds.
1 Quick Start log com1,rtcaref,ontime,10 log com1,rtcaobs,ontime,2 2. At the remote station: accept comn,rtca Example: accept com2,rtca Congratulations! Your RTK system is now in operation! INITIALIZATION FOR RTCM-FORMAT MESSAGING (RT-20 ONLY) Although RT-20 can operate with either RTCA or RTCM-format messaging, the use of RTCA-format messages is recommended (see Chapter 6 for further information on this topic).
1 Quick Start to collect updated ephemeris data as well. A delay of 120 to 130 seconds will typically ensure that the rover stations have collected updated ephemeris. After the delay period is passed, the reference station will begin using new ephemeris data. To enter an ephemeris delay value, you must first enter a numeric placeholder in the DGPS delay field (e.g., 2).
1 Quick Start to generate, process and decode. The RTCA messages are therefore smaller, they have a 24 bit CRC that is much more robust than RTCM messages, and they permit the use of a four-alpha-character station ID. RTCA Standard logs can be received through the COM1 or COM2 port of the rover GPSCard. The remote GPSCard must issue the “ACCEPT port RTCA” command to dedicate a port before it will accept the RTCA data input to that port. The RTCA logs cannot be intermixed with other logs.
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 4. 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 2.2 COMMAND TABLES Table 2-1 lists the commands by function while Table 2-2 is an alphabetical listing of commands. Please see Appendix C for a more detailed description of individual commands which are listed alphabetically.
2 Command Descriptions Table 2-1 Commands By Function Table (continued) SATELLITE TRACKING AND CHANNEL CONTROL Commands Descriptions $ALMA Download almanac data file ASSIGN CONFIG Satellite channel assignment Switches the channel configuration of the GPSCard DYNAMICS Sets correlator tracking bandwidth FIX VELOCITY RESETHEALTH Aids high velocity reacquisition Reset PRN health SETHEALTH Overrides broadcast satellite health WAYPOINT NAVIGATION Commands Descriptions MAGVAR Magnetic variation corr
2 Command Descriptions Table 2-2 GPSCard Command Summary Command Description $ALMA $IONA $PVAA $REPA $RTCA $RTCM $TM1A $UTCA ACCEPT ANTENNAPOWER ASSIGN UNASSIGN UNASSIGNALL CLOCKADJUST COMn Injects almanac Injects ionospheric refraction corrections Injects latest computed position, velocity and acceleration Injects raw GPS ephemeris data Injects RTCA format DGPS corrections in ASCII (Type 1) Injects RTCM format differential corrections in ASCII (Type 1) Injects receiver time of 1 PPS Injects UTC informat
2 Command Descriptions Table 2-2 GPSCard Command Summary (continued) MAGVAR MESSAGES POSAVE RESET RINEX RTCM16T Set magnetic variation correction Disable error reporting from command interpreter Implements position averaging for reference station Performs a hardware reset (OEM only) Configure the user defined fields in the file headers EnterValue an ASCII text message to be sent out in the RTCM data Range stream RTCMRULE Set variations of the RTCM bit rule RTKMODE Set up the RTK mode SAVEALMA Save the lat
2 Command Descriptions When the GPSCard is first powered up, or after a FRESET command, all commands will revert to the factory default settings. An example is shown below. The SAVECONFIG command can be used to modify the power-on defaults. Use the RCCA log to reference station command and log settings. Note: All previously stored configurations that were saved to non-volatile memory are erased (including Saved Config, Saved Almanac, and Channel Config).
2 Command Descriptions All Commands: 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. So, the checksum of a command with parameters will change if the parameters are modified. NOTE: The command must be typed in uppercase for the proper checksum to be calculated.
3 Special Data Input Commands 3 2SPECIAL DATA INPUT COMMANDS 3 SPECIAL DATA INPUT COMMANDS These entries are data messages that are generated by one GPSCard and sent to another. For example, consider a special configuration in which a GPSCard #1 is able to send these data messages to a GPSCard #2 via a serial port. For GPSCard #1, this is no different than sending these data messages to a file or a screen.
