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 or as a
              series two digit hexadecimal numbers.  If the first number is 00 or c0, it will  be
              treated as a KISS frame.  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 few
       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

              00 82 a0 ae ae 62 60 e0 82 96 68 84 40 40 60 9c 68 b0 ae 86 40 e0 40 ae 92 88 8a 64 63 03 f0 3e 45 4d 36 34 6e 65 2f 23 20 45 63 68 6f 6c 69 6e 6b 20 31 34 35 2e 33 31 30 2f 31 30 30 68 7a 20 54 6f 6e 65
              +.fi

       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.

       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.

       In the third example,

              Warning: Lower case letter in Maidenhead locator.  Specification requires upper case.
              Digi2 Address, " WIDE2-1" contains character other than letter or digit in character position 1.

SEE ALSO

       More      detailed      information      is      in      the      PDF       files       at
       https://github.com/wb2osz/direwolf/tree/master/doc/.

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

                                                                                   DECODE_APRS(1)