NAME

       zerk - All purpose GREIS fitting

SYNOPSIS

       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[1].

       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:

       -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.

       -h
           Makes zerk print a usage message and exit.

       -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.

       -v VERBOSITY
           Set verbosity level to VERBOSITY. Verbosity can be from 0 (very quiet), 2 (decode
           messages), to 4 (very noisy). Default 1.

       -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.

       -?
           Makes zerk print a usage message and exit.

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[1].

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

AUTHOR

       Gary E. Miller<gem@rellim.com>

NOTES

        1. GREIS (GNSS Receiver External Interface Specification) Guide
           http://www.javad.com/downloads/javadgnss/manuals/GREIS/GREIS_Reference_Guide.pdf