gpsdecode(1) GPSD Documentation gpsdecode(1)
NAME
gpsdecode - decode GPS, RTCM or AIS streams into a readable format
SYNOPSIS
gpsdecode [OPTIONS]
gpsdecode -h
gpsdecode -V
DESCRIPTION
gpsdecode tool is a batch-mode decoder for NMEA and various binary packet
formats associated with GPS, AIS, and differential-correction services.
It produces a JSON dump on standard output from binary on standard input.
The JSON is the same format documented by gpsd; this tool uses the same
decoding logic as gpsd, but with a simpler interface intended for batch
processing of data files.
All sensor-input formats known to the GPSD project can be decoded by this
tool. These include: NMEA, AIVDM (the NMEA-derived sentence format used
by AIS, the marine Automatic Identification System), RTCM2, and all
supported GPS binary formats (notably including SiRF). See gpsd(8) for
applicable standards and known limitations of the decoding logic.
You can use this tool with nc(1) to examine AIS feeds from AIS pooling
services, RTCM feeds from RTCM receivers or NTRIP broadcasters.
OPTIONS
-?, -h, --help
Output a usage mssage, then exit.
-c, --json
Sets the AIS dump format to separate fields with an ASCII pipe
symbol. Fields are dumped in the order they occur in the AIS packet.
Numerics are not scaled (-u is forced). Strings are unpacked from
six-bit to full ASCII
-d, --decode
Decode packets presented on standard input to standard output. This
is the default behavior.
-D LVL, --debug LVL
Set the debug verbosity level to LVL. It is mainly of interest to for
troubleshooting.
-e, --encode
Encode JSON on standard input to JSON on standard output. This option
is only useful for regression-testing of the JSON dumping and parsing
code.
-j, --json
Sets the output dump format to JSON (the default behavior).
-m, --minlength
Dump minimum lengths for each packet type in the input (ignoring
comment packets). This is probably of interest only to GSD
developers.
-n, --nmea
Dump the generated pseudo-NME0183.
-s, --split24
Report AIS Type 24 sentence halves separately rather than attempting
to aggregate them.
-t TYPES, --types TYPES
A comma-separated list of numeric types. Packets with a numeric AIS,
RTCM2, or RTCM3 type are passed through and output only if they match
a type in the list. Packets of other kinds (in particular GPS
packets) are passed through unconditionally.
-u, --unsscaled
Suppress scaling of AIS data to float quantities and text expansion
of numeric codes. A dump with this option is lossless.
-v, --verbose
Dump textual packets to output as they are received on input,
immediately preceding corresponding output.
-V, --version
Print version number, then exit.
AIS DSV FORMAT
With the -c or --ais option, dump lines are values of AIS payload fields,
pipe-separated, in the order that they occur in the payload. Spans of
fields expressing a date are emitted as an ISO8601 timestamp (look for
colons and the trailing Z indicating Zulu/UTC time), and the 19-bit group
of TDMA status fields found at the end of message types 1-4 are are
dumped as a single unsigned integer (in hex preceded by "0x"). Unused
regional-authority fields are also dumped (in hex preceded by "0x").
Variable-length binary fields are dumped as an integer bit length,
followed by a colon, followed by a hex dump.
RETURN VALUES
0
on success.
1
if the action was unknown or the write to the control socket failed,
SEE ALSO
gpsd(8), gps(1)
RESOURCES
Project web site: <https://gpsd.io/>
COPYING
This file is Copyright 2013 by the GPSD project
SPDX-License-Identifier: BSD-2-clause
AUTHOR
Eric S. Raymond
GPSD, Version 3.24 2021-09-20 gpsdecode(1)
mgpsd 3.24 - Generated Sun Jan 1 11:04:38 CST 2023