NAME

       gpssubframe - tool to dump subframe sentences from gpsd

SYNOPSIS

       gpssubframe [OPTIONS] [server[:port[:device]]]

       gpssubframe -h

       gpssubframe -V

DESCRIPTION

       gpssubframe is a tool to connect to gpsd and dump decoded subframe data to stdout. This is
       only useful if your GNSS receiver can output GPS subframe messages, and is configured to
       do so. A working knowledge of IS-GPS-200 is also required. Keep your copy close at hand.

       gpssubframe does not require root privileges, but will run fine as root. It can be run
       concurrently with other tools connecting to the local gpsd without causing problems.

       The program will accumulate subframe messages and output them by GPS satellite number on
       exit. By default the program never exits unless the user selects the number of seconds to
       run or number of messages to capture.

       By default gpssubframe connects to a gpsd running on the local host. Optionally a host,
       TCP/IP port number and remote device can be given.

OPTIONS

       -?, -h, --help
           -Print a usage message and exit.

       -c COUNT, --count COUNT
           Exit after COUNT subframe messages.

       -D DEBUG, --debug DEBUG
           Set level of debug. Must be integer. Default 0.

       --desc
           Print long descriptions.

       --device DEVICE
           Connect to device DEVICE on gpsd host.

       -D LVL, --debug LVL
           Set debug level to LVL.

       --file FILE
           Read gpsd JSON from FILE instead of from gpsd..

       --host HOST
           Connect to gpsd on host HOST.

       --load LOADFILE
           Load saved JSON Subframe, TPV, and RAW data trom LOADFILE.

       -n COUNT, --count COUNT
           Count of messages to parse. 0 to disable.

       --port PORT
           Connect to gpsd on port PORT.

       --progress
           Print progress reports as messages are received.

       --satpos
           Compute GPS satellite positions before exit. If --time is given, the positions will be
           calculated at the time. Otherwise if a RAW message was received, the measurement time
           in that message will be used. The last resort is to use the time from the last TPV
           message is used.

       --save SAVEFILE
           Save decoded Subframe data in SAVEFILE as JSON. If present, the last TPV and RAW JSON
           records will also be saved.

       --test
           Run --satpos selftest code.

       --time SEC
           Compute satellite position at time SEC in POSIX seconds.

       -V, --version
           Print the program version, then exit.

       -x SEC, --seconds SEC
           Seconds of messages to parse. 0 to disable.

ARGUMENTS

       By default, clients collect data from the local gpsd daemon running on localhost, using
       the default GPSD port 2947. The optional argument to any client may override this
       behavior: [server[:port[:device]]]

       For further explanation, and examples, see the ARGUMENTS section in the gps(1) man page

EXAMPLES

       First configure a u-blox 9-series to output subframe messages. Then have gpssubframe
       gather one complete set of subframes, then print the data organized by GPS satellite
       number. Be sure to replace -P 22 with the correct protocol version for your receiver. Then
       calculate and print the known satellite positions as well as the azimuth, elevation, and
       range from the current position:

           ubxtool -P 22 -e SFRBX
           gpssubframe -x 750 --satpos

       If staring at a blank screen for 12.5 minutes is too stressful, then enable progress
       messages:

           gpssubframe -x 750 --satpos --progress

RETURN VALUES

       0
           on success.

       1
           on failure

SEE ALSO

       gpsd(8), gps(1), gpsprof(1), gpsfake(1).

       IS-GPS-200 "NAVSTAR GPS Space Segment/Navigation User Segment Interfaces"

RESOURCES

       Project web site: https://gpsd.io/

COPYING

       This file is Copyright 2020 by the GPSD project
       SPDX-License-Identifier: BSD-2-clause

AUTHOR

       Gary E. Miller