[aprssig] Corrupted Data Pushed into APRS-IS

[Steve Noskowicz]

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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