Sample parsing APRS Packets with Python

w7asu-0-aprs-decoded.txt

2015-04-25 09:09:18 MST, 309
2015-04-25 09:11:17 MST, 1089
2015-04-25 09:13:16 MST, 1968
2015-04-25 09:15:16 MST, 2855
2015-04-25 09:17:16 MST, 3710
2015-04-25 09:19:16 MST, 4588
2015-04-25 09:21:15 MST, 5432
2015-04-25 09:23:15 MST, 6317
2015-04-25 09:25:15 MST, 7226
2015-04-25 09:27:14 MST, 8148
2015-04-25 09:27:15 MST, None
2015-04-25 09:29:14 MST, 9047
2015-04-25 09:31:14 MST, 9940
2015-04-25 09:33:14 MST, 10813
2015-04-25 09:35:13 MST, 11674
2015-04-25 09:37:14 MST, 12530
2015-04-25 09:39:13 MST, 13271
2015-04-25 09:41:14 MST, 14028
2015-04-25 09:43:14 MST, 14682
2015-04-25 09:45:14 MST, 15259
2015-04-25 09:47:14 MST, 15894
2015-04-25 09:49:14 MST, 16624
2015-04-25 09:51:14 MST, 17314
2015-04-25 09:53:15 MST, 18158

w7asu-0-aprs-fi.txt

2015-04-25 09:10:34 MST: W7ASU-2>S2TSXY,WIDE2-1,qAR,KE8DM:`*.FlfhO/'"<U}|!;!x||3
2015-04-25 09:12:35 MST: W7ASU-2>S2TTPY,WIDE2-1,qAR,K7ACS:`*-qn\bO/'"Ej}|!<!x||3
2015-04-25 09:16:35 MST: W7ASU-2>S2TTSR,WIDE2-1,qAR,K7ACS:`*,&m\jO/'"Y5}Byonics MT-1000|!>!x||3
2015-04-25 09:18:35 MST: W7ASU-2>S2TTUR,WIDE2-1,qAR,KE8DM:`**|nHdO/'"bn}|!?!x||3
2015-04-25 09:20:36 MST: W7ASU-2>S2TTVX,WIDE2-1,qAR,K7ACS:`*)mo*~O/'"l?}|!@!w||3
2015-04-25 09:22:36 MST: W7ASU-2>S2TTWU,WIDE2-1,qAR,K7ACS:`*(No>yO/'"ul}|!A!w||3
2015-04-25 09:22:37 MST: W7ASU-2>S2TTWU,CREBC-1*,WIDE2*,qAR,N6EAJ:`*(No>yO/'"ul}|!A!w||3<0xa9><0xdc> [Duplicate telemetry sequence, Delayed or out-of-order packet (sequence number)]
2015-04-25 09:24:36 MST: W7ASU-2>S2TUPU,WIDE2-1,qAR,K7ACS:`*'3o\gO/'#$z}Byonics MT-1000|!B!w||3
2015-04-25 09:26:37 MST: W7ASU-2>S2TURV,WIDE2-1,qAR,KC0LL-10:`*arnR_O/'#/$}|!C!w||3
2015-04-25 09:28:37 MST: W7ASU-2>S2TUVS,WIDE2-1,qAR,KD6GHX:`*`Pnz^O/'#92}|!D!v||3
2015-04-25 09:30:37 MST: W7ASU-2>S2TUXQ,WIDE2-1,qAR,KB7KFC-1:`*^vp>iO/'#Bu}|!E!v||3
2015-04-25 09:30:38 MST: W7ASU-2>S2TUXQ,CREBC-1*,WIDE2*,qAR,N6EAJ:`*^vp>iO/'#Bu}|!E!v||3R) [Duplicate telemetry sequence, Delayed or out-of-order packet (sequence number)]
2015-04-25 09:32:38 MST: W7ASU-2>S2TUYX,WIDE2-1,qAR,KE8DM:`*]/q\cO/'#M,}Byonics MT-1000|!F!v||3
2015-04-25 09:32:39 MST: W7ASU-2>S2TUYX,CREBC-1*,WIDE2*,qAR,N6EAJ:`*]/q\cO/'#M,}Byonics MT-1000|!F!v||3<0xc2>0 [Duplicate telemetry sequence, Delayed or out-of-order packet (sequence number)]
2015-04-25 09:34:38 MST: W7ASU-2>S2TVVU,WIDE2-1,qAR,KC0LL-10:`*[0pzYO/'#V+}|!G!u||3
2015-04-25 10:32:34 MST: W7ASU-2>S2TYRV,WIDE2-1,qAR,W7DXJ-3:`)@Zr mO/'#]]}|!H!p||3
2015-04-25 10:34:35 MST: W7ASU-2>S2TYWX,WIDE2-1,qAR,KE8DM:`)>Pp\qO/'#EO}|!I!q||3
2015-04-25 10:36:36 MST: W7ASU-2>S2UPQY,WIDE2-1,qAR,KE8DM:`)<wp*`O/'#/y}Byonics MT-1000|!J!q||3
2015-04-25 10:40:37 MST: W7ASU-2>S2UPYS,WIDE2-1,qAR,KC0LL-10:`):6o4`O/'"eM}|!L!p||3
2015-04-25 10:44:40 MST: W7ASU-2>S2UQUT,CHILDS,WIDE2*,qAR,KC0LL-10:`)8>m>KO/'"E6}Byonics MT-1000|!N!p||3

