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Comment by Robadob | Hacker News Reader

The whole "detector van" thing is mostly a bogeyman to scare people.

The technology to remotely see what's showing on a CRT is Van Eck phreaking. Not sure over what distance it would be possible (and whether you could target a specific house accurately), also given the diversity in display technologies at current I can't see it being too effective.

http://en.wikipedia.org/wiki/Van_Eck_phreaking

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I think you could do a pretty good job just by watching the pattern of lights changing in a room, and comparing it to what's currently being broadcast. No need for Van Eck hackery.

AIUI (from distant days working at BT) the thing they were looking for was the EMR of the CRT flyback transformer. But it could only be detected if the television was towards the front of the house (not behind too many internal walls) and only on the ground floor.

That method has got no hope of detecting a modern LCD/OLED/Plasma display.

The majority of enforcement is database driven:-

Royal Mail database of addresses - addresses of current tv licenses = huge list of possible offenders

Now cross check database of possible offenders with databases of: * Sky or Virgin Media subscribers * people who have recently purchased or rented appropriate equipment (televisions, VCRs, PVRs, etc) * etc

Would it be possible to detect the transformer noise in the antenna cable? The cable often runs on the outside of buildings, especially older ones.

I thought that they were looking for the IF (intermediate frequency) being fed back up the antenna cable, but I have no source for that information other than "something my dad once said".

In reality, I'm sure it's like road tax, they check the database of addresses without one against a list of people who own a television. I believe all retailers are required to take a name and address when selling televisions.

Yes, van eck phreaking obviously works.

But is it actually used in the UK to detect people without a license?

Probably not, even though TVLA used to heavily advertise the use of detector vans.

TVLA have the largest civillian database in the UK so mostly they just send letters and inspectors to addresses without a licence.

The detector vans are most likely smoke and mirrors. Even when they had the technology, you don't need to use it in most cases, the van's presence is enough to scare people.

There's an interesting subculture of license refuseniks in the UK.

It does indeed seem to be true that the detector vans are pure PR, with no useful electronics. According to legend no data from a van has ever been used in a prosecution.

But it's a sad business. A lot of people who are caught and fined incriminate themselves unnecessarily.

They're almost always at the poor and not very educated end of the population, and will always accept a rubber-stamped prosecution because they literally have no idea they can often put up a defence in court.

Really, fining them four figures for what is really a trivial offence is unhelpfully nasty and persecutory.

The recent attempt to decriminalise non-payment of the license fee failed:-

http://www.bbc.co.uk/news/uk-politics-31151821

> They're almost always at the poor and not very educated end of the population > Really, fining them four figures for what is really a trivial offence is unhelpfully nasty and persecutory.

It's a great reflection of the sad state of the country.

https://www.youtube.com/watch?v=O-csYPQVaqA

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