Novatel Rover/Boat GPS units

Rover/Boat GPS

• This script is used to get the position/boat velocity for a Rio Grande or Streampro ADCP.

gps-rover-riogrande novatel script

• This script should be loaded into a Novatel Smart-V1 rover GPS. When the GPS is powered up, it finds its position from the satellite range data, augmented by the SBAS system, and using corrections received from a base GPS on port COM2.

• Page numbers refer to the Novatel OEMV Firmware Reference Manual.

• The purpose of the rover GPS is to provide detailed and accurate boat position, velocity, and time information to the computer running Winriver ADCP software. Either COM1 (connector J2)or USB1 on the Novatel GPS can be used to provide this information, with GGA (position) and VTG (velocity) strings outputting at 10 Hz, and RMC (time, position, ...) and ZDA (time) strings outputting once per minute.

• Specific ADCP devices or software may require different data rates or specific strings.

• The rover GPS is configured to receive differential corrections on port COM2 (connector J3) from a Freewave or Bluetooth radio, which is paired with another radio connected to the base GPS unit.

• the script:

   unlogall
   
   magvar auto
   sbascontrol enable auto 0 zerototwo
   
   com com1 38400
   com com2 115200
   
   interfacemode com2 rtca none off
   interfacemode usb2 novatel novatel on
   
   log com1 gpggartk ontime 0.1
   log com1 gpvtg ontime 0.1
   log com1 gprmc ontime 60 30
   log com1 gpzda ontime 60
   
   log usb1 gpggartk ontime 0.1
   log usb1 gpvtg ontime 0.1
   log usb1 gprmc ontime 60 30
   log usb1 gpzda ontime 60
   
   log usb3 gpggartk ontime 2
   log usb3 gpvtg ontime 2 1
   log usb3 gprmc ontime 60 30
   log usb3 gpzda ontime 60
   log usb3 bestpos ontime 10
   
   saveconfig
   
   log loglist
   log comconfig

• line-by-line annotations:

unlogall

   The UNLOGALL command (p 216) releases any log commands that may already be set, e.g., perhaps automatically by the Novatel CDU utility. For the Novatel GPS receivers, logging means producing output on one or more ports.

magvar auto

   The MAGVAR command (p 148) configures the rover GPS to report bearing in degrees magnetic. The AUTO parameter tells the GPS to use its internal lookup tables to derive the magnetic variation.

sbascontrol enable auto 0 zerototwo

   sbascontrol (p 187) sets the Satellite Based Augmentation System corrections.

       keyword = ENABLE (or DISABLE)

       Enable/disable SBAS corrections.
       system = AUTO (or ANY, WAAS, EGNOS, MSAS)

       Choose which SBAS system to use. WAAS is for North America, EGNOS is for Europe, and MSAS is for Japan. (So we could probably use WAAS here instead of AUTO.)
       PRN = 0 (or 120-138)

       The PRN, or pseudo-random number, is the identifier for specific SBAS satellites. Value 0 uses any available PRN.
       testmode = ZEROTOTWO (or NONE, IGNOREZERO)

       ZEROTOTWO means to interpret Type 0 messages as Type 2. (I don't know what that means...)

com com1 38400

   COM (p 87) port configuration. Port COM1 uses connector J2 and is used for output from the GPS to the computer at 38400 baud.

com com2 115200

   GPS Com Port COM2 is used for the GPS-to-GPS corrections using connector J3 on the wiring harness, at 115200 baud. This baud rate must match that on the Freewave or Bluetooth radio connected to the rover GPS.

interfacemode com2 rtca none off

   interfacemode (p 135) sets the mode of operation of the specified com port, and must appear after the COM command if used (because COM will reset the interface mode).

   Here we configure COM2 (which uses connector J3) on the rover GPS to receive RTCA corrections from the base GPS via FreeWave or Bluetooth radios.

       port = COM2
       rxtype = rtca
       txtype = none
       responses = OFF

interfacemode usb2 novatel novatel on

   Here we configure the USB2 interface to use novatel mode, which means it accept commands and outputs logs.

       port = USB2
       rxtype = novatel
       txtype = novatel
       responses = ON

log com1 gpggartk ontime 0.1

   The LOG (p 143) command configures the GPS to output information on the specified port and at a given rate and offset. This group of log commands defines what information is sent from the rover GPS via port COM1 (connector J2) to the laptop serial port.

