NAME

       decode_aprs - Convert APRS raw data to human readable form.

SYNOPSIS

       decode_aprs [ text-file ]

              text-file  should  contain  AX.25 packets in the standard monitoring format.  If no
              file specified, data will be read from stdin.

DESCRIPTION

       decode_aprs is useful for understanding sometimes obscure APRS packets and finding errors.

OPTIONS

       None.

EXAMPLES

       You see something like this show up on your screen:

              M0XER-3>APRS63,WIDE2-1:!/4\;u/)K$O J]YD/A=041216|h`RY(1>q!(|

       What does it mean?  If you haven't  spent  a  lot  of  time  studying  the  APRS  protocol
       specification,  most  of it probably looks like random noise.  Pipe it into decode_aprs to
       find out.

              echo 'M0XER-3>APRS63,WIDE2-1:!/4\;u/)K$O J]YD/A=041216|h`RY(1>q!(|' | decode_aprs

       http://www.findu.com/cgi-bin/errors.cgi has a  never-ending  collection  of  packets  with
       errors.   Sometimes  it's   not   obvious what is wrong with them.  Dire Wolf will usually
       tell you what is wrong.  First, cut-n-paste the bad packets into  a  text  file.   Here  a
       couple examples:

              n2cma>APRS,TCPIP*,qAC,SEVENTH:@212127z43.2333n/77.1w_338/002g001t025P000h65b10208.wview_5_19_0

              K0YTH-10>APNU3B,NULL,qAR,K0DMF-10:!4601.5NS09255.52W#PHG6360/W2,MNn 444.575

       If   you   simply   fed  this  into decode_aprs, it would complain about the lower case in
       qA-something, added by the IGate, in the via path.  We can take it out with something like
       this:

              cat findu-errors.txt | sed -e 's/,qA.*:/:/' | decode_aprs

       In the first case, we get,

              Address has lower case letters. "n2cma" must be all upper case.

       After changing the source address to upper case, there are other issues.  Identifying them
       is left as an exercise for the reader.

       And in the second example,

              Invalid character in latitude.  Found 'N' when  expecting  0-9  for  hundredths  of
              minutes.
              Invalid  character  in  longitude.  Found '9' when expecting 0 or 1 for hundreds of
              degrees.

SEE ALSO

       More detailed information  is  in  the  pdf  files  in  /usr/local/share/doc/direwolf,  or
       possibly /usr/share/doc/direwolf, depending on installation location.

       Applications in this package: aclients, atest, decode_aprs, direwolf, gen_packets, ll2utm,
       log2gpx, text2tt, tt2text, utm2ll

                                                                                   DECODE_APRS(1)