Reading some information about the operation of TV detector vans (non UK readers may switch off at this point), I learn that they are not entirely passive listeners, but actually broadcast a signal which resonates with the innards of the telly (see link).

This should open the door to a household device to detect the approach of the dreaded vans, and issue an appropriate warning.
-- Mickey the Fish, Nov 24 2000

Short article on detector vans http://www.sciencen...iginal/t00033d.html
[Mickey the Fish, Nov 24 2000, last modified Oct 04 2004]

TV Licensing http://www.tv-l.co.uk/
Background for non-UK readers: In the UK, TV receiver owners are by law required to have a TV license to the tune of ~100 British Pound per year; fines for unlicensed operation run up to 1000 pounds. [jutta, Nov 24 2000]

TV Licensing get it wrong http://news.bbc.co....england/2835301.stm
License demand sent to ruined C11th Castle [oneoffdave, Oct 04 2004]

Another thing I wonder people will consider doing (not that I'd advocate it, mind) would be to very cheaply build oscillator circuits of the selected frequency and populate interesting, van-accessible places with them - in trees, under manhole covers, on roofs, under cars...
-- jutta, Nov 24 2000


Could this not kick off a TV detector arms race? Surely this will impel the TV detectives to create a TV detector detector detector, and the counter-detectives to build a TV detector detector detector detector, and soon the entire situation will collapse into gibberish and no one will get to detect anything.
-- Monkfish, Nov 24 2000


Watch TV within a Faraday Cage (with the antenna located outside of the cage, of course.) This is easily accomplished by placing your TV + associated furniture inside a Lion Cage (grounded), conveniently bought from your nearest Zoological Supplier.
-- dsm, Nov 25 2000


Sadly jutta they're one step ahead of you. The fiends are now armed with hand held detectors so that even those of us who have been able to hide safely in a block of flats for years are now subject to their depredations. This does leave them vulnerable to despicable tricks such as taping one of your oscillators to the back of a door that leads only to mid air. Cue Wil E Coyote style puff of dust as they hit the ground.
-- DrBob, Nov 26 2000


Actually, the history behind the UK TV detector van is rather interesting. Although the basic technology to do this sort of thing has been around for quite a while (and was in fact implemented by MI-5 for catching spies - see Wright's _Spycatcher_ for a very interesting account), urban legends about "TV detector vans" long predated the vans themselves. The rumors started because the authorities (who drove vans and carried some electronic equipment) would simply approach people who didn't have licenses but had obvious TV antennas, etc, to "remind" them of the licensing requirements. Much more often than not, the people so contacted would in fact have unlicensed sets, and would give themselves away under even gentle questioning; hence the legend of "detector vans". The authorties, naturally, did little to dispell the rumors, which did much to encourage compliance.

Only much later was this technology actually developed and deployed for its by-then-lengendary purpose.

A similar (and even more fanciful) rumor now circulating in the US concerns pirate software detector vans supposedly operated by the Business Software Alliance.
-- mab, Nov 27 2000


On the subject of TV detector related urban legends, and acquaintance of mine recently informed me of a new detector device, which could detect TVs even when they were switched off, and for a period of 7 days after last use! Sounds like complete bollocks to me.
-- Mickey the Fish, Nov 27 2000


Hmmm. Perhaps it's an optical device? I have a couple of optical devices capable of doing this.
-- Lemon, Nov 27 2000


Precisely. Most people seem to think the BBC is a GOOD THING. They would just rather someone else paid for it..
-- Lemon, Nov 27 2000


Who are these people, poking fun at our eminently sensible, fair and just TV licensing laws? Damn foreigners.. thats who. `waugsqueke' indeed. What sort of name is that then. Hmm?
-- Mickey the Fish, Nov 29 2000


Many of the key-cards folks use for access control work like this (that is to say they're passive). A diode attached to an antenna will broadcast a signal when in the presence of another signal, so I can see how it would be possible to detect an unpowered television. But then you'd detect televisions in junk yards, repair shops, etc. Maybe the solution is to grab some junked televisions and *bury* them around the neighborhood. Or you could create a device that 'lit up' (detector-wise) all televisions all the time (so no meaningful tracking could take place).
-- phoenix, Aug 10 2001


An low powered EMP device would be a fairly efficient TV detector remover, given that they are probably amplifying whatever signals they get quite a bit. An LCD monitor may not be visible to them. £100 a year isnt much if you work it out per week-certainly on a par with some of the satellite subscriptions. And they`ve certainly got nothing to shout about! Cheaper to keep a friend with cable supplied with blank tapes for the rare occasion they show something 1)good and 2)not likely to be broadcast on terrestial tv.
-- Pallex, Aug 10 2001


Currently it looks like the licensing authority have given up on detectors (far too expensive) and have just opted for sending threatening letters to everyone in the country in the hope that they will send money just to stop the barrage of unwanted brown envelopes.
-- DrBob, Nov 19 2001


They had these TV detector trucks in Denmark, too, when I lived there. I remember being quite incredulous when it was explained to me what it was they did.

