rtcmdecode
1
13 Jul 2005
rtcmdecode
decode RTCM104 streams into a readable format
rtcmdecode
-d
-e
-v debuglevel
-V
DESCRIPTION
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.
You can use this tool with
nc1
to examine RTCM feeds from DGPSIP servers or Ntrip broadcasters.
The decoder dump format is described in
rtcm5;
these lines go to standard output. As well as data the decoder also
prints decoder status messages to standard error, as necessary.
OPTIONS
The -d option tells the program to decode RTCM-104 presented on
standard input to a text dump in the format of
rtcm-1045
on standard output. This is the default behavior.
The -e option option tells the program to encode a text dump in
the format of
rtcm-1045
to standard output.
The -V option directs the program to emit its version number,
then exit.
The -v option sets a verbosity level. It is mainly of interest
to developers.
APPLICABLE STANDARDS
The applicable standard is
RTCM Recommended Standards for Differential NAVSTAR GPS
Service RTCM Paper 194-93/SC 104-STD.
Ordering instructions are accessible from the website of the
Radio Technical Commission for
Maritime Services under "Publications".
BUGS AND LIMITATIONS
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.
The decoder logic is sufficiently convoluted to confuse some
compiler optimizers, notably in GCC 3.x at -O2, into generating bad
code.
SEE ALSO
gpsd8,
gps1,
libgps3,
libgpsd3,
gpsprof1,
gpsfake1,
rtcm-1045.
AUTHOR
Eric S. Raymond esr@thyrsus.com. This is a
somewhat hacked version of an RTCM decoder originally written by
Wolfgang Rupprecht. There is a project page for
gpsd here.