Provided by: gpsd-clients_2.37-4_i386 bug


       rtcmdecode - decode RTCM104 streams into a readable format


       rtcmdecode [-d] [-e] [-v debuglevel] [-V]


       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 nc(1) to examine RTCM feeds from DGPSIP
       servers or Ntrip broadcasters.

       The decoder dump format is described in rtcm(5); these lines go to
       standard output. As well as data the decoder also prints decoder status
       messages to standard error, as necessary.


       The -d option tells the program to decode RTCM-104 presented on
       standard input to a text dump in the format of rtcm-104(5) 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-104(5) to standard output.

       The -V option directs the program to emit its version number, then

       The -v option sets a verbosity level. It is mainly of interest to


       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[1] under "Publications".


       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.


       gpsd(8), cgps(1), libgps(3), libgpsd(3), gpsprof(1), gpsfake(1),


       Eric S. Raymond <>. This is a somewhat hacked version of
       an RTCM decoder originally written by Wolfgang Rupprecht. There is a
       project page for gpsd here[2].


        1. Radio Technical Commission for Maritime Services

        2. here