[aprssig] Corrupted Data Pushed into APRS-IS

[Steve Noskowicz]

Added thought,

If it is a *different* Digi (not the iGate)that is mangling things, perhaps the *other* Digi's data would never get mangled ...?  NO ?

That is, if it has a receive problem.  If it has a transmit problem, then this wouldn't be valid.  

Around here, I frequently hear APRS "squwaks" that sound pretty funky that don't decode (on the D700 APRS screen).


73, Steve, K9DCI


--- On Mon, 8/10/09, Steve Noskowicz <noskosteve at yahoo.com> wrote:

> From: Steve Noskowicz <noskosteve at yahoo.com>
> Subject: Re: [aprssig] Corrupted Data Pushed into APRS-IS
> To: "TAPR APRS Mailing List" <aprssig at tapr.org>
> Date: Monday, August 10, 2009, 6:25 PM
> 
> 
> 
> 
> Doing a "stations near" on Findu at first it appeared that
> perhaps it is W4DKZ playing with calls:
> 
>  B4KDKZ-5  ** . . 34.04950 -84.19500
> 0.0   01:00:38:13  
>  W4DKZ-5  ** . . 34.05017 -84.17417 1.3  E
> 00:00:00:05  
>  E4DKZ-5  ** . . 34.06417 -84.21050 1.3  NW
> 01:00:31:49  
>  TW4DKZ-5  ** . . 34.06883 -84.20650 1.3  NW
> 01:00:28:09  
>  APDKZ-5  ** . . 34.07817 -84.19433 1.7  N
> 01:00:14:27  
>  W4DKZ-9  ** . . 34.07817 -84.19433 1.7  N
> 00:01:18:40 
> 
> 
> However, I (and in your examples) also see *YOUR* call sign
> being mangled:
> http://www.findu.com/cgi-bin/near.cgi?call=B4KDKZ-5
> 
> 
> As well as every other call in that area...which suggests
> the common element, the gate.  Do you see any of the
> calls being sent on RF also??
> 
> It is not clear what the "...DAD" is, but it appears the
> *real* Wx station is not mangled.  Also, the mangled
> calls have the same location as the real one.
> 
> I don't use UI-View, but wouldn't he see these on the
> computer display?  If he's using UI-View with a D700, I
> believe it is in TNC mode, not APRS, ? no?
> 
> 
> Things to check :
> the Gate's receiver frequency
>    receiver distortion
>    D700 <-> computer interface.
> 
> Doing an analysis of the bit patterns of the mangled calls
> *may* provide a hint, but most likely not.
> 
>   The D700 has a command "AI 1" that echos (CAT)
> commands, but I don't think it will provide any useful
> information in this case, but it can't hurt to try it --
> though it may mess up UI-View to have this data flowing to
> it..   "AI 0" turns it off.  It may not
> even accept this command in the TNC mode (my D700 CAT
> reference is on another computer not accessable easily right
> now)
> 
> There's some ideas.
> 
> 73, Steve, K9DCI
> 
> --- Brian McCarthy wrote:
> 
> > ...Hello All,
> > 
> > ... APRS packets with corrupted
> > callsigns are being forwarded into APRS-IS by a
> station near mine. I
> > had previously contacted the owner and asked he look
> at the situation.
> > He had not found a solution, and eventually turned off
> the igate he
> > was running. It took more a month for all the bad data
> to finally
> > decay out of the aprs.fi pages, but now the station is
> on and
> > forwarding bad data again.
> > 
> > Example bad callsigns include: B4KDKZ-5, R00O-9,
> DE3X9O,
> > TW4DKZ-5, HX9O, 5X9O-9.
> > 
> > If these callsigns were real, I would be having one
> whale of a good
> > time swapping HF DX'ing stories since many of them
> appear to be at my
> > location. Some of the calls are rare DX that I would
> enjoy working for
> > real. Anyhow, the bad data makes it hard to see what
> else is going on
> > in the near field.
> > 
> > In exchanging email with the owner of the station
> posting the bad
> > data, I gather that the radio and TNC are a TM-D700
> connected to a PC
> > with UI-View. I have never owned a D700 and cannot
> begin to suggest
> > where to look to find the problem.
> > 
> > Does the list at large have any suggestions?
> > 
> > Thank you,
> > Brian
> > NX9O
> > 
> > _______________________________________________
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> > aprssig at tapr.org
> > https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
> > 
> 
> 
>       
> 
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