gpsdecode(1) GPSD Documentation gpsdecode(1)
NAME
gpsdecode - decode GPS, RTCM or AIS streams into a readable format
SYNOPSIS
gpsdecode [-?] [--ais] [--decode] [--debug LVL] [--encode] [--help]
[--json] [--minlength] [--nmea] [--split24]
[--types typelist] [--unscaled] [--verbose] [--version] [-c]
[-d] [-D LVL] [-e] [-h] [-j] [-m] [-n] [-s] [-t typelist]
[-u] [-v] [-V]
DESCRIPTION
This 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 in gpsd(8); 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, --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.
SEE ALSO
gpsd(8), gpsctl(1), gpsdctl(8), gps(1), libgps(3), libgpsmm(3),
gpsprof(1), gpsfake(1),
AUTHOR
Eric S. Raymond <esr@thyrsus.com>.
The GPSD Project 6 December 2020 gpsdecode(1)
gpsd 3.22 - Generated Sat Jan 16 11:30:30 CST 2021