[Milsurplus] DFing receiver LOs and truck ignition radiation

[Ray Fantini]

Some years back I worked for a marketing research company and they tried to develop a system to automatically detect and log what channels people were watching. We did not waste time on trying to detect LO radiation due to most televisions built after the seventies radiate so little that it's not practical to receive a millo watt signal but we did use the output of the sweep stage of the TV that we were able to detect being most old analog sets developed a good six or eight watts of signal in their sweep stages at 15.75 Kc. You can compare the phase of the sweep signal to the phase of horizontal sync pulse of the broadcaster and determine if someone was watching the same channel. System was useless because in a urban environment there are so many sets you can't tell anything. This is why I am always so doubtful of the whole LO detecting story. The BBC still says they have TV detection vans that can now detect PC TV tuner cards but many are starting to question their ability to do this. There are no technical papers or equipment published or marketed for this function. Look at this web site for pictures of different detection vans thru the years:
http://www.oobject.com/category/sinister-bbc-spy-vehicles/
and maybe you can speculate what the antennas do. The art of deterrent is producing the fear in your opponents mind, real or imagined.
Ray Fantini KA3EKH

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of sdaitch at kuw.ibb.gov
Sent: Friday, December 04, 2009 3:54 AM
To: Ray Fantini; nerd at verizon.net
Cc: Milsurplus
Subject: Re: [Milsurplus] DFing receiver LOs and truck ignition radiation

My guess is the Brits were driving up and down 
streets, checking addresses which weren't reporting
and paying the fee for TV viewing.  House #134 
isn't paying the fee.  Let's drive over there and
with our monitoring system, see if there is any
LO radiation from that location.

Obviously, if the TV set was off, they'd never 
find it anyway.

I'd seriously doubt they were doing this from any
great distance.



----- Original Message -----
From: Peter Gottlieb <nerd at verizon.net>
Date: Friday, December 4, 2009 3:23 am
Subject: Re: [Milsurplus] DFing receiver LOs and truck ignition radiation

> Just coming into this, so I apologize in advance if this was 
> covered 
> already, but has anyone mentioned how the Brits used this 
> technique to 
> find "unauthorized" TV receivers?
> 
> 
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