w7asu-2-aprs-fi.txt

2015-04-25 09:10:34 MST: W7ASU-2>S2TSXY,WIDE2-1,qAR,KE8DM:`*.FlfhO/'"<U}|!;!x||3
2015-04-25 09:12:35 MST: W7ASU-2>S2TTPY,WIDE2-1,qAR,K7ACS:`*-qn\bO/'"Ej}|!<!x||3
2015-04-25 09:16:35 MST: W7ASU-2>S2TTSR,WIDE2-1,qAR,K7ACS:`*,&m\jO/'"Y5}Byonics MT-1000|!>!x||3
2015-04-25 09:18:35 MST: W7ASU-2>S2TTUR,WIDE2-1,qAR,KE8DM:`**|nHdO/'"bn}|!?!x||3
2015-04-25 09:20:36 MST: W7ASU-2>S2TTVX,WIDE2-1,qAR,K7ACS:`*)mo*~O/'"l?}|!@!w||3
2015-04-25 09:22:36 MST: W7ASU-2>S2TTWU,WIDE2-1,qAR,K7ACS:`*(No>yO/'"ul}|!A!w||3
2015-04-25 09:24:36 MST: W7ASU-2>S2TUPU,WIDE2-1,qAR,K7ACS:`*'3o\gO/'#$z}Byonics MT-1000|!B!w||3
2015-04-25 09:26:37 MST: W7ASU-2>S2TURV,WIDE2-1,qAR,KC0LL-10:`*arnR_O/'#/$}|!C!w||3
2015-04-25 09:28:37 MST: W7ASU-2>S2TUVS,WIDE2-1,qAR,KD6GHX:`*`Pnz^O/'#92}|!D!v||3
2015-04-25 09:30:37 MST: W7ASU-2>S2TUXQ,WIDE2-1,qAR,KB7KFC-1:`*^vp>iO/'#Bu}|!E!v||3
2015-04-25 09:32:38 MST: W7ASU-2>S2TUYX,WIDE2-1,qAR,KE8DM:`*]/q\cO/'#M,}Byonics MT-1000|!F!v||3
2015-04-25 09:34:38 MST: W7ASU-2>S2TVVU,WIDE2-1,qAR,KC0LL-10:`*[0pzYO/'#V+}|!G!u||3
2015-04-25 10:32:34 MST: W7ASU-2>S2TYRV,WIDE2-1,qAR,W7DXJ-3:`)@Zr mO/'#]]}|!H!p||3
2015-04-25 10:34:35 MST: W7ASU-2>S2TYWX,WIDE2-1,qAR,KE8DM:`)>Pp\qO/'#EO}|!I!q||3
2015-04-25 10:36:36 MST: W7ASU-2>S2UPQY,WIDE2-1,qAR,KE8DM:`)<wp*`O/'#/y}Byonics MT-1000|!J!q||3
2015-04-25 10:40:37 MST: W7ASU-2>S2UPYS,WIDE2-1,qAR,KC0LL-10:`):6o4`O/'"eM}|!L!p||3
2015-04-25 10:44:40 MST: W7ASU-2>S2UQUT,CHILDS,WIDE2*,qAR,KC0LL-10:`)8>m>KO/'"E6}Byonics MT-1000|!N!p||3

w7asu-2-decoded.txt

2015-04-25 09:10:34 MST, 790
2015-04-25 09:12:35 MST, 1630
2015-04-25 09:16:35 MST, 3397
2015-04-25 09:18:35 MST, 4273
2015-04-25 09:20:36 MST, 5136
2015-04-25 09:22:36 MST, 6000
2015-04-25 09:24:36 MST, 6924
2015-04-25 09:26:37 MST, 7839
2015-04-25 09:28:37 MST, 8763
2015-04-25 09:30:37 MST, 9649
2015-04-25 09:32:38 MST, 10577
2015-04-25 09:34:38 MST, 11395
2015-04-25 10:32:34 MST, 12082
2015-04-25 10:34:35 MST, 9884
2015-04-25 10:36:36 MST, 7924
2015-04-25 10:40:37 MST, 4513
2015-04-25 10:44:40 MST, 1578

w7asu-parse.py

import aprslib


def main(infile):
    """docstring for main"""
    with open(infile) as f:
        for line in f:
            timestamp = line[:23]
            aprs_packet = line[24:].strip()
            try:
                aprs_data = aprslib.parse(aprs_packet)
                print "%s, %s" % (timestamp, aprs_data.get('altitude', None))
            except (aprslib.ParseError, aprslib.UnknownFormat) as exp:
                #print aprs_packet
                pass


if __name__ == '__main__':
    import sys
    main(sys.argv[1])

I grabbed the raw packets from http://aprs.fi for both W7ASU-0 and W7ASU-2, cleaned up the duplicate and bad packets and saved them in the files: w7asu-0-aprs-fi.txt and w7asu-2-aprs-fi.txt.

Then I wrote the w7asu-parse.py, which parses those files to generate the w7asu-2-decoded.txt and w7asu-2-decoded.txt output files, which are just timestamp followed by the altitude in meters. I will plot these at some point.