1DECODE_APRS(1)              General Commands Manual             DECODE_APRS(1)
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NAME

6       decode_aprs - Convert APRS raw data to human readable form.
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SYNOPSIS

11       decode_aprs [ text-file ]
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13              text-file  should contain AX.25 packets in the standard monitor‐
14              ing format or as a series two digit hexadecimal numbers.  If the
15              first  number  is  00 or c0, it will be treated as a KISS frame.
16              If no file specified, data will be read from stdin.
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DESCRIPTION

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

25       None.
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EXAMPLES

31       You see something like this show up on your screen:
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33              M0XER-3>APRS63,WIDE2-1:!/4\;u/)K$O J]YD/A=041216|h`RY(1>q!(|
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35       What  does  it  mean?   If you haven't spent a lot of time studying the
36       APRS protocol specification, most of  it  probably  looks  like  random
37       noise.  Pipe it into decode_aprs to find out.
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39              echo                         'M0XER-3>APRS63,WIDE2-1:!/4\;u/)K$O
40              J]YD/A=041216|h`RY(1>q!(|' | decode_aprs
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42       http://www.findu.com/cgi-bin/errors.cgi has a  never-ending  collection
43       of  packets  with  errors.   Sometimes it's  not  obvious what is wrong
44       with them.  Dire Wolf will usually tell you what is wrong.  First, cut-
45       n-paste the bad packets into a text file.  Here a few examples:
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47              n2cma>APRS,TCPIP*,qAC,SEVENTH:@212127z43.2333n/77.1w_338/002g001t025P000h65b10208.wview_5_19_0
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49              K0YTH-10>APNU3B,NULL,qAR,K0DMF-10:!4601.5NS09255.52W#PHG6360/W2,MNn 444.575
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51              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
52              +.fi
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54       If  you  simply  fed  this  into decode_aprs, it would complain about the
55       lower case in qA-something, added by the IGate, in the via path.
56       We can take it out with something like this:
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58              cat findu-errors.txt | sed -e 's/,qA.*:/:/' | decode_aprs
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60       In the first case, we get,
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62              Address has lower case letters. "n2cma" must be all upper case.
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64       After changing the source address to upper case, there are other issues.  Identifying them is left as an exercise for the reader.
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66       In the second example,
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68              Invalid character in latitude.  Found 'N' when expecting 0-9 for hundredths of minutes.
69              Invalid character in longitude.  Found '9' when expecting 0 or 1 for hundreds of degrees.
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72       In the third example,
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74              Warning: Lower case letter in Maidenhead locator.  Specification requires upper case.
75              Digi2 Address, " WIDE2-1" contains character other than letter or digit in character position 1.
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SEE ALSO

81       More    detailed    information    is    in    the    pdf    files   in
82       /usr/local/share/doc/direwolf,  or  possibly   /usr/share/doc/direwolf,
83       depending on installation location.
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85       Applications  in  this package: aclients, atest, decode_aprs, direwolf,
86       gen_packets, ll2utm, log2gpx, text2tt, tt2text, utm2ll
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91                                                                DECODE_APRS(1)
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