3 Special Data Input Commands REMEMBER: When connecting two GPSCard COM ports together, the MESSAGES command option should be set to "OFF" to prevent inter-card "chatter". The MiLLennium GPSCard can log current almanac data to a PC connected to its COM1 or COM2 port. Assuming the PC is correctly configured using terminal emulator communications software, then the PC can redirect the GPSCard almanac log to its disk storage device.
3 Special Data Input Commands $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.
3 Special Data Input Commands Appendix D. 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 Special Data Input Commands $TM1A/B Receiver Time of 1PPS The $TM1A and TM1B data messages can be used to time-synchronize multiple receivers which are all referencing the same external oscillator. First, ensure that SETTIMESYNC is enabled. Next, the primary unit must be sending its 1PPS signal to the MARKIN input of the secondary unit. Third, the two units must be communicating via a COM port.
4 Data Logs 4 4 DATA LOGS DATA LOGS 4.1 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.
4 Data Logs by using the UNLOGALL command (see Chapter 2 and Appendix C). All activated logs will be listed in the receiver configuration status log (RCCA). 4.2 NovAtel FORMAT DATA LOGS General The GPSCard is capable of executing more than 40 NovAtel format log commands. Each log is selectable in ASCII and Binary formats. The one exception to this rule is the RGE log, which can be logged as RGED. The “D” indicates a compressed binary format to allow higher speed logging.
4 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.
4 Data Logs 4.4 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. The following table contains excerpts from Table 6 of the NMEA Standard which defines the variables for the NMEA logs.
4 Data Logs 4.5 GPS TIME VS LOCAL RECEIVER TIME All logs report GPS time expressed in GPS weeks and seconds into the week. The time reported is not corrected for local receiver clock error. To derive the closest GPS time, one must subtract the clock offset shown in the CLKA log (field 4) from GPS time reported. GPS time is based on an atomic time scale.
4 Data Logs Table 4-1 Logs By Function Table (continued) SATELLITE TRACKING AND CHANNEL CONTROL Logs Descriptions ALMA/B Current decoded almanac data DOPA/B ETSA/B DOP of SVs currently tracking 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 RASA/B Raw almanac Raw GPS almanac set RGEA/B/D Satellite range measurements SATA/B Satellite specific informat
4 Data Logs Table 4-1 Logs By Function Table (continued) POST PROCESSING DATA Logs Descriptions BSLA/B Most recent matched baseline expressed in ECEF coords.
4 Data Logs Table 4-2 GPSCard Log Summary (continued) NMEA Format Logs GPALM Almanac Data GPGSV GPS Satellites in View GPGGA Global Position System Fix Data GPRMB Generic Navigation Information GPGLL Geographic Position - lat/lon GPRMC GPS Specific Information GPGRS GPS Range Residuals for Each Satellite GPVTG Track Made Good and Ground Speed GPGSA GPS DOP and Active Satellites GPZDA UTC Time and Date GPGST Pseudorange Measurement Noise Statistics GPZTG UTC & Time to Destination Wa
5 Special Pass-Through Logs 5 SPECIAL PASS-THROUGH LOGS 5 SPECIAL PASS-THROUGH LOGS 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.
5 Special Pass-Through Logs Figure 5-1 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 recogni
5 Special Pass-Through Logs 5.2 ASCII LOG STRUCTURE $port ID week Field # Field type 1 $port ID 2 3 4 week seconds pass-through data 5 6 *xx [CR][LF] seconds pass-through data Data Description *xx [CR][LF] Example Log header: Identifies port accepting input data GPS week number GPS seconds into the week at time of log Data accepted into COM1 (up to 80 characters) Checksum Sentence terminator $COM1 747 347131.23 $TM1A,747,347131.000000000, 0.000000058,0.000000024, -9.
5 Special Pass-Through Logs Example 1b: $COM1,747,349005.18,Dk4 3MA<83>o<82>Z<97>I <91>iV><7F><8F>O"*6A As can be seen, the $TM1B binary data at the accepting port was converted to a variation of ASCII hexadecimal before it was passed through to COM2 port for logging (MESSAGES command set to OFF). 5.
6 Message Formats 6 MESSAGE FORMATS 6 MESSAGE FORMATS In a NovAtel RTK positioning system, the observations transmitted by a NovAtel reference station to a NovAtel remote station can be in either a proprietary RTCA Type 7 or a proprietary RTCM Type 59N message format.
