I think they just presume that everyone has a TV and they seem to target anyone who does not pay for a TV licence.
An old work mate used to have regular visits from them. He invited one in for tea and went on to explain to the man that he didn't want the BBC's products and that they should stop harassing him for his choice of not wanting to pay for something he won't use.
What I'm interested in is how they know how many viewers watch a program?
Nah simple comparison of data. 1) List of addresses Vs 2) List of licensed addresses.
3) Visit all the unlicensed addresses.
Can someone explain how a detector van may work ? I can't see it. Smells like BS.
Society's to blame,
Or possibly Atari.
Saw some videos on YouTube last night of people filming the TV licence people when they arrived at their homes and I have to say that in all fairness the people coming to check were only doing their jobs, and if the people they came to visit had a TV and were using it to watch live broadcasts and were not paying for the licence I have no symoathy for you, I kept thinking pay your bills you skank.
Some of the people were just being plain rude and nasty to the bloke that came to do his job.
Someone did try to explain it to me once. Can't remember all the details now, but I do remember something about needing to two TV's; one set up to receive video only and another to receive audio. This was due to sepearating the signals to stop it being detected. How, I can't recall anymore.Originally Posted by Phage
While I agree with you that people should pay if they use it, Why don't the BBC just do what other pay channels do and encrypt their channels so people who don't want to pay for the BBC channels can just watch non BBC stations? I'm guessing because it would go down quicker than a lead weight off the Eiffel tower.
Considering how much revenue the BBC drags in under menace, I didn't notice many new things on the TV over Christmas apart from the Top Gear Christmas special.
Edit: Hmm, skip that, looked a bit iffy further down the page...
Anyway, it looked like the most obvious method was first related to CRT tubes and the EM radiation given off, and the other source was the oscillator loop.
It looks as though most "vans" these days just have a laptop with a database, and a lot of leaflets..
edit2: looks like the shift towards digital tv pretty much scuppers it..
Last edited by Stoo; 08-01-2012 at 01:12 PM.
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Well that just opens a total new can of worms. Not to mention not commercially viable either.
I can tell you how it used to work.
TV stations transmissions (and many others) work by overlaying the signal onto a carrier wave. The carrier, typically, increases the integrity of the signal over longer distances. So you've mixed two signals.
At the TV receiver, you need to reverse that process. You have a device in the receiver circuit called a mixer, and you feed in the signal from the aerial and a locally produced signal called an intermediate frequency (IF) signal. When you mix those two together, and filter the unwanted bits out of the result, the output is the desired TV signal.
And to pick the individual channel you want, you vary the exact frequency of that IF signal. So when you push the remote button, or the channel button on n old TV, or even turn the dial on an old FM radio, what you're doing is changing the frequency of the IF.
That's how a TV works. Or it was, in analogue days.
And that local oscillator that produces the IF? It transmits a very low-powered signal itself. With sensitive enough equipment, you can tell exactly what channel is being watched, because a given TV channel requires an IF of a specific frequency to be fed into the mixer. And as with any triangulation process, if you can get a direction of a source from two or more discrete points, you can identify a location. All you need is a highly directional antenna on your receiver, and a way to know exactly where it's pointed. I've done this as a game in the past, with a couple of handheld radio direction-finding sets, and a "rabbit" to chase.
And with a relatively high frequency IF signal, operating over a very small distance, the two RDF receivers do not need to be very far apart.
It is relatively easy to make fairly directional antennas. I've done it often enough, at home, with nothing more than copper tube or aluminium tube, a hacksaw and a power drill. As soon as you have a directional antenna, you have one that is very sensitive in some directions, and very much less so in others. In other words, you want good sensitivity, and selectivity. You want a high signal to noise ratio of the signals you're after, and good rejection of everything else.
The principle is sound, and at the sort of basic level I'm talking about, not hard to construct. Add sensitive receivers, and you have a relatively easy way to detect low-powered IF signals over very small distances. Do that with two receivers, and if the directivity of the antennas is good enough, you have a distance and direction for the transmitter (the IF loop). Add computer control, and you have an effective system.
These vans aren't (or weren't) BS. The techniques, in fact, are pretty much radio 101. The extent to which they were polished and refined was not. They exist. Or at least, existed. In the current digital world, I don't know, from personal experience. But the old analogue ones existed. G8ina said he's been in one. So have I, courtesy of an acquaintance in what used to the called, IIRC, the RadioCommunications Agency of the Home Office.
Saracen's description of radio transmissions is still accurate. We use digital coding schemes now but they're still mixed onto a carrier and the same is done on receive. However I don't know (well, can't remember) if anything is fed back up the antenna in a modern digital tuner.
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It used to be that there was a set-top box that monitored what was on the telly, then when you're in the room, you click 'your' button to tell the machine that you're in the room and watching that channel*. A girl I used to go to school with had this, but it was c20 years ago, so they might have changed it now. Can the likes of Sky+ & V+ report back what is being viewed? I hope not...
Edit: * The results would then be extrapolated I guess, with one of these boxes being in a selected cross-section of the telly-watching community.
Last edited by Smudger; 09-01-2012 at 01:32 PM. Reason: Addition
The channels are statistically-multiplexed together nowerdays so you wouldn't be able to see exactly what channel someone was 'tuned into' but other than that, as Steve said, not much has changed.
Im not sure if they use them anymore, not because the technology doesn't/couldn't exist but just because population density makes it difficult for them to be totally accurate (they couldn't seriously work well enough when it comes to a large block of highly populated flats) and general running costs are probably fairly high.
Honestly i don't know why anyone would bother trying to evade it, for the services the BBC provide for the UK I think its very reasonable. People who claim the BBC is a waste of money, i just wonder how they would feel it it disappeared and our television because more american-ized.
There was a scheme you signed up to and you then kept a diary of everything you watched, every time you changed hannels etc. Given a large enough sample, that gave representative viewing figures.
There were boxes that connected to the TV to automatically log channels and times, but iirc, they were more for psychology/sociology studies into the TV watching habits, rather than gathering programme info for advertisers.
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My broadband speed - 750 Meganibbles/minute
Not as many vans as you'd think it seems:
http://www.bbctvlicence.com/Detector%20vans.htm
Iv got a mate over at DB, might give him a bell see if he knows anything about them.
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