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 [-c] [-d] [-e] [-j] [-m] [-n] [-s] [-t typelist] [-u] [-v]
10                 [-D debuglevel] [-V]
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DESCRIPTION

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.
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20       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.
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26       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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OPTIONS

30       The -d option tells the program to decode packets presented on standard
31       input to standard output. This is the default behavior.
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33       The -j explicitly sets the output dump format to JSON (the default
34       behavior).
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36       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.
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40       The -n enables dumping in generated pseudo-NME0183.
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42       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.
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46       The -s option option tells the program to report AIS Type 24 sentence
47       halves separately rather than attempting to aggregate them.
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49       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.
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54       The -u suppresses scaling of AIS data to float quantities and text
55       expansion of numeric codes. A dump with this option is lossless.
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57       The -v enables dumping of textual packets to output as they are
58       received on input, immediately preceding corresponding output.
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60       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
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65       The -V option directs the program to emit its version number, then
66       exit.
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68       The -D option sets a debug verbosity level. It is mainly of interest to
69       developers.
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AIS DSV FORMAT

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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SEE ALSO

83       gpsd(8), gpsctl(1), gpsdctl(8), gps(1), libgps(3), libgpsmm(3),
84       gpsprof(1), gpsfake(1),
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AUTHOR

87       Eric S. Raymond <esr@thyrsus.com>.
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91The GPSD Project                  13 Jul 2005                     GPSDECODE(1)
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