6 December 2020
zerk 1 The GPSD Project GPSD Documentation
zerk All purpose GREIS fitting
`zerk` -? -c command -d disable -e enable -f file/device -h -O oaf -p preset -R rawfile -r -S setspeed -s speed -V -v verbosity -W -w wait [server[:port[:device]]]

## DESCRIPTION

zerk is an all purpose GREIS fitting. If you do not have a Javad GPS that speaks the GREIS protocol then you can stop reading now.

This tool operates with your Javad GPS at a very low level. To understand zerk you must first be familiar with your Javad GPS and the documentation for the GREIS protocol. GREIS (GNSS Receiver External Interface Specification) Guide.

zerk can decode common GREIS messages, poll the GPS status, enable and disable GPS features, and send user generated commands to the GPS. It can read GREIS messages from a file. It can read and write directly through a serial device, or through a running gpsd instance.

## OPTIONS

The program accepts the following options:

`-?`
`-h`

  Makes zerk print a usage message and exit.

`-c COMMAND`

  Send a text string to the GPS. Accepts one parameter, COMMAND, the command string to send to the GPS. The string is sent verbatim, except a newline is appended.

`-d OPTION`

  Disable an option in the GPS. Accepts one parameter, OPTION, the option to disable. zerk will exit after the GPS acknowledges the command, unless the -W is given.

  4HZ

    Disable basic GREIS messages at 4Hz. The messages are: [RT], [UO], [GT], [PV], [SG], [DP], [SI], [EL], [AZ], [EC], [SS], and [ET]

  COMPASS

    Disable use of the COMPASS (BeiDou) constellation.

  CONS

    Disable use of all constellations.

  DEFMSG

    Disable the default message set (/dev/msg) at 1Hz.

  GALILEO

    Disable use of the GALILEO constellation.

  GLONASS

    Disable use of the GLONASS constellation.

  GPS

    Disable use of the GPS constellation.

  IPR

    Disable all Integer Pseudo Range messages. These are [rx], [rc], [r1], [r2], [r3], [r5], [rl].

  IRNSS

    Disable use of the IRNSS constellation.

  NMEA

    Disable basic NMEA 4.1e messages at 4Hz. The messages are GBS, GGA, GSA, GST, GSV, RMC, VTG, and ZDA.

  QZSS

    Disable use of the QZSS constellation.

  SBAS

    Disable use of the SBAS constellation.

  SNR

    Disable all SNR messages, except [EC]. The messages disabled are: [E1], [E2], [E3], [E5], [El].

`-e OPTION`

  Enable an option in the GPS. Accepts one parameter, OPTION, the option to enable. zerk will exit after the GPS acknowledges the command, unless the -W is given. -e accepts the same OPTIONs as -d, except the action is to enable the option.

`-f FILE`

  Connect to a file or device. Accepts one parameter, FILE, the file or device to open. Files are opened read-only. Character devices are opened read/write, unless the -r parameter is given. Requires the pyserial module.

`-O OAF`

  Load an Option Authorization File (OAF) into the GPS. Accepts one parameter, OAF, command file to read. The OAF is just a special case of a '.jpo' (GREIS command file). -O will send any valid .jpo file to the GPS.

`-p PRESET`

  Send a preset command the GPS. Accepts one parameter, PRESET, the name of the command to send. zerk will exit after the GPS acknowledges the command, unless the -W is given.

  COLDBOOT

    Coldboot the GPS.

  CONS

    Poll the enabled constellations.

  DM

    Disable all periodic GREIS messages.

  ID

    Poll the receiver ID.

  IPR

    Poll all Integer Pseudo Range messages. These are [rx], [rc], [r1], [r2], [r3], [r5], [rl].

  OAF

    Poll all OAF options.

  RESET

    Reset (reboot) the GPS.

  SERIAL

    Poll receiver serial number.

  SNR

    Poll all Signal to Noise Ratio (SNR) messages. [EC], [E1], [E2], [E3], [E5], [El].

  VENDOR

    Poll GPS vendor.

  VER

    Poll GPS version.

`-r`

  Read only. Do not send anything to the GPS.

`-R RAW`

  Save all raw data from the GPS into the file RAW.

`-S SPEED`

  Configure the GPS serial speed to SPEED bps.

`-s SPEED`

  Set local serial port speed to SPEED bps. Default 115,200 bps.

`-V`

  Print zerk version and exit.

`-v VERBOSITY`

  Set verbosity level to VERBOSITY. Verbosity can be from 0 (very quiet), to 4 (very noisy). Default 2.

`-W`

  Force waiting the entire wait time. No early exit for completion of -d, -e or -p command.

`-w WAIT`

  Wait for WAIT seconds before exiting. Will exit early on command completion of -d, -e or -p command, unless -W is given. Default 2.0 second.

`[server[:port[:device]]]`

  By default, zerk collects data from all compatible devices on localhost, using the default GPSD port 2947. An optional argument may specify a server to get data from. A colon-separated suffix is taken as a port number. If there is a second colon-separated suffix, that is taken as a specific device name to be watched. Further details on the gps 1 man page.

## ENVIRONMENT

Options can be placed in the ZERKOPTS environment variable. ZERKOPTS is processed before the CLI options.

## EXAMPLES

Print current Javad serial portC of GPS connected to local running gpsd::

     zerk -c "print,/cur/term"

Decode raw log file:

    zerk -r -f greis-binary.log -v 2

Change GPS port speed of device on /dev/ttyAMA0 to 230,400 bps::

    zerk -S 230400 -f /dev/ttyAMA0

Watch entire GPS reset cycle:

    zerk -p RESET -v 2 -w 20 -W

Poll SVs Status:

    zerk -W -w 2 -v 2 -c "out,,jps/{CS,ES,GS,Is,WS,QS}"

Dump gpsd data from remote server:

    zerk -v 2 -w 5 server

## SEE ALSO

zerk is written to conform to the official Javad documentation for the GREIS protocol. GREIS (GNSS Receiver External Interface Specification) Guide.

gpsd 8 , gps 1 , cgps 1 , xgps 1 , gpsfake 1 , gpsctl 1 , gpscat 1 , gnuplot 1 .

## AUTHOR

Gary E. Millergem@rellim.com