So, is there no way to shield the set internally? What about if you have the antenna feed running to a TV card in a PC and watch on the PC monitor? Seems like that might get around it as the operational frequencies are quite different.
-- bristolz, Nov 19 2001


Sorry, [bristolz], the regulations refer to 'equipment capable of receiving a broadcast signal', which includes TVs, VCRs and ,yes, TV cards in PCs. Note that it says 'capable of receiving'. Even if you never use a TV, it must still be licensed.
-- angel, Nov 20 2001


Yes, [angel], that may be so but would the TV card escape detection? Also, if you do not own a TV, or receiving device, at all is this fee levied against you?
-- bristolz, Nov 20 2001


No, but if you previously had one then you'll probably get a threatening letter anyway.
-- DrBob, Nov 20 2001


(Hazy memories) The original detector vans could identify the station that you were watching because they worked by detecting the (accidentally radiated) output from the Intermediate Frequency Oscillator (the bit that converts the UHF to something lower). This stuff's all done in ICs now, and I've lost track of how they work, but I suspect that TV cards would be invisible to the detectors.
As the good doctor indicates, having ever owned a TV is grounds for receiving a reminder. At one time, TV retailers were obliged to inform the authorities every time they supplied a TV to a customer.
-- angel, Nov 21 2001


You have to pay money to watch TV?! Why, that's... Un-American!
-- snarfyguy, Dec 31 2001


Well, OK then, I'll put my hand up: I do not resent paying the licence fee. Not one jot. It's a bargain.

It buys me many, many hours of excellent TV programming across 2 terrestrial channels; local and national radio (I'd pay a few quid a week for Radio 4 alone); and the BBC websites, including news.bbc.co.uk which is, I think, the best news site around.

And all of it free of commercials. You can keep your American model: I prefer to watch my sitcoms without an ad break immediately after the opening titles and very 10 minutes thereafter. Ditto movies without regular ad breaks destroying the mood and tension...

As DrBob wrote, TV Licencing relies much more on databases and intimidation -- and an apparently unshakeble belief that *everyone* owns a TV -- than it does on detection.
-- JKew, Jan 01 2002


Re the Arms race for detector devices. Taking a leaf or two from Sir Douglas Adams book (literally), since technology will spread into the hands of resourceful yet tightfisted TV viewers, there will be a push to be on top of the detector detector hill. Soon it will become financially unfeasible to manufacture anything but detectors. This will eventually lead to A) the human race's evolution of a cranially mounted UHF-capable aerial and B) the collapse of all trade, service industries, agriculture and ultimately the collapse of humanity. It is unclear whether any of these consequences are negative or not, as we have only the current state of affairs to compare it to.

Can I pick up that piece of paper? Here I am, brain the size of a planet...
-- wossy, Feb 10 2003


From recent developments, I suspect that BBC themselves have started the whole licensing structure down the rocky road to oblivion. They have invested a substantial sum of the license money into creating a number of digital channels that most of their viewers can't receive and don't really want even if they could receive them. Change is just about to come galloping over the horizon, methinks.

As to what's going to happen when they turn off the analog signal in 2010 (I think). I predict chaos, anarchy in the streets, a revolutionary outbreak of people actually doing things in the evenings and a sudden dip in profits from the sale of armchairs.
-- DrBob, Feb 10 2003


What about recording on a video recorder in a metal box and then playing the tapes back on another vcr and a television with the tuners removed. This way you only record the programs you want to see. Tuners are very easily removed, it's the metal box that is connected to the aerial socket.
-- hector, Mar 08 2003


When you buy a TV from a retailer in the UK, they have to inform the authorities of who bought it and where they live. Then the TV people will write to you demanding money with menaces. Land Registry also inform them of property changing hands.
-- oneoffdave, Mar 10 2003



random, halfbakery