Devuan fork of gpsd
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  1. <?xml version="1.0" encoding="ISO-8859-1"?>
  2. <!--
  3. This file is Copyright (c) 2010 by the GPSD project
  4. SPDX-License-Identifier: BSD-2-clause
  5. -->
  6. <!DOCTYPE refentry PUBLIC
  7. "-//OASIS//DTD DocBook XML V4.1.2//EN"
  8. "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
  9. <refentry id='gpsdecode.1'>
  10. <refentryinfo><date>13 Jul 2005</date></refentryinfo>
  11. <refmeta>
  12. <refentrytitle>gpsdecode</refentrytitle>
  13. <manvolnum>1</manvolnum>
  14. <refmiscinfo class="source">The GPSD Project</refmiscinfo>
  15. <refmiscinfo class="manual">GPSD Documentation</refmiscinfo>
  16. </refmeta>
  17. <refnamediv id='name'>
  18. <refname>gpsdecode</refname>
  19. <refpurpose>decode GPS, RTCM or AIS streams into a readable format</refpurpose>
  20. </refnamediv>
  21. <refsynopsisdiv id='synopsis'>
  22. <cmdsynopsis>
  23. <command>gpsdecode</command>
  24. <arg choice='opt'>-c</arg>
  25. <arg choice='opt'>-d</arg>
  26. <arg choice='opt'>-e</arg>
  27. <arg choice='opt'>-j</arg>
  28. <arg choice='opt'>-m</arg>
  29. <arg choice='opt'>-n</arg>
  30. <arg choice='opt'>-s</arg>
  31. <arg choice='opt'>-t <replaceable>typelist</replaceable></arg>
  32. <arg choice='opt'>-u</arg>
  33. <arg choice='opt'>-v</arg>
  34. <arg choice='opt'>-D <replaceable>debuglevel</replaceable></arg>
  35. <arg choice='opt'>-V</arg>
  36. </cmdsynopsis>
  37. </refsynopsisdiv>
  38. <refsect1 id='description'><title>DESCRIPTION</title>
  39. <para>This tool is a batch-mode decoder for NMEA and various binary
  40. packet formats associated with GPS, AIS, and differential-correction
  41. services. It produces a JSON dump on standard output from binary on
  42. standard input. The JSON is the same format documented in
  43. <citerefentry><refentrytitle>gpsd</refentrytitle><manvolnum>8</manvolnum></citerefentry>;
  44. this tool uses the same decoding logic as gpsd, but with a simpler
  45. interface intended for batch processing of data files.</para>
  46. <para>All sensor-input formats known to the GPSD project can be
  47. decoded by this tool. These include: NMEA, AIVDM (the NMEA-derived
  48. sentence format used by AIS, the marine Automatic Identification
  49. System), RTCM2, and all supported GPS binary formats (notably
  50. including SiRF). See
  51. <citerefentry><refentrytitle>gpsd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  52. for applicable standards and known limitations of the decoding
  53. logic.</para>
  54. <para>You can use this tool with
  55. <citerefentry><refentrytitle>nc</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  56. to examine AIS feeds from AIS pooling services, RTCM feeds from RTCM
  57. receivers or NTRIP broadcasters.</para>
  58. </refsect1>
  59. <refsect1 id='options'><title>OPTIONS</title>
  60. <para>The <option>-d</option> option tells the program to decode
  61. packets presented on standard input to standard output. This is the
  62. default behavior.</para>
  63. <para>The <option>-j</option> explicitly sets the output dump format
  64. to JSON (the default behavior).</para>
  65. <para>With the <option>-m</option> option, dump minimum lengths for
  66. each packet type in the input (ignoring comment packets). This is
  67. probably of interest only to GSD developers.</para>
  68. <para>The <option>-n</option> enables dumping in generated
  69. pseudo-NME0183.</para>
  70. <para>The <option>-e</option> option option tells the program to
  71. encode JSON on standard input to JSON on standard output. This option
  72. is only useful for regression-testing of the JSON dumping and parsing
  73. code.</para>
  74. <para>The <option>-s</option> option option tells the program to report
  75. AIS Type 24 sentence halves separately rather than attempting to
  76. aggregate them.</para>
  77. <para>The <option>-t</option> accepts a comma-separated list of
  78. numeric types. Packets with a numeric AIS, RTCM2, or RTCM3 type are
  79. passed through and output only if they match a type in the
  80. list. Packets of other kinds (in particular GPS packets) are
  81. passed through unconditionally.</para>
  82. <para>The <option>-u</option> suppresses scaling of AIS data to float
  83. quantities and text expansion of numeric codes. A dump with this
  84. option is lossless.</para>
  85. <para>The <option>-v</option> enables dumping of textual packets
  86. to output as they are received on input, immediately preceding
  87. corresponding output.</para>
  88. <para>The <option>-c</option> sets the AIS dump format to separate
  89. fields with an ASCII pipe symbol. Fields are dumped in the order they
  90. occur in the AIS packet. Numerics are not scaled (-u is
  91. forced). Strings are unpacked from six-bit to full ASCII</para>
  92. <para>The <option>-V</option> option directs the program to emit its
  93. version number, then exit.</para>
  94. <para>The <option>-D</option> option sets a debug verbosity level. It is
  95. mainly of interest to developers.</para>
  96. </refsect1>
  97. <refsect1 id='json_ais'><title>AIS DSV FORMAT</title>
  98. <para>With the <option>-c</option> option, dump lines are values of AIS
  99. payload fields, pipe-separated, in the order that they occur in the
  100. payload. Spans of fields expressing a date are emitted as an ISO8601
  101. timestamp (look for colons and the trailing Z indicating Zulu/UTC
  102. time), and the 19-bit group of TDMA status fields found at the end of
  103. message types 1-4 are are dumped as a single unsigned integer (in hex
  104. preceded by "0x"). Unused regional-authority fields are also dumped
  105. (in hex preceded by "0x"). Variable-length binary fields are dumped as
  106. an integer bit length, followed by a colon, followed by a hex
  107. dump.</para>
  108. </refsect1>
  109. <refsect1 id='see_also'><title>SEE ALSO</title>
  110. <para>
  111. <citerefentry><refentrytitle>gpsd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  112. <citerefentry><refentrytitle>gpsctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  113. <citerefentry><refentrytitle>gpsdctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  114. <citerefentry><refentrytitle>gps</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  115. <citerefentry><refentrytitle>libgps</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  116. <citerefentry><refentrytitle>libgpsmm</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  117. <citerefentry><refentrytitle>gpsprof</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  118. <citerefentry><refentrytitle>gpsfake</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  119. </para>
  120. </refsect1>
  121. <refsect1 id='maintainer'><title>AUTHOR</title>
  122. <para>Eric S. Raymond <email>esr@thyrsus.com</email>.</para>
  123. </refsect1>
  124. </refentry>