6 Message Formats RTCAREF TYPE 7 An RTCAREF (RTCA Reference Station Position Information) message contains reference station position information, and should be sent once every 10 seconds. Each message is 24 bytes (192 bits) long. If RTCA-format messaging is being used, the optional station id field that is entered using the FIX POSITION command can be any 4-character string combining numbers and upper-case letters, and enclosed in quotation marks (e.g. “RW34”).
6 Message Formats This message was designed so that RTCA data can be intermixed with other NovAtel ASCII data over a common communications port. The log is not in pure RTCA format. The header ($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. The RTCAA log can be directly decoded by other NovAtel GPSCard receivers operating as remote stations.
6 Message Formats positioning algorithm would be used. This is for a system in which both the reference and remote stations utilize NovAtel receivers. Note that the error-detection capability of an RTCM-format message is less than that of an RTCA-format message. The communications equipment that you use may have an error-detection capability of its own to supplement that of the RTCM message, although at a penalty of a higher overhead (see the discussion at the beginning of this chapter).
6 Message Formats RTCM General Message Format All GPSCard RTCM standard format logs adhere to the structure recommended by RTCM SC-104. Thus, all RTCM message are composed of 30 bit words. Each word contains 24 data bits and 6 parity bits.
6 Message Formats text can be transmitted as a NovAtel Format ASCII log by utilizing the "LOG port RTCM16T" command. Syntax: RTCM16T message Syntax RTCM16T message Range Value up to 90 characters Description Command ASCII text message Example: rtcm16t This is a test of the RTCM16T Special Message.
6 Message Formats ASCII The format of the NovAtel ASCII version of an RTCM log is as follows: Structure: header rtcm data Field # *xx Field Type 1 2 header rtcm data 3 4 *xx [CR][LF] [CR][LF] Data Description Example NovAtel format ASCII header hexadecimal representation of binaryformat RTCM SC104 data Checksum Sentence terminator $RTCM3 597E7C7F7B76537A66406F49487F79 7B627A7A5978634E6E7C5155444946 *68 [CR][LF] Example: $RTCM3,597E7C7F7B76537A66406F49487F797B627A7A5978634E6E7C515544494 6*68[C
6 Message Formats RTCMA or RTCM1A This log contains the same data available in the RTCM Standard Format Type 1 messages, but has been modified to allow flexibility in using the RTCM data. The RTCM data has been reformatted to be available in ASCII hexadecimal, utilizing a NovAtel header and terminates with a checksum. This message was designed so that RTCM data can be intermixed with other NovAtel ASCII data over a common communications port. The log is not in pure RTCM SC104 format.
6 Message Formats 567C7F5B69796F40547F73595557555546*51[CR][LF] RTCM1B Message ID = 10 RTCM3 Message byte count = variable REFERENCE STATION PARAMETERS RTK This log contains the GPS position of the reference station expressed in rectangular ECEF coordinates based on the center of the WGS84 ellipsoid. This log uses four RTCM data words following the two-word header, for a total frame length of six 30 bit words (180 bits maximum).
6 Message Formats Type 9 messages contain the following information for a group of three satellites in view at the reference station: • Scale factor • User Differential Range Error • Satellite ID • Pseudorange correction • Range-rate correction • Issue of Data (IOD) RTCM9A Example: $RTCM9,66516277547C71435D797760704260596876655F7743585D547562716D7 57E686C5258*6D[CR][LF] RTCM9B Message ID = 42 RTCM16 Message byte count = variable SPECIAL MESSAGE This log contains a special ASCII message that
6 Message Formats RTCM59 TYPE 59N-0 NOVATEL PROPRIETARY MESSAGE RTK RTCM Type 59 messages are reserved for proprietary use by RTCM reference station operators. Each message is variable in length, limited only by the RTCM maximum of 990 data bits (33 words maximum). The first eight bits in the third word (the word immediately following the header) serve as the message identification code, in the event that the reference station operator wishes to have multiple Type 59 messages.
