= gpsrinex(1)
:author: Gary E. Miller
:date: 22 February 2025
:email: gem@rellim.com
:keywords: gps, gpsd, gpsrinex, RINEX, ubxtool
:manmanual: GPSD Documentation
:mansource: GPSD, Version {gpsdver}
:robots: index,follow
:sectlinks:
:toc: macro
:type: manpage

include::../www/inc-menu.adoc[]

== NAME

gpsrinex - Read data from gpsd convert to RINEX3 and save to a file.

== SYNOPSIS

*gpsrinex* [OPTIONS] [server[:port[:device]]]

*gpsrinex* -h

*gpsrinex* -V

== DESCRIPTION

*gpsrinex* is a tool to connect to *gpsd* and output the received raw
measurements as a RINEX 3 observation file. This is useful for sending
raw measurements (pseudorange and carrierphase) from *gpsd* to a Precise
Point Positioning (PPP) program or service.

*gpsrinex* does not require root privileges, but may be run as root.
Some of the examples in this file may not work when run under *sudo*.
It can be run concurrently with other tools connecting to a local or
remote *gpsd* without causing problems.

*gpsrinex* needs the GNSS receiver to be sending raw measurements to *gpsd*.
Only a few GNSS have this capability. In addition, the *gpsd* driver for
that GNSS must support raw mode. Currently only the u-blox driver has
this support. Only a few u-blox 8 and 9 receivers implement the required
UBX-RXM-RAWX message. The NEO-M8T is known to work, but requires
configuration with *ubxtool*.

Before using *ubxtool* be sure to set the UBXOPTS environment variable
with the correct protocol version for your u-blox receiver. If your
protocol version is 32.00, you would do this:

----
export UBXOPTS="-P 32.00"
----

RINEX has its own definitions and abbreviations. Be sure to consult
their documentation. An observation file (.obs) contains data sets,
called epochs, that contain the pseudorange and carrierphase for each
satellite seen.

*gpsrinex* by default will acquire 20 epochs spaced apart by 30 seconds.
That will take 10 minutes to complete. Most users consider the 30 second
interval to be optimal. Many PPP programs require at least 1 or 2 hours
data, but no more than 24 or 48 hours of data. Most users consider 4 to
6 hours of data as a minimum for good accuracy. Additional hours will
not yield much improvement.

The output will consist of one RINEX 3 observation file that is ready to
be read by your PPP program. The default filename will be in the form:
_gpsrinexYYYYDDDDHHMM.obs_. You can override this filename with the
*-f* option.

Optionally a server, TCP/IP port number and remote device can be given.
If omitted, *gpsrinex* connects to localhost on the default port (2947)
and watches all devices opened by *gpsd*.

== OPTIONS

*-?*, *-h*, *--help*::
  Print a usage message and exit.
*-D LVL*, *-debug LVL*::
  Set debug level to LVL.
*-f OUTFILE*, *--fileout OUTFILE*::
  save RINEX into FILE.
*-F INFILE*, *--filein INFILE*::
  Read GPS JSON from file, not from a live _gpsd_.
*-i SECS*, *--interval SECS*::
  wait [interval] seconds between epochs. The interval can be specified
  to the millisecond. OPUS accepts intervals of 1, 2, 3, 5, 10, 15 or,30
  seconds. OPUS then reduces the data to 30 second intervals. Default is
  30.000.
*-n COUNT*, *--count COUNT*::
  Causes COUNT epochs to be output. OPUS requires a minimum af 15
  minutes, and a maximum of 48 hours, of data.
*-V*, *--version*::
  makes *gpsrinex* print its version and exit.

The following options set strings that are placed in the generated RINEX
3 obs file. They do not change how *gpsrinex* computes anything.

*--agency AGENCY*::
  The name of the agency creating the current file.
*--ant_num NUMBER*::
  The antenna serial number.
*--ant_type TYPE*::
  The antenna type.
*--marker_name NAME*::
  The marker name.
*--marker_type TYPE*::
  The marker type
*--observer OBSERVER*::
  The name of the observer (you).
*--rec_num NUM*::
  The receiver serial number.
*--rec_type TYPE*::
  The receiver type.
*--rec_vers VERS*::
  The receiver version.