   GPGGARTK messages (p 312) provide high precision time and position data, outputting 10 messages per second. Example message:

       $GPGGA,135324.00,5106.9791988,N,11402.3002127,W,2,09,1.0,1047.606,M,,,04,AAAA*1C

   The GPGGA messages are of paticular interest in that they provide the GPS quality field, a 1-digit number following the longitude direction field, the "W" about in the middle of the message. The quality number should be visible even with messages streaming by at 10 Hz, and allows the operator to assess the state of the corrections being received by the rover GPS.

   During startup, the GPS quality field will be seen to progress from 0 or 1 to 5 (with base corrections) or to 9 (WAAS augmentation).

       0 = fix not available or invalid
       1 = GPS fix
       2 = C/A differential GPS
       4 = RTK fixed ambiguity solution
       5 = RTK floating ambiguity solution
       6 = Dead reckoning mode
       7 = Manual input mode (fixed position)
       8 = Simulator mode
       9 = WAAS

   If the rover Novatel GPS is running with no connection to a base GPS, the best quality number will be 9, indicating WAAS augmentation.

   With a working base GPS sending corrections, the rover GPS should report quality 5, RTK floating ambiguity solution.

log com1 gpvtg ontime 0.1

   The GPVTG (p 335) message is output at 10 Hz, providing track made good and speed relative to the ground data. Example message:

       $GPVTG,172.516,T,155.295,M,0.049,N,0.090,K,D*2B

log com1 gprmc ontime 60 30

   The GPRMC (p 329) message is output once per minute at 30 seconds past the minute, and provides time, date, position, track made good, and speed data. Example message:

       $GPRMC,144326.00,A,5107.0017737,N,11402.3291611,W,0.080,323.3,210307,0.0,E,A*20

log com1 gpzda ontime 60

   The C<GPZDA> (p 337) message is output once per minute, providing UTC
   time and date data.

log usb1 gpggartk ontime 0.1 log usb1 gpvtg ontime 0.1 log usb1 gprmc ontime 60 30 log usb1 gpzda ontime 60

   The same log messages are output on the GPS port B<USB1> as 
   from port B<COM1>, and at the same rate, so either B<COM1> (connector B<J2>)
   or B<USB1> can be used to connect to the laptop.

log usb3 gpggartk ontime 2 log usb3 gpvtg ontime 2 1 log usb3 gprmc ontime 60 30 log usb3 gpzda ontime 60 log usb3 bestpos ontime 10

   The same log messages that are output from the GPS to the laptop are output at a slower rate to port USB3, to provide a way to monitor those messages.

   The BESTPOS log message shows the rover GPS position.

saveconfig

   SAVECONFIG (p 187) writes the configuration into non-volatile memory, so that the configuration remains after power is lost and restored.

log loglist

   LOG LOGLIST (p 355) displays the configured log messages, ports, rates, and offsets for information only.

log comconfig

   LOG COMCONFIG (p 291) displays the ports configuration for information only.

general notes

• To load a script, connect to a suitable port on the GPS using a terminal emulator program, e.g., HyperTerminal, Putty, Minicom (linux), etc.. A suitable port is one that is set to receive in novatel mode, so that commands will be accepted; COM1/J2, USB1, or USB2 are available with this configuration. To test for this, type a command that will produce output, e.g., log loglist, log bestpos, or even just log; if a response is seen then commands should be accepted on that port.

• To use the USB ports from the Novatel GPS on a computer, the Novatel driver must be installed, and then the mapping of the three Novatel USB interfaces to a COM number on the computer has to be determined. CSI DevConfig can be used for this (click on the elipses, ... next to the 'PC Serial Port' box), and will be on the project computers (Toughbook laptops), or the Windows System Device Manager, Ports tab can be used. There should be three Novatel USB Virtual Serial Ports, most likely in consecutive order, but possibly mapped to different numbers than for a previous session.

• Note that the Novatel serial com ports are wired as DCE (data communications equipment), so can connect to a DTE (data terminal equipment) serial port on a computer (laptop) with a straight-through cable.

• Note that typed characters will not be echoed by the novatel GPS, so it may appear that the interface is not working unless a valid command (i.e., one that will generate a response) is entered. (The log command should produce an error message, but that's good enough for this pupose.)