7 Rinex-Standard Commands & Logs 7 RINEX-STANDARD COMMANDS & LOGS 7 RINEX-STANDARD COMMANDS & LOGS 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.
7 Rinex-Standard Commands & Logs 7.1 COMMANDS RINEX This command is used to configure the user-defined fields in the file headers. The settings of all these fields are visible in the RCCA log. All settings can be saved to non-volatile memory on a MiLLennium card by the SAVECONFIG command. A CRESET command will empty all text fields and reduce to zero the antenna offsets.
7 Rinex-Standard Commands & Logs Note that the RCCA log shows any non-default RINEX settings. 7.2 LOGS RINEX Observation and Navigation Logs and Headers This pseudo - log type exists to simplify the commands for the user. For example, at the command COM1> log com2 rinex ontime 30 the XOBS and XNAV logs are both started. When it is time to cease data collection, the command COM1> unlog com2 rinex or COM1> unlogall will stop the XOBS and XNAV logs, and the XNHD and XOHD logs will be generated once.
7 Rinex-Standard Commands & Logs XNHD Navigation Header This log consists of a RINEX-format header for broadcast navigation message files. It can be generated at any point, using a command such as COM1> log com2 xnhd or it will be generated automatically when logging is complete, using a command such as COM1> unlogall Log example: $XNHD, 2 NAVIGATION DATA $XNHD, NovAtel GPSCard NATIVE 96-04-10 16:13 $XNHD,Field trial of new receiver $XNHD,.10245D-07 .14901D-07 $XNHD,.88064D+05 .
7 Rinex-Standard Commands & Logs Log example: $XOHD, 2 OBSERVATION DATA G (GPS) $XOHD,NovAtel GPSCard NATIVE 96-04-10 16:04 $XOHD,Field trial of new receiver $XOHD,A980 $XOHD,980.1.34 $XOHD,S.C. Lewis NovAtel Surveying Service Ltd. $XOHD,LGN94100019 GPSCard-2 FRASER 3.41RC12 $XOHD,Field #1 NovAtel 501 $XOHD, -1634937.3828 -3664677.1214 4942285.1723 $XOHD, 2.7000 0.0500 0.1000 $XOHD, 1 0 7 G 2 G 3 G16 G18 G19 G22 G27 $XOHD, 1 0 3 G28 G29 G31 $XOHD, 3 C1 L1 D1 $XOHD, 5 $XOHD, 1996 4 10 16 4 43.
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 All these parts operate together to provide accurate three dimensional positioning, timing and velocity data to users worldwide. The Space Segment The space segment is composed of the NAVSTAR GPS satellites. The final constellation of the system consists of 24 satellites in six 55° orbital planes, with four satellites in each plane. The orbit period of each satellite is approximately 12 hours at an altitude of 10,898 nautical miles.
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 Precision 4 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 GPS antenna (shown with choke-ring ground plane) Radio RX GPS RX Radio TX GPS RX Remote station 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 metres, whereas night time levels are much lower and may be up to 6 metres. • Tropospheric Refraction Delays – The earth’s tropospheric layer causes GPS signal propagation delays which bias the range measurements.
A GPS Overview 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 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. Pseudorange differential positioning is quite effective in largely removing most of the biases caused by satellite clock error, ionospheric and tropospheric delays (for baselines less than 50 km), ephemeris prediction errors, and SA.
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 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 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. Close-in reflections will be stronger, and typically have a shorter propagation delay allowing for autocorrelation of signals with a propagation delay of less than one C/A code chip (300 metres). Figure B-2 Illustration of GPS Signal Multipath vs.
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 NovAtel’s Internal Receiver Solutions for Multipath Reduction The multipath antenna hardware solutions described in the previous paragraphs are capable of achieving varying degrees of multipath reception reduction. These options, however, require specific conscious efforts on the part of the GPS user. In many situations, especially kinematic, few (if any) of the above solutions may be effective or even possible to incorporate.
C Commands Summary C C 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 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 Commands Summary OUTPUT DATA DTR Data 150 ms 300 ms lead tail 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 example at the beginning of Chapter 2. 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.
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.
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; however, if a satellite being tracked drops below this angle, it will continue to be tracked until the signal is lost. Satellites that are below the cutoff angle will be eliminated from the internal position and clock offset solution computations only.
