[aprssig] APRS QSO frequency

Bob Bruninga bruninga at usna.edu
Sun Sep 30 10:17:45 CDT 2007

> As I understand from reading your webpage, the PL100 
> tone [for voice-alert on 144.39] is not digi'd?   
> So ANYTIME I hear the packet, that means someone 
> with PL100 is within simplex range? 

Yes, that is why it is a perfect "radar proximity detector" for any other APRS user in simplex range...

> I think this voice alert is GREAT - only problem, 
> the W4IAX-7 repeater doesn't respond to packets that 
> have PL100 tone attached. 

This is a good data point.  It would really be nice to see an oscilloscope on the audio going into that digipeater's TNC input to see what kind of distortion is on the signal.

First thing I woiuld try, is to sit in the vicinity of that digi and try your APRS packets with PL 100 set to 144.395 and 144.385.  If one works and the other doesnt, then this will tell us that the reason there is a problem, is because the digi's receiver is slightly off freqeuncy.  This will cause distortion on the signal, and then the PL tone will cause distortion products into the TNC...

Beyond that, not much you can do.  But the other things that can be wrong at that digi are:
1) digi receiver volume set to high to the TNC
2) audio passband skewed

but only the sysop can do anything  so.. good luck...


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