The following options set floating point numbers that are placed in the
generated RINEX 3 obs file. They do not change how *gpsrinex* computes
anything.

*--ant_e EASTING*::
  The antenna easting from marker in meters.
*--ant_h HEIGHT*::
  The antenna height from marker in meters.
*--ant_n NORTHING*::
  The antenna northing from marker in meters.

== 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

Example 1:

Create a 4 hour .obs file. With a running *gpsd* accessible on the
localhost do all of the following, in order. Order matters.

The raw measurement messages are long. Be sure your serial port speed is
high enough:

----
gpsctl -s 115200
----

Disable all NMEA messages, and enable binary messages:

----
ubxtool -d NMEA
ubxtool -e BINARY
----

The NEO-M8N will only reliably output raw measurements when only the GPS
and QZSS constellations are enabled. If your PPP service can use
GLONASS, then enable that as well. Be sure to disable, before enable, so
as not to momentarily have too many constellations selected. *ubxtool*, as
recommended by u-blox, enables the QZSS constellation in tandem with
GPS. Disable all constellations, except GPS (and QZSS):

----
ubxtool -d BEIDOU
ubxtool -d GALILEO
ubxtool -d GLONASS
ubxtool -d SBAS
ubxtool -e GPS
----

Verify the constellations enabled:

----
ubxtool -p CFG-GNSS
----

Enable the good stuff, the raw measurement messages:

----
ubxtool -e RAWX
----

Verify raw data messages are being sent:

----
ubxtool | fgrep RAWX
----

You should see this output:

----
UBX-RXM-RAWX:
UBX-RXM-RAWX:
----

Collect 4 hours of samples at 30 second intervals, save the RINEX 3
observations in the file today.obs:

----
gpsrinex -i 30 -n 480 -f today.obs
----

Wait 4 hours. Enjoy a meal, or do some exercise. When *gpsrinex* finishes,
upload the file today.obs to your favorite PPP service.

Example 2:

Collect raw measurement data from a remote *gpsd*. Then process it later
with *gpsrinex* and *gpsprof*.

Ensure the receiver is configured properly, as shown in Example 1.

Grab 4 hours of raw live data from remote *gpsd* at 10.168.1.2:

----
gpspipe -x 14400 -R 10.168.1.2 > 4h-raw.ubx
----

When gpspipe is complete, the file 4h-raw.ubx will contain 4 hours
of raw UBX binary message.  Convert that raw data in gpsd JSON with
*gpsdecode*:

----
gpsdecode < 4h-raw.ubx > 4h-raw.json
----

The file 4h-raw.json will now contain the data encoded as gpsd JSON.
Use *gpsrinex* to read that file and create a RINEX file:

----
gpsrinex -F 4h-raw.json
----

The RINEX file will be in the current directory with the file name
like: gpsrinexYYYYjjjHHMMSS.obs

You can now use the JSON  file to generate a polar plot of the used
satellites:

----
gpsprof -f polarused -T jpeg -r < 4h-raw.json > 4h-raw.plot
gnuplot < 4h-raw.plot > 4h-raw.png
----

Use the image viewer of your choice to view your skyview in 4h-raw.png

== RETURN VALUES

*0*:: on success.
*1*:: on failure

== SEE ALSO

One service known to work with gbsrinex output is at:
https://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php

OPUS requires 2 frequency observation files.
https://www.ngs.noaa.gov/OPUS/

The curious can find the RINEX 3.04 format described here:
ftp://igs.org/pub/data/format/rinex304.pdf

*gpsd*(8), *gps*(1), *gpsprof*(1), *gpsfake*(1). *ubxtool*(1), *gpsd_json*(5)

== RESOURCES

*Project web site:* {gpsdweb}

== COPYING

This file is Copyright 2013 by the GPSD project +
SPDX-License-Identifier: BSD-2-clause