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 metres.
C Commands Summary FIX POSITION (RTK) 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 metres 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.
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 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.
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 5 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.
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 RINEX Commands Summary Receiver-Independant 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 6, Message Formats, RTCM Commands and Logs, for related topics.
C Commands Summary RTCMRULE This command allows the user flexibility in the usage of the RTCM Standard "bit rule". See Chapter 6, Message Formats, 6.2 RTCM - Format Messages, for further information.
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 Command Argument Commands Summary 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 Commands Summary Station Remote Command rtkmode Argument 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 Station Remote Command rtkmode Commands Summary 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, Appendix D) 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.
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 reissued 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 Commands Summary Figure C-5 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 1 112 MiLLennium Command Descriptions Manual
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 4 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.
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 ALMA Structure: $ALMA prn ecc Mo af0 ra w A incl-angle seconds week rate-ra cor-mean-motion af1 health-4 health-5 health-alm *xx [CR][LF] ALMA FORMAT Field # Field type Data Description Example 1 2 3 4 5 6 7 8 9 $ALMA prn ecc seconds week rate-ra ra w Mo Log header Satellite PRN number for current message, dimensionless Eccentricity, dimensionless Almanac reference time, seconds into the week Almanac reference week (GPS week number) Rate of right ascension, radians Ri
D Logs summary IONA FORMAT Structure: $IONA act a1ot a2ot a3ot bct b1ot b2ot b3ot *xx Field # Field type [CR][LF] Data Description Example 1 2 3 4 $IONA act a1ot a2ot Log header Alpha constant term, seconds Alpha 1st order term, sec/semicircle Alpha 2nd order term, sec/(semic.)2 $IONA 1.0244548320770265E-008 1.4901161193847656E-008 -5.960464477539061E-008 5 a3ot -1.192092895507812E-007 6 7 8 bct b1ot b2ot Alpha 3rd order term, sec/(semic.
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 9 124 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 16 126 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 Data Description Example A running count of DCSA records that pass error checking 0 A running count of invalid binary DCSB records 0 A running count of DCSB records that pass error checking 0 28 Reserved for future use 0 29 Reserved for future use 0 26 7dcsbchk 27 dcsbgood 30 Reserved for future use 0 31 *xx Checksum *33 32 [CR][LF] Sentence terminator [CR][LF] Example: $CDSA,787,500227,0,0,0,0,0,0,9,0,0,0,0,0,0,9,0,0,0,0,0,0,0,
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 9 132 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 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) Bytes 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 Symbol 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. NOTES: 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 T track mag K *xx $GPVTG track true T track mag 5 6 7 8 9 10 11 M speed Kn N speed Km K *xx [CR][LF] speed Km [CR][LF] Structure 1 2 3 4 M 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 1 2 3 4 5 6 7 8 9 Structure $GPZDA utc day month year null null *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 ➀ 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. REMEMBER: SETNAV 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 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 MiLLennium Command Descriptions Manual
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.
D Logs summary PAVB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 160 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
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 Appendix A, Section A.3.
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 behaviour 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 Message byte count = 108 Field Type 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 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 for a definition of the coordinates.
D Logs summary PXYB Format: Field # 1 (header) 2 3 4 5 6 7 8 9 10 11 12 Message ID = 26 Message byte count = 88 Data 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 Differential lag, age of differential corrections Bytes ➀ ➀ 3 1 4 4 4 8 8 8 8 8 8 8 4 4 8 Format char char integer integer integer double double double double double double double integer integer double Units weeks seconds metres metres metres
D Logs summary Figure D-2 The WGS84 ECEF Coordinate System 168 MiLLennium Command Descriptions Manual
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 11 12 13... Message ID = 66 Message byte count = 40 + (n * 32) 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 for the RCCA default list. RCCA Example: $RCCA,COM1,9600,N,8,1,N,OFF,ON*2B $RCCA,COM2,9600,N,8,1,N,OFF,ON*28 $RCCA,COM1_DTR,HIGH*70 $RCCA,COM2_DTR,HIGH*73 $RCCA,COM1_RTS,HIGH*67 $RCCA,COM2_RTS,HIGH*64 $RCCA,UNDULATION,TABLE*56 $RCCA,DATUM,WGS84*15 $RCCA,USERDATUM,6378137.000,298.257223563,0.000,0.000,0.
