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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.1.2//EN"
"docbook/docbookx.dtd">
<refentry id='rtcmdecode.1'>
<refmeta>
<refentrytitle>rtcmdecode</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo class='date'>13 Jul 2005</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>rtcmdecode</refname>
<refpurpose>decode RTCM104 streams into a readable format</refpurpose>
</refnamediv>
<refsynopsisdiv id='synopsis'>
<cmdsynopsis>
<command>rtcmdecode</command>
<arg choice='opt'>-d</arg>
<arg choice='opt'>-e</arg>
<arg choice='opt'>-v <replaceable>debuglevel</replaceable></arg>
<arg choice='opt'>-V</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 id='description'><title>DESCRIPTION</title>
<para>This tool is a decoder for RTCM-104, an obscure and complicated
serial protocol used for broadcasting pseudorange corrections from
differential-GPS reference stations. RTCM-104 is expected on standard
input; an equivalent, 100%-information-preserving text format is
written to standard output.</para>
<para>You can use this tool with
<citerefentry><refentrytitle>nc</refentrytitle><manvolnum>1</manvolnum></citerefentry>
to examine RTCM feeds from DGPSIP servers or Ntrip broadcasters.</para>
<para>The decoder dump format is described in
<citerefentry><refentrytitle>rtcm</refentrytitle><manvolnum>5</manvolnum></citerefentry>;
these lines go to standard output. As well as data the decoder also
prints decoder status messages to standard error, as necessary.</para>
</refsect1>
<refsect1 id='options'><title>OPTIONS</title>
<para>The -d option tells the program to decode RTCM-104 presented on
standard input to a text dump in the format of
<citerefentry><refentrytitle>rtcm-104</refentrytitle><manvolnum>5</manvolnum></citerefentry>
on standard output. This is the default behavior.</para>
<para>The -e option option tells the program to encode a text dump in
the format of
<citerefentry><refentrytitle>rtcm-104</refentrytitle><manvolnum>5</manvolnum></citerefentry>
to standard output.</para>
<para>The -V option directs the program to emit its version number,
then exit.</para>
<para>The -v option sets a verbosity level. It is mainly of interest
to developers.</para>
</refsect1>
<refsect1 id='standard'><title>APPLICABLE STANDARDS</title>
<para>The applicable standard is
<citetitle>RTCM Recommended Standards for Differential NAVSTAR GPS
Service</citetitle> RTCM Paper 194-93/SC 104-STD.</para>
<para>Ordering instructions are accessible from the website of the
<ulink url='http://www.rtcm.org/'>Radio Technical Commission for
Maritime Services</ulink> under "Publications".</para>
</refsect1>
<refsect1 id='bugs'><title>BUGS AND LIMITATIONS</title>
<para>RTCM-104 represents floating-point quantities as an integer
multiple of a fixed scale factor. Editing an RTCM-104 dump can
produce numbers that are not an integer multiple of the scale factor
for their field. If you do this, the value actually packed into
binary RTCM-104 will be rounded down to the nearest scale unit,
and dumping will show slightly different numbers than those you
entered.</para>
<para>The decoder logic is sufficiently convoluted to confuse some
compiler optimizers, notably in GCC 3.x at -O2, into generating bad
code.</para>
</refsect1>
<refsect1 id='see_also'><title>SEE ALSO</title>
<para>
<citerefentry><refentrytitle>gpsd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gps</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>libgps</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>libgpsd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gpsprof</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gpsfake</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>rtcm-104</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
</refsect1>
<refsect1 id='maintainer'><title>AUTHOR</title>
<para>Eric S. Raymond <email>esr@thyrsus.com</email>. This is a
somewhat hacked version of an RTCM decoder originally written by
Wolfgang Rupprecht. There is a project page for
<application>gpsd</application> <ulink
url="http://gpsd.berlios.de/">here</ulink>.</para>
</refsect1>
</refentry>
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