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 [-?] [--ais] [--decode] [--debug LVL] [--encode] [--help]
10 [--json] [--minlength] [--nmea] [--split24]
11 [--types typelist] [--unscaled] [--verbose] [--version] [-c]
12 [-d] [-D LVL] [-e] [-h] [-j] [-m] [-n] [-s] [-t typelist]
13 [-u] [-v] [-V]
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16 This tool is a batch-mode decoder for NMEA and various binary packet
17 formats associated with GPS, AIS, and differential-correction services.
18 It produces a JSON dump on standard output from binary on standard
19 input. The JSON is the same format documented in gpsd(8); this tool
20 uses the same decoding logic as gpsd, but with a simpler interface
21 intended for batch processing of data files.
22 All sensor-input formats known to the GPSD project can be decoded by
24 this tool. These include: NMEA, AIVDM (the NMEA-derived sentence format
25 used by AIS, the marine Automatic Identification System), RTCM2, and
26 all supported GPS binary formats (notably including SiRF). See gpsd(8)
27 for applicable standards and known limitations of the decoding logic.
28 You can use this tool with nc(1) to examine AIS feeds from AIS pooling
30 services, RTCM feeds from RTCM receivers or NTRIP broadcasters.
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33 -?, -h, --help
34 Output a usage mssage, then exit.
35 -c, --json
37 Sets the AIS dump format to separate fields with an ASCII pipe
38 symbol. Fields are dumped in the order they occur in the AIS
39 packet. Numerics are not scaled (-u is forced). Strings are
40 unpacked from six-bit to full ASCII
41 -d, --decode
43 Decode packets presented on standard input to standard output. This
44 is the default behavior.
45 -D LVL, --debug LVL
47 Set the debug verbosity level to LVL. It is mainly of interest to
48 for troubleshooting.
49 -e, --encode
51 Encode JSON on standard input to JSON on standard output. This
52 option is only useful for regression-testing of the JSON dumping
53 and parsing code.
54 -j, --json
56 Sets the output dump format to JSON (the default behavior).
57 -m, --minlength
59 Dump minimum lengths for each packet type in the input (ignoring
60 comment packets). This is probably of interest only to GSD
61 developers.
62 -n, --nmea
64 Dump the generated pseudo-NME0183.
65 -s, --split24
67 Report AIS Type 24 sentence halves separately rather than
68 attempting to aggregate them.
69 -t TYPES, --types TYPES
71 A comma-separated list of numeric types. Packets with a numeric
72 AIS, RTCM2, or RTCM3 type are passed through and output only if
73 they match a type in the list. Packets of other kinds (in
74 particular GPS packets) are passed through unconditionally.
75 -u, --unsscaled
77 Suppress scaling of AIS data to float quantities and text expansion
78 of numeric codes. A dump with this option is lossless.
79 -v, --verbose
81 Dump textual packets to output as they are received on input,
82 immediately preceding corresponding output.
83 -V, --version
85 Print version number, then exit.
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88 With the -c, --ais option, dump lines are values of AIS payload fields,
89 pipe-separated, in the order that they occur in the payload. Spans of
90 fields expressing a date are emitted as an ISO8601 timestamp (look for
91 colons and the trailing Z indicating Zulu/UTC time), and the 19-bit
92 group of TDMA status fields found at the end of message types 1-4 are
93 are dumped as a single unsigned integer (in hex preceded by "0x").
94 Unused regional-authority fields are also dumped (in hex preceded by
95 "0x"). Variable-length binary fields are dumped as an integer bit
96 length, followed by a colon, followed by a hex dump.
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99 gpsd(8), gpsctl(1), gpsdctl(8), gps(1), libgps(3), libgpsmm(3),
100 gpsprof(1), gpsfake(1),
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103 Eric S. Raymond <esr@thyrsus.com>.
104The GPSD Project 6 December 2020 GPSDECODE(1)