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 Field # [CR][LF] Field type Data Description Example 1 2 3 4 5 6 7 $RGEA week seconds # obs rec status prn psr 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, following) Satellite PRN
D Logs summary RGEB Format: Message ID = 32 Field # 1 (header) Message byte count = 32 + (obs x 44) Data Bytes Format Units Offset 2 3 4 5 6 7 8 9 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 3 1 4 4 4 8 4 4 4 8 4 8 char char integer integer integer double integer integer integer double float double 10 StdDev - accumulated Doppl
D Logs summary RGED Format: Message ID = 65 Field # Data 1 (header) Sync Checksum Message ID Message byte count Number of obs Week number Seconds of week Receiver status First PRN range record 2 3 4 5 6 Message byte count =24 + (20 x number of obs) Bytes 3 1 4 4 2 2 4 4 20 Format Scale char char integer integer integer integer See Table D-6, following the Detailed Bit Descriptions of the Self-Test 1 1 1/100 1 Offset 0 3 4 8 12 14 16 20 24 Next PRN offset = 24 + (20 x number of obs) MiLLenniu
D Logs summary Table D-5 Receiver Self-Test Status Codes N7 N 6 27 26 25 N 5 24 23 22 21 N 4 20 N 3 19 18 17 16 15 14 13 12 11 N 2 10 9 N 1 8 7 6 5 N 0 4 3 2 1 0 <- <- Nibble Number B it Descriptio n lsb = 0 ANTENNA 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 COM 1 1 =good, 0 =bad 00000040 7 COM 2 1
D Logs summary 1 This bit will be set to 1 when the digital signal processors (DSP) have passed the self-test requirements. 0 If this bit is set to 0, one or both of the Service. Bit 5 L1 AGC 1 When set to 1, the L1AGC circuits are operating within normal range of control. 0 This bit will be set clear if the L1AGC is operating out of normal range.
D Logs summary Bit 16 Almanac Saved 0 Almanac not saved in non-volatile memory. 1 Almanac saved in non-volatile memory (12 channel OEM cards only). Bit 17 L2AGC 1 When set to 1, the L2ARG circuits are operating within normal range of control. 0 This bit will be set clear if the L2AGC is operating out of normal range.
D Logs summary Table D-6 Range Record Format (RGED only) Data PRN ① C/No ② Lock time ③ ADR ④ Doppler frequency Pseudorange StdDev - ADR StdDev - pseudorange Channel Tracking status ➅ Bit(s) from first to last Length (bits) 0..5 6..10 11.31 32..63 68..95 64..67 msn; 96..127 lsw 128..131 132..135 136..159 6 5 21 32 28 36 4 4 24 Format integer integer integer integer 2's comp. integer 2's comp. integer 2's comp.
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 N 1 8 7 6 5 N 0 4 3 2 1 0 <- <- Nibble Number Bit Description Range Values lsb =0 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 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: Field # 1 (header) 2 3 4 5 6 7 8 9 8 & 9 are repeated for each card Message ID = 56 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 float intege
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. 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: Message ID = 34 Field # Message byte count = 72 Data 1 (header) 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 2 3 4 5 6 7 8 9 10 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 se
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-5 RT-20 Performance Tracking Time (sec) Mode ① Data Delay (sec) Distance (km) Accuracy (CEP) 1 - 180 180 - 3000 > 3000 Static Static Static 0 0 0 1 1 1 100 to 25 cm 25 to 5 cm 5 cm or less 1 - 600 600 - 3000 > 3000 Kinematic Kinematic Kinematic Either Either Either Either Either Either Either Either 0 0 0 0-2 2-7 7 - 30 30 - 60 > 60 0 0 0 1 1 1 1 1 1 1 1 0 - 10 10 - 20 20 - 50 100 to 25 cm 25 to 5 cm 5 cm or less +1 cm/sec +2 cm/sec +5 cm/sec +7 cm/sec (s
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.
