There is a popular flavor of Linux/APRSD that can not gate any Mic-E coded beacon with a longitude of nine degrees. In the Mic-E encoding a "9" is encoded as the DEL character (ASCII 127). This particular APRSD flavor automatically replaces the DEL character by a SPACE character (ASCII 32) in the gated beacon. The longitude then decodes to 104 degrees. The station icon consequently appears in Asia, or Colorado for the -9 to -104 degrees corruption.
The massive mangling of Mic-E coded stations from Germany and northern Italy has nearly dissappeared, however, IZ7BOJ-11, HG1PXX-11, OK1KYU-14, pe1oez-12 and S53DXX-2 are still misplacing Mic-E stations from 9 to 104 degrees longitude. S53DXX-2 also appears in my invalid Mic-E beacons log because it drops bytes and mangles the symbol. At the western side of Europe the IGATE CS1SEL misplaces all Mic-E coded Portuguese stations with a longitude of -9 degrees to -104 degrees (Colorado, USA).
The same happens at a longitude of 99 degress and you can see APRS icons of US stations misplaced from -99 degrees to -4 degrees (in Europe or Africa). WB5AOH cares for the mangling.
In contrast to the other frequent bug of the APRSD IGATEs to drop the FS byte (ASCII 28) from the gated Mic-E, this gated beacon remains valid and can not easily be discarded. It does not appear in my "Invalid Mic-E Beacons Log Statistics", because the symbols remain unchanged.
To illustrate the problem I made a page with an online decoder for the raw findu.com log. If you see a corrupted Mic-E position beacon you can see what had happened in the decoded log of the last 24 hours at
http://f5vag.eu/24h/<the station's callsign>.
The most right column of the table shows the ASCII values of the Data Type Identifier and the eight Mic-E bytes. A link to the decoded log is provided below the maps on my UI-WebServer.
Some examples from my archive to document the problem:
CT2IIT-9 driving in Lisbon, Portugal | ||
SP9UUC-9 driving in northern Italy | ||
DB7OZ-5 driving in northern Germany | ||
DO3MHA-9 driving in southern Germany | ||
DO2FAH-9 in southern Germany | ||
K5MNM driving in Texas |
How to test your IGATE?
Use a Mic-E generator (i.e. tracker, TH-D7 or TM-D700) and program it for the test to a longitude of 9.0 degrees (009.00.00) East or West. Test your own IGATE by gating that beacon. Then turn your IGATE off for a moment to test other IGATEs in reach of your beacon. If you see your beacon gated to a longitude of 104 degrees or your symbol mangled, the gating IGATE has a problem. You should let the sysop know about this bug.
All this dumping and replacing of bytes by the APRSD IGATEs creates false duplicates on the APRS-IS which will not be trapped by the dupe check. It is a useless waste of bandwidth.
© F5VAG, 2006/7
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It was last modified 2008-Jan-23 09:22:10 UTC