[aprssig] Curious about bogus packets on Findu
Stephen H. Smith
wa8lmf2 at aol.com
Thu Sep 30 13:04:58 CDT 2010
On 9/30/2010 9:33 AM, Steve Noskowicz wrote:
> Noticed some error lat long locations on Findu's Long term tracking. I've not seen this before.
> I save some of these images to show with my APRS talks.
> The one in North Western Pa is early in the time period.
> The one in SE Wisconsin (and the one below the track in Illinois) is late in the trip and is probably a latitide-only glitch from one of the packets at the same longitude. I figured this out by changing the findu&start time in Steve's URL.
> However, it is difficult for me to tell looking at the raw data just which packet it is.
> I also see some raw packets with the TOCALL (APK101) instead of the Mic-e data and don't know enough to understand that.
> I couldn't see these glitches on aprs.fi.
> 73, Steve, K9DCI USN (Vet) MOT (Ret) Ham (Yet)
Some years ago this was an issue with several releases of WinAPRS running in
igate mode. The program attempted to translate Mic-E packets to plaintext APRS
format before injecting them into the Internet system. [The original reason
for the conversion was that findu wouldn't decode or process Mic-E format at
about the time the Kenwood APRS radios (which use MIc-E format exclusively)
first arrived on the APRS scene. ]
The WinAPRS conversion was buggy and would sometimes create what I dubbed
"hyper-jumps". At the time, a buggy WinAPRS igate in Southern Cal was
making my Kenwood mobile "hyperjump" constantly between Los Angeles and San
Diego, depending on which igate in the area got my packet first.
There was considerable discussion at the time on this list; it was finally
concluded that igates SHOULD NOT attempt to convert packets, but rather just
pass them as-is to the APRS-IS. (Of course, by this time Findu DID have the
capability to deal with Mic-E packets, but it took years for the bad versions
of WinAPRS to die out and be replaced.)
Even today, a few obsolete igates running bad versions of WinAPRS and aprsd are
injecting mangled Mic-E packets into the APRS-IS . (Watch Colorado east of
Denver from the APRS-IS sometime. You will see numerous Portuguese mobiles
wandering around the high plains of Colorado. This is due to a bug in a
particular version of aprsd run by a Portuguese igate, related to handling
Mic-E packets with zero or near-zero longitude values.)
Stephen H. Smith wa8lmf (at) aol.com
EchoLink Node: WA8LMF or 14400 [Think bottom of the 2M band]
Home Page: http://wa8lmf.net
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