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 2. If the loss of differential corrections lasts longer than 30 seconds, the RT-20 filter is reset and all ambiguity and monitor model information is lost. The timeout threshold for RT-20 differential corrections is 30 seconds, but for Type 1 pseudorange corrections, the timeout is 60 seconds.
F Standards and References F F STANDARDS AND REFERENCES 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) 16 GEO49 84 -22 209 Geodetic Datum 1949 (New Zealand) International 1924 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
G Geodetic Datums Notes: * Default user datum is WGS84. * Also see the DATUM and USERDATUM commands in Chapter 2 and Appendix C. * The GPSCard DATUM command sets the Datum value based on the name entered as listed in the "NAME" column in Table G-2 (e.g., NAD83). * The following GPSCard logs report Datum used according to the "GPSCard Datum ID" column: B, PRTKA/B, RTKA/B, and MKPA/B.
H Some Common Unit Conversions H SOME COMMON UNIT CONVERSIONS H SOME COMMON UNIT CONVERSIONS Listed below are several 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. Distance 1 metre (m) = 100 centimetres (cm) = 1000 millimetres (mm) Volume 1 kilometre (km) = 1000 metres (m) 1 litre (l) = 1000 cubic centimetres (cc) 1 international foot = 0.3048 metre 1 gallon (British) = 4.
I Information Messages INFORMATION MESSAGES I I INFORMATION MESSAGES 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 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 MONITOR STATION Required: REMOTE STATION Required: FIX POSITION lat lon hgt id (health) LOG port DATATYPE ontime 5 Recom m ended Options: ACCEPT port DATATYPE Recom m ended Options: (binary): RTCMB RTCAB RTCM RTCA ACCEPT DATATYPES (binary): RTCM RTCA (ascii): RTCMA RTCAA Related Com m ands /Logs: RTCMRULE DATUM ACCEPT COM M ANDS (ascii): RTCMA RTCAA LOG DATATYPES LOG DATATYPES Related Com m ands /Log
J Listing Of Tables Table 2-1 Commands By Function Table COMMUNICATIONS, CONTROL AND STATUS Commands Descriptions ANTENNAPOWER Power to the low-noise amplifier of an active antenna COMn COMn_DTR COMn port configuration control DTR handshaking control COMn_RTS RTS handshaking control DIFF_PROTOCOL FREQUENCY_OUT Differential Protocol Control Variable frequency output (programmable) LOG MESSAGES Logging control Disable error reporting from command interpreter RINEX Configure the user defined field
J Listing Of Tables Table 2-1 Commands By Function Table (continued) SATELLITE TRACKING AND CHANNEL CONTROL Commands Descriptions $ALMA Download almanac data file ASSIGN CONFIG Satellite channel assignment Switches the channel configuration of the GPSCard DYNAMICS Sets correlator tracking bandwidth FIX VELOCITY RESETHEALTH Aids high velocity reacquisition Reset PRN health SETHEALTH Overrides broadcast satellite health WAYPOINT NAVIGATION Commands Descriptions MAGVAR Magnetic variation correct
J Listing Of Tables Table 2-2 GPSCard Command Summary Command $ALMA $IONA $PVAA $REPA $RTCA $RTCM $TM1A $UTCA ACCEPT ANTENNAPOWER ASSIGN UNASSIGN UNASSIGNALL CLOCKADJUST COMn COMn_DTR COMn_RTS CONFIG CRESET CSMOOTH DATUM USERDATUM DGPSTIMEOUT DIFF_PROTOCOL DYNAMICS ECUTOFF EXTERNALCLOCK EXTERNALCLOCK FREQUENCY FIX HEIGHT FIX POSITION FIX VELOCITY UNFIX FREQUENCY_OUT FRESET HELP or ? LOCKOUT UNLOCKOUT UNLOCKOUTALL LOG UNLOG UNLOGALL Description Injects almanac Injects ionospheric refraction corrections Inj
J Listing Of Tables Table 2-2 GPSCard Command Summary (continued) MAGVAR MESSAGES POSAVE RESET RINEX RTCM16T SETNAV Set magnetic variation correction Disable error reporting from command interpreter Implements position averaging for reference station Performs a hardware reset (OEM only) Configure the user defined fields in the file headers Enter an ASCII text message to be sent out in the RTCM data stream Set variations of the RTCM bit rule Set up the RTK mode Save the latest almanac in non-volatile memo
