Wouldn't it be simpler to just drive the fence coil harder,
to make a stronger field? Or have more than one transmitter loop
and phase lock the drivers.

Surely you can capture the modulation with your sound
card and just LISTEN to it or view it with a wave file editor.
My guess would be that it is just a tone with PLL detector
  in the collar to prevent false triggers.

Robert


KY1K wrote:
> Hi All,
> 
> Yes, I have searched the archive:>:
> 
> Does anyone have any experience with the petsafe instant fence, 
> www.petsafe.net, model pif-300.
> 
> I bought one and was surprised to learn it was an audio amp feeding 
> several large air wound inductors with the output at 18.7 Khz. I used 
> spectrum lab to gather the spectral info and found the schematic of the 
> transmitter on the web. The output spectrum looks like the transmitter 
> is FM, which seems odd to me.
> 
> I've gathered quite a bit of technical info on the transmitter, but the 
> receiver (on the dogs collar) remains a mystery.
> 
> I need to expand the range, building a more sensitive receiver seems to 
> be practical (using the same transmitter).
> 
> Anyone have any experience with these sort of systems? Let me know if 
> you want further technical info, I'll gladly send you what I have.
> 
> Thanks,
> 
> Art
> 
> 
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist