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[aprssig] emergency beacon called wide1-1 today

Bob Bruninga bruninga at usna.edu
Sun Mar 15 02:50:48 UTC 2009


>  Is this a matter of confusing two different 
> stations because of the mangled Mic-E 
> Latitude (Destination address field) data 
> - that "looks" like the N-number ?  Huh?

Yes, I have been watching this, but since I did not have a copy of the SPEC with me, I did not want to weigh-in until I checked with the spec.  But yes, N789PH can be a perfectly valid MIC-E TOCALL, but then it would be a miracle if it actually matched a real TAIL number AND a tail number with a HAM OWNER... which it appears to do.

But as someone else pointed out, the N is not a valid Mic-E byte either.  SO it would hae to be a one in several million conicidence of a mangled packet and all of the above.

BUT, now I can see a possibility, and that is that the software that is calling this an EMERGENCY packet is ignoring the fact that the "N" is not valid, and treating it as a valid message bit, and then interprets it wrongly as part of of an emergency message.

Again, I have only looked at this in passing, but Steve is ont he right track.

Bob, WB4APR


>My brain hurts.
>--
>73, Steve, K9DCI
>You know that sea of entropy we were going to drown in?  Well, upon closer examination, it turned out to be ignorance.  S. Noskowicz 1987
>
>
>--- On Sat, 3/14/09, Rusty Hemenway <nnn0fjk at gmail.com> wrote:
>
>> From: Rusty Hemenway <nnn0fjk at gmail.com>
>> Subject: Re: [aprssig] emergency beacon called wide1-1 today
>> To: "'TAPR APRS Mailing List'" <aprssig at tapr.org>
>> Date: Saturday, March 14, 2009, 8:21 PM
>> Is there someone in the area that can give him a call and
>> help him set it up
>> correctly? 
>> 
>>  
>> 
>> From: aprssig-bounces at tapr.org
>> [mailto:aprssig-bounces at tapr.org] On Behalf
>> Of Greg D.
>> Sent: Saturday, March 14, 2009 5:43 PM
>> To: aprssig at tapr.org
>> Subject: Re: [aprssig] emergency beacon called wide1-1
>> today
>> 
>>  
>> 
>> Last position (about 30 min ago) shows the plane in front
>> of the hangar at
>> the Anoka County airport.  Presumably he'll be home
>> soon.  Google says it's
>> about a 20 minute commute.
>> 
>> Greg  KO6TH
>> 
>> 
>> > From: ve7gdh at rac.ca
>> > To: aprssig at tapr.org
>> > Date: Sat, 14 Mar 2009 13:17:29 -0700
>> > Subject: Re: [aprssig] emergency beacon called wide1-1
>> today
>> > 
>> > Chuck W3YNI wrote...
>> > 
>> > Subject: Re: [aprssig] emergency beacon called wide1-1
>> today
>> > 
>> > > Actually spoke to some folks from CAP. Gave them
>> what I believed
>> > > was the tailnumber at the time (now confirmed)
>> along with last known
>> > > coordinates from the beacon.
>> > >
>> > > Guy I spoke to is a ham and knew what APRS is -
>> he sent it up the
>> > > chain.
>> > 
>> > and posted by Rusty (K1GGS?)...
>> > 
>> > >
>> WIDE1-1>N789PH,WIDE2-1,qAR,W9DRR-10:`tR7+{A'/"S)}KD0CVN-1
>> RV-9A
>> > 
>> > The odd thing is that the "callsign" is
>> WIDE1-1 and N789PH (presumably
>> > the tail number) is the destination instead of the
>> "callsign". The
>> > owners callsign appears to be KD0CVN as indicated in
>> the status text.
>> > Don't know why he would include an SSID there!
>> Also according to the
>> > status text, it's an RV-9A.
>> > 
>> > I know the above doesn't show a path of WIDE1-1,
>> but looking at the
>> > tracker that IS using a "callsign" of
>> N789PH...
>> > 
>> > http://aprs.fi/?c=raw&call=N789PH&limit=1000
>> > 
>> > it is using a path of WIDE1-1,WIDE2-1. Surely if it
>> really is a plane
>> > wouldn't use a path of WIDE1-1,WIDE2-1 - hi!
>> > 
>> > Also, looking at
>> http://aprs.fi/?c=raw&call=WIDE1-1&limit=50
>> > it is possible that there is more than one station
>> with a misconfigured
>> > "callsign" of WIDE1-1.
>> > 
>> > 2009-03-14 14:36:43 UTC:
>> > WIDE1-1>N789PH,WIDE2-1,qAR,W9DRR-10
>> > :`tR7+{A'/"S)}KD0CVN-1 RV-9A [Invalid
>> characters in mic-e packet]
>> > 
>> > There's that "KD0CVN-1 RV-9A" again...
>> or possibly it's one and the same
>> > beacon. What a tangled web it is!
>> > 
>> > The callsign of WIDE1-1 must have been programmed in
>> accidentally. While 
>> > it is possible that a mangled MIC-E packet may be
>> involved for the 
>> > "emergency" beacon, perhaps it would be a
>> good recommendation for planes 
>> > to not use MIC-E to lessen the chance of a mangled
>> MIC-E packet making 
>> > it look like an emergency beacon. Just a thought.
>> > 
>> > 73 es cul - Keith VE7GDH
>> > --
>> > "I may be lost, but I know exactly where I
>> am!"
>> > 
>> > 
>> > _______________________________________________
>> > aprssig mailing list
>> > aprssig at tapr.org
>> > https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>> 
>>   _____  
>> 
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>> 
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>
>
>      
>
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