J Listing Of Tables Table 4-1 Logs By Function Table COMMUNICATIONS, CONTROL AND STATUS Logs Descriptions CDSA/B COM port communications status COM1A/B COM2A/B Log data from COM1 Log data from COM2 COMnA/B Pass-through data logs RCSA/B RTCM16T Receiver self-test status NovAtel ASCII format special message RTCM16 RTCM format special message GENERAL RECEIVER CONTROL AND STATUS Logs Descriptions PVAA/B Receiver’s latest computed position, velocity and acceleration in ECEF coordinates RCCA Rece
J Listing Of Tables Table 4-1 Logs By Function Table (continued) Logs WAYPOINT NAVIGATION Descriptions GPRMB NMEA, waypoint status GPRMC NMEA, navigation information GPVTG GPZTG NMEA, track made good and speed NMEA, time to destination MKPA/B NAVA/B Position at time of mark input Navigation waypoint status POSA/B 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 inform
J Listing Of Tables Table 4-2 GPSCard Log Summary Syntax: log port,datatype,[trigger],[period],[offset],{hold} NovAtel Format Logs Datatype ALMA/B BSLA/B CDSA/B Description Datatype Description Decoded Almanac Baseline Measurement Communication and Differential Decode Status Receiver Clock Offset Data Receiver Clock Model Log data from COM1 Log data from COM2 RALA/B RASA/B RCCA Raw Almanac Raw GPS Almanac Set Receiver Configuration REPA/B RGEA/B/D RPSA/B RTCAA/B RTKA/B RTKOA/B RTCMA/B MKPA/B MKTA/B
J Listing Of Tables Table 6-1 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 Table D-6 Range Record Format (RGED only) Data PRN ① C/No ② Lock time ③ ADR ④ Doppler frequency Pseudorange StdDev - ADR StdDev - pseudorange ChannelTracking status ➅ Bit(s) from first to last Length (bits) 0..5 6..10 11.31 32..63 68..95 64..67 msn; 96..127 lsw 128..131 132..135 136..159 6 5 21 32 28 36 4 4 24 Format integer integer integer integer 2's comp. integer 2's comp. integer 2's comp.
J Listing Of Tables 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 N 1 8 7 6 5 N 0 4 3 2 1 0 <- <- Nibble Number Bit Description Range Values lsb =0 Hex.
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 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. It is commonly used as a way to label a particular satellite. Pseudolite — an Earth-based transmitter designed to mimic a satellite. May be used to transmit differential corrections.
K GPS Glossary of Terms Spherical Error Probable (SEP) — the radius of a sphere, centred at the user’s true location, that contains 50 percent of the individual three-dimensional position measurements made using a particular navigation system. Spheroid — sometimes known as ellipsoid; a perfect mathematical figure which very closely approximates the geoid. Used as a surface of reference for geodetic surveys. The geoid, affected by local gravity disturbances, is irregular.
K GPS Glossary of Terms VDOP — Vertical Dilution of Precision. This is related to GDOP. It describes the effects of geometry on vertical positioning accuracy. It is defined to be the square root of the diagonal of a normalized (assume measurement noise = 1) covariance matrix which corresponds to vertical position error.
L GPS Glossary of Acronyms L GPS GLOSSARY OF ACRONYMS L GPS GLOSSARY OF ACRONYMS 1PPS 2D 3D One Pulse Per Second Two Dimensional Three Dimensional A/D ADR AGC ASCII Analog-to-Digital Accumulated Doppler Range Automatic Gain Control American Standard Code for Information Interchange BIH BIST bps Bureau l’International de l’Heure Built-In-Self-Test Bits per Second C/A Code CEP CPU CR CRC CTP CTS CTS Coarse/Acquisition Code Circular Error Probable Central Processing Unit Carriage Return Cyclic Redund
L GPS Glossary of Acronyms MEDLL MKI MKO msb msec MSL Multipath Estimation Delay Lock Loop Mark In Mark Out Most significant bit millisecond Mean sea level N. mi.
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