1GPSDECODE(1) GPSD Documentation GPSDECODE(1)
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6 gpsdecode - decode GPS, RTCM or AIS streams into a readable format
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9 gpsdecode [-c] [-d] [-e] [-j] [-m] [-n] [-s] [-t typelist] [-u] [-v]
10 [-D debuglevel] [-V]
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13 This tool is a batch-mode decoder for NMEA and various binary packet
14 formats associated with GPS, AIS, and differential-correction services.
15 It produces a JSON dump on standard output from binary on standard
16 input. The JSON is the same format documented in gpsd(8); this tool
17 uses the same decoding logic as gpsd, but with a simpler interface
18 intended for batch processing of data files.
19 All sensor-input formats known to the GPSD project can be decoded by
21 this tool. These include: NMEA, AIVDM (the NMEA-derived sentence format
22 used by AIS, the marine Automatic Identification System), RTCM2, and
23 all supported GPS binary formats (notably including SiRF). See gpsd(8)
24 for applicable standards and known limitations of the decoding logic.
25 You can use this tool with nc(1) to examine AIS feeds from AIS pooling
27 services, RTCM feeds from RTCM receivers or NTRIP broadcasters.
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30 The -d option tells the program to decode packets presented on standard
31 input to standard output. This is the default behavior.
32 The -j explicitly sets the output dump format to JSON (the default
34 behavior).
35 With the -m option, dump minimum lengths for each packet type in the
37 input (ignoring comment packets). This is probably of interest only to
38 GSD developers.
39 The -n enables dumping in generated pseudo-NME0183.
41 The -e option option tells the program to encode JSON on standard input
43 to JSON on standard output. This option is only useful for
44 regression-testing of the JSON dumping and parsing code.
45 The -s option option tells the program to report AIS Type 24 sentence
47 halves separately rather than attempting to aggregate them.
48 The -t accepts a comma-separated list of numeric types. Packets with a
50 numeric AIS, RTCM2, or RTCM3 type are passed through and output only if
51 they match a type in the list. Packets of other kinds (in particular
52 GPS packets) are passed through unconditionally.
53 The -u suppresses scaling of AIS data to float quantities and text
55 expansion of numeric codes. A dump with this option is lossless.
56 The -v enables dumping of textual packets to output as they are
58 received on input, immediately preceding corresponding output.
59 The -c sets the AIS dump format to separate fields with an ASCII pipe
61 symbol. Fields are dumped in the order they occur in the AIS packet.
62 Numerics are not scaled (-u is forced). Strings are unpacked from
63 six-bit to full ASCII
64 The -V option directs the program to emit its version number, then
66 exit.
67 The -D option sets a debug verbosity level. It is mainly of interest to
69 developers.
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72 With the -c option, dump lines are values of AIS payload fields,
73 pipe-separated, in the order that they occur in the payload. Spans of
74 fields expressing a date are emitted as an ISO8601 timestamp (look for
75 colons and the trailing Z indicating Zulu/UTC time), and the 19-bit
76 group of TDMA status fields found at the end of message types 1-4 are
77 are dumped as a single unsigned integer (in hex preceded by "0x").
78 Unused regional-authority fields are also dumped (in hex preceded by
79 "0x"). Variable-length binary fields are dumped as an integer bit
80 length, followed by a colon, followed by a hex dump.
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83 gpsd(8), gpsctl(1), gpsdctl(8), gps(1), libgps(3), libgpsmm(3),
84 gpsprof(1), gpsfake(1),
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87 Eric S. Raymond <esr@thyrsus.com>.
88The GPSD Project 13 Jul 2005 GPSDECODE(1)