Devuan fork of gpsd
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  1. '\" t
  2. .\" Title: gpsdecode
  3. .\" Author: [see the "AUTHOR" section]
  4. .\" Generator: DocBook XSL Stylesheets v1.79.1 <>
  5. .\" Date: 13 Jul 2005
  6. .\" Manual: GPSD Documentation
  7. .\" Source: The GPSD Project
  8. .\" Language: English
  9. .\"
  10. .TH "GPSDECODE" "1" "13 Jul 2005" "The GPSD Project" "GPSD Documentation"
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  24. .nh
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  30. .SH "NAME"
  31. gpsdecode \- decode GPS, RTCM or AIS streams into a readable format
  32. .SH "SYNOPSIS"
  33. .HP \w'\fBgpsdecode\fR\ 'u
  34. \fBgpsdecode\fR [\-c] [\-d] [\-e] [\-j] [\-m] [\-n] [\-s] [\-t\ \fItypelist\fR] [\-u] [\-v] [\-D\ \fIdebuglevel\fR] [\-V]
  36. .PP
  37. 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
  38. \fBgpsd\fR(8); this tool uses the same decoding logic as gpsd, but with a simpler interface intended for batch processing of data files\&.
  39. .PP
  40. 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
  41. \fBgpsd\fR(8)
  42. for applicable standards and known limitations of the decoding logic\&.
  43. .PP
  44. You can use this tool with
  45. \fBnc\fR(1)
  46. to examine AIS feeds from AIS pooling services, RTCM feeds from RTCM receivers or NTRIP broadcasters\&.
  47. .SH "OPTIONS"
  48. .PP
  49. The
  50. \fB\-d\fR
  51. option tells the program to decode packets presented on standard input to standard output\&. This is the default behavior\&.
  52. .PP
  53. The
  54. \fB\-j\fR
  55. explicitly sets the output dump format to JSON (the default behavior)\&.
  56. .PP
  57. With the
  58. \fB\-m\fR
  59. option, dump minimum lengths for each packet type in the input (ignoring comment packets)\&. This is probably of interest only to GSD developers\&.
  60. .PP
  61. The
  62. \fB\-n\fR
  63. enables dumping in generated pseudo\-NME0183\&.
  64. .PP
  65. The
  66. \fB\-e\fR
  67. 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\&.
  68. .PP
  69. The
  70. \fB\-s\fR
  71. option option tells the program to report AIS Type 24 sentence halves separately rather than attempting to aggregate them\&.
  72. .PP
  73. The
  74. \fB\-t\fR
  75. 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\&.
  76. .PP
  77. The
  78. \fB\-u\fR
  79. suppresses scaling of AIS data to float quantities and text expansion of numeric codes\&. A dump with this option is lossless\&.
  80. .PP
  81. The
  82. \fB\-v\fR
  83. enables dumping of textual packets to output as they are received on input, immediately preceding corresponding output\&.
  84. .PP
  85. The
  86. \fB\-c\fR
  87. 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
  88. .PP
  89. The
  90. \fB\-V\fR
  91. option directs the program to emit its version number, then exit\&.
  92. .PP
  93. The
  94. \fB\-D\fR
  95. option sets a debug verbosity level\&. It is mainly of interest to developers\&.
  97. .PP
  98. With the
  99. \fB\-c\fR
  100. 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\&.
  101. .SH "SEE ALSO"
  102. .PP
  103. \fBgpsd\fR(8),
  104. \fBgpsctl\fR(1),
  105. \fBgpsdctl\fR(8),
  106. \fBgps\fR(1),
  107. \fBlibgps\fR(3),
  108. \fBlibgpsmm\fR(3),
  109. \fBgpsprof\fR(1),
  110. \fBgpsfake\fR(1),
  111. .SH "AUTHOR"
  112. .PP
  113. Eric S\&. Raymond
  114. <esr@thyrsus\&.com>\&.