In reply to a post by nemeth782:

In reply to a post by Michael_Chare:

How is this done?

It isn't done, they lie to try to frighten people, detector vans are the same thing.

http://www.bbctvlicence.com/Detector%20vans.htm

Back in the old 4 / 5 channel TV's you could detect what channel / frequency you was watching, this was due to there wasn't really that much in the actual receiver.

Receivers in general require oscillators to generate the required offset frequencies so that they can tune to the required frequency / channel, these oscillators can be picked up if close enough to the TV and due to back then hardly any TV was screened which made it more easier to pick up when using directional antennas, modern TV's now days are all screened reducing the chances of picking up the oscillator in the TV in question.

So if "there was" such a thing as a detector van back then it probably would be useless now days.

But since nearly every TV now days is a Smart TV or has an external device turning it into a Smart TV, it would probably be easier for them to just get the required information from the ISP's when or if the require it.

Paul

Edited by PaulKirby (Sat 17-Dec-16 00:47:18)

Never did work, just had a few to scare people into buying a licence. Not one prosecution due to a so called detector van.
http://www.dailymail.co.uk/news/article-2445153/Are-...

In reply to a post by professor973:

Never did work, just had a few to scare people into buying a licence. Not one prosecution due to a so called detector van.
http://www.dailymail.co.uk/news/article-2445153/Are-...

I never said there was detector vans now or back then.

I was saying the engineering side of it was there, by saying that the old TV's back then radiated a lot noise out of the set including the oscillator used in them, this was due to them being made ion the cheap and not much of the cables was screened if any was.

I could even pick them up using a Spectrum Analyser with a preamp and directional antenna, it wasn't perfect but you could see the carrier about 20 feet away from it, so this part was correct, that's was I was getting at.

Even some TV's was worse and you was able to pick up the offset carrier and one of its harmonic frequencies.

*** update ***
And that ad always cracks me up, that Monty Python sketch in the ad had me in fits.
"What has the BBC actually given to us ?, Well ..."

Paul

Edited by PaulKirby (Sat 17-Dec-16 04:22:57)

Yes, technically it seems possibly feasible that someone could have used a device to detect the intermediate frequency leakage from a superheterodyne receiver, but firstly most TVs were double superhet making it harder, and there was nothing saying all TVs had to use the same IF, so it would have been a crapshoot.

Getting reliable triangulation data would also be very hard, you'd be detecting the antenna not the TV, so where you have flats with a shared aerial or semis with aerials on the shared chimeny stack, it would always have been useless.

And anyway, I was more focusing on the evidence that it isn't done

I did once see a blue Leyland daf van with a Logo on - I took a photo of it I am trying to find and if I do I will put it here.