GPSSUBFRAME(1)		      GPSD Documentation		GPSSUBFRAME(1)

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

GPSD Version 3.26.1		  2025-05-06			GPSSUBFRAME(1)