GPSDECODE(1) GPSD Documentation GPSDECODE(1)NAMEgpsdecode - decode GPS, RTCM or AIS streams into a readable format
SYNOPSISgpsdecode [-c] [-d] [-e] [-j] [-t typelist] [-u] [-v] [-D debuglevel]
[-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
The -d option tells the program to decode packets presented on standard
input to standard output. This is the default behavior.
The -j explicitly sets the output dump format to JSON (the default
behavior).
The -e option option tells the program to 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.
The -t accepts 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.
The -u suppresses scaling of AIS data to float quantities and text
expansion of numeric codes. A dump with this option is lossless.
The -v enables dumping of textual packets to output as they are
received on input, immediately preceding corresponding output.
The -c 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
The -V option directs the program to emit its version number, then
exit.
The -D option sets a debug verbosity level. It is mainly of interest to
developers.
AIS DSV FORMAT
With the -c 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 ALSOgpsd(8), gpsctl(1), gpsdctl(8), gps(1), libgps(3), libgpsd(3),
gpsprof(1), gpsfake(1),
AUTHOR
Eric S. Raymond <esr@thyrsus.com>.
The GPSD Project 13 Jul 2005 GPSDECODE(1)
