1GPSDECODE(1)                  GPSD Documentation                  GPSDECODE(1)
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NAME

6       gpsdecode - decode GPS, RTCM or AIS streams into a readable format
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SYNOPSIS

9       gpsdecode [OPTIONS]
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11       gpsdecode -h
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13       gpsdecode -V
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DESCRIPTION

16       gpsdecode tool is a batch-mode decoder for NMEA and various binary
17       packet formats associated with GPS, AIS, and differential-correction
18       services. It produces a JSON dump on standard output from binary on
19       standard input. The JSON is the same format documented by gpsd; this
20       tool uses the same decoding logic as gpsd, but with a simpler interface
21       intended for batch processing of data files.
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23       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.
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29       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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OPTIONS

33       -?, -h, --help
34           Output a usage mssage, then exit.
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36       -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
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42       -d, --decode
43           Decode packets presented on standard input to standard output. This
44           is the default behavior.
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46       -D LVL, --debug LVL
47           Set the debug verbosity level to LVL. It is mainly of interest to
48           for troubleshooting.
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50       -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.
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55       -j, --json
56           Sets the output dump format to JSON (the default behavior).
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58       -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.
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63       -n, --nmea
64           Dump the generated pseudo-NME0183.
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66       -s, --split24
67           Report AIS Type 24 sentence halves separately rather than
68           attempting to aggregate them.
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70       -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.
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76       -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.
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80       -v, --verbose
81           Dump textual packets to output as they are received on input,
82           immediately preceding corresponding output.
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84       -V, --version
85           Print version number, then exit.
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AIS DSV FORMAT

88       With the -c or --ais option, dump lines are values of AIS payload
89       fields, pipe-separated, in the order that they occur in the payload.
90       Spans of fields expressing a date are emitted as an ISO8601 timestamp
91       (look for colons and the trailing Z indicating Zulu/UTC time), and the
92       19-bit group of TDMA status fields found at the end of message types
93       1-4 are are dumped as a single unsigned integer (in hex preceded by
94       "0x"). Unused regional-authority fields are also dumped (in hex
95       preceded by "0x"). Variable-length binary fields are dumped as an
96       integer bit length, followed by a colon, followed by a hex dump.
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RETURN VALUES

99       0
100           on success.
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102       1
103           if the action was unknown or the write to the control socket
104           failed,
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SEE ALSO

107       gpsd(8), gps(1)
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RESOURCES

110       Project web site: https://gpsd.io/
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COPYING

113       This file is Copyright 2013 by the GPSD project
114       SPDX-License-Identifier: BSD-2-clause
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AUTHOR

117       Eric S. Raymond
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121GPSD, Version 3.25                2023-01-10                      GPSDECODE(1)
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