mirror of https://github.com/wb2osz/direwolf.git
102 lines
2.8 KiB
Groff
102 lines
2.8 KiB
Groff
.TH DECODE_APRS 1
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.SH NAME
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decode_aprs \- Convert APRS raw data to human readable form.
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.SH SYNOPSIS
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.B decode_aprs
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[ \fItext-file\fR ]
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.RS
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.P
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\fItext-file\fR should contain AX.25 packets in the standard monitoring format or
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as a series two digit hexadecimal numbers.
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If the first number is 00 or c0, it will be treated as a KISS frame.
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If no file specified, data will be read from stdin.
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.P
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.RE
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.SH DESCRIPTION
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\fBdecode_aprs\fR is useful for understanding sometimes obscure APRS packets and finding errors.
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.SH OPTIONS
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None.
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.SH EXAMPLES
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You see something like this show up on your screen:
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.P
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.RS
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M0XER-3>APRS63,WIDE2-1:!/4\\;u/)K$O J]YD/A=041216|h`RY(1>q!(|
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.RE
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.P
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What does it mean? If you haven't spent a lot of time studying the APRS protocol
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specification, most of it probably looks like random noise.
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Pipe it into decode_aprs to find out.
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.P
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.RS
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.B echo 'M0XER-3>APRS63,WIDE2-1:!/4\\\\;u/)K$O J]YD/A=041216|h`RY(1>q!(|' | decode_aprs
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.RE
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.P
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http://www.findu.com/cgi-bin/errors.cgi has a never-ending collection of packets
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with errors. Sometimes it's not obvious what is wrong with them.
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Dire Wolf will usually tell you what is wrong. First,
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cut-n-paste the bad packets into a text file. Here a few examples:
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.P
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.RS
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n2cma>APRS,TCPIP*,qAC,SEVENTH:@212127z43.2333n/77.1w_338/002g001t025P000h65b10208.wview_5_19_0
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.P
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K0YTH-10>APNU3B,NULL,qAR,K0DMF-10:!4601.5NS09255.52W#PHG6360/W2,MNn 444.575
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.P
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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
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.RE
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.P
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If you simply fed this into decode_aprs, it would complain about the
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lower case in qA-something, added by the IGate, in the via path.
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We can take it out with something like this:
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.P
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.RS
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.B cat findu-errors.txt | sed -e 's/,qA.*:/:/' | decode_aprs
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.RE
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.P
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In the first case, we get,
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.P
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.RS
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Address has lower case letters. "n2cma" must be all upper case.
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.RE
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.P
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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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.P
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In the second example,
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.P
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.RS
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.PD 0
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Invalid character in latitude. Found 'N' when expecting 0-9 for hundredths of minutes.
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.P
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Invalid character in longitude. Found '9' when expecting 0 or 1 for hundreds of degrees.
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.PD
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.RE
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.P
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In the third example,
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.P
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.RS
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.PD 0
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Warning: Lower case letter in Maidenhead locator. Specification requires upper case.
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.P
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Digi2 Address, " WIDE2-1" contains character other than letter or digit in character position 1.
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.PD
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.RE
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.SH SEE ALSO
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More detailed information is in the pdf files in /usr/local/share/doc/direwolf, or possibly /usr/share/doc/direwolf, depending on installation location.
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Applications in this package: aclients, atest, decode_aprs, direwolf, gen_packets, ll2utm, log2gpx, text2tt, tt2text, utm2ll
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