BBC's Magic TV Detector Vans Kept Secret

from the state-secrets dept

As many of you probably know (especially if you live in the UK), you have to buy a license to have a TV (or even a TV tuner card for a computer). The license fees go to pay the BBC to operate. Apparently, the BBC has some secret "TV detector" vans that can sit outside your house and determine if you have an illegal TV (I only wish I were making this up). Someone filed a Freedom of Information request to find out how these supposed detector vans worked, but the request has been denied, and these magic detector vans shall remain a state secret. The BBC claimed that it could not reveal the details of the van "because if it did so it would damage the public's perception of the effectiveness of TV detector vans." I'm not sure, but I think that statement alone destroys the public's perception of the effectiveness of the TV detector vans. I'm guessing that the vans are totally empty but someone drives by your place at night and looks for the flickering glow.
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Filed Under: detector van, tv license, uk
Companies: bbc


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  1. icon
    Offbeatmammal (profile), 31 Oct 2008 @ 6:42pm

    Detector vans

    I thought they worked by some detection of induction frequencies or similar (at least that was the myth when I was growing up there!)

    they looked pretty scary ;)

    wonder if they're more sophisticated these days! ~Offbeatmammal

    link to this | view in thread ]

  2. identicon
    Anonymous Coward, 31 Oct 2008 @ 6:53pm

    "I saw one being pulled by a unicorn" Hahahaha

    link to this | view in thread ]

  3. identicon
    Anonymous Coward, 31 Oct 2008 @ 6:57pm

    holy cow thats awesome!

    "secret detector vans" - thats sweet

    link to this | view in thread ]

  4. identicon
    Darren Tomlyn, 31 Oct 2008 @ 6:58pm

    Re: Detector vans

    I know it's something like that - I'm sure my Dad explained it to me a while back when we were talking about tv cards in a PC and whether or not they'd bypass the detector vans - and he explained that they wouldn't and why - (he used to work on tv's and radios and stuff a while back) - I just wish I could remember what he said, sorry...

    link to this | view in thread ]

  5. identicon
    Anonymous Coward, 31 Oct 2008 @ 7:16pm

    Feh. It's always been a load of crap imo.

    If they had detector vans that could reveal whether or not you have an unlicensed TV (seriously how was that supposed to work in the first place), then they wouldn't have staff that knock on my door every 6 months or so to ask if I have a TV.

    The way I figured it, pretty much everyone in the UK has a TV set, so all they do is cross-check their license database with a census database and go round to each adress that has no license attatched to it.


    By the way, a minor point: You don't need a license if you have a TV. You need a license if you watch and/or actively receive TV signals as they're being broadcast. So if you have, say, a DVD player that can record (or a VHS player) without a TV, but you use it to record TV by hooking it up and just pressing "record" at the proper time, you need a license.

    But if you just use your TV to watch DVDs or play consoles, you don't need a license. All this stuff is on their site, they just don't like to publicise it (seriously, think of how much money they'd lose from students alone; yes you need a TV license if you live on campus, one for each person who has a TV).

    link to this | view in thread ]

  6. identicon
    Laurie, 31 Oct 2008 @ 8:53pm

    TV detector vans don't exist

    Wow, I can't believe this is being given any credence at all. There's no way to detect a TV from a distance, especially not with the advent of LCD and plasma TVs, and PC tuner cards. There's even less way to tell if the equipment is being used to receive a signal rather than, say, play a console game.

    The TV licence detection is based 100% on the assumption that everybody has a TV. The licensing authority simply sends letters to every house that doesn't already have a license.

    These vans do not exist, and have never existed.

    link to this | view in thread ]

  7. identicon
    Jeff Rife, 31 Oct 2008 @ 9:38pm

    Re: TV detector vans don't exist

    Yes, the vans exist, and, yes, they work. They work by detecting the radiation of the intermediate frequency (IF) that is used by all TV tuners.

    Basically, a TV tranmission is a 5-6MHz wide signal in the 50-800MHz range. The TV tuner takes the over-the-air frequency and shifts it down so that instead of being from 110-115MHz (for example), it is at 10-15MHz. This lower frequency is the IF, and like all receivers, it radiates at that frequency slightly (this is how receivers work...they vibrate in sync with the incoming frequency). The exact lower frequency varies slightly, but most designs are close to the same.

    The TV vans can detect this signal.

    If you think it's a load of rubbish, remember that a slightly better antenna in the van can be used to decode your keystrokes from the signals emitted by your keyboard, or read your PC monitor because of the signals emitted as it draws the display.

    link to this | view in thread ]

  8. identicon
    Zaphod, 31 Oct 2008 @ 10:26pm

    TEMPEST and other nasty ways to sniff intelligence.

    I am afraid that there is a better reason that the gov. in the UK can't release specs, is because they have the equipment under contract from the USA.

    See http://en.wikipedia.org/wiki/TEMPEST about E.M. Elint sniffing.

    And there is another much more simpler way to do a detection, and yes, it's based on seeing the flicker, but then they correlate it with the known luminosity levels of the live BBC transmissions. Very easy to see if 2 needles are swinging in concert. Just mount one CdS cell in a de-focused telescope eyepiece, and the other in a light box around a monitor. Run a battery through each, and run the ourput to a meter. Instant snoop, and worse, it can be done from a hilltop miles away.

    There is, however a bigger problem in this, is that they can profile your viewing habits! Know an enemy by what he reads (library records), and watches.

    Do brits ever set up the home theatre in the basement/cellar? Perhaps it's time!

    link to this | view in thread ]

  9. identicon
    Lee, 31 Oct 2008 @ 10:37pm

    Re: Re: TV detector vans don't exist

    Thank you for such a concise, technically accurate answer. Just like they have "radar-detector" detectors in the USA.

    link to this | view in thread ]

  10. identicon
    Mark, 1 Nov 2008 @ 12:17am

    Radar Detector Detectors pick up the radiated IF signal radiated by the detector. Some detectors are more difficult to pick up due to pains taken by makers to limit this radiated energy, but most are still vulnerable to a lesser or greater extent. Dedicated LADAR detectors radiate nothing, but then they just tell you when you got nailed anyway.

    I don't know which is worse. Paying for a license so you can watch crummy TV, or watching commercials so you can watch crummy TV...

    link to this | view in thread ]

  11. identicon
    Anonymous Coward, 1 Nov 2008 @ 12:18am

    Re: Re: Re: TV detector vans don't exist

    Uh, wow.... Can't tell you how wrong this person is. As for the keyboard detectors they only work when basically there is no other noise at all from anything (like say, a power supply or a wireless network etc)

    This falls under the same problem -- its probably obscured by gsm or your remote or a microwave or a million other things that flood the electromagnetic spectrum

    link to this | view in thread ]

  12. identicon
    Anonymous Coward, 1 Nov 2008 @ 12:21am

    Re: Re: TV detector vans don't exist

    http://www.autoblog.com/2008/06/09/a-visual-history-of-the-bbcs-tv-detector-vans/

    "
    To subsidize the BBC's programming, UK residents are compelled to pay a TV licensing fee (this is what we also call a "tax") if they choose to watch television programs in their homes. To encourage compliance, the Beeb invented the myth of the "Television Detector" van, which supposedly contained powerful antennae that were capable of zeroing in on any house that was watching television without a license."

    link to this | view in thread ]

  13. identicon
    Anonymous Coward, 1 Nov 2008 @ 12:31am

    The way I understood it when I was in London for a year in school was that they sent people who had the right to come search your apartment and fined you for an unlicensed TV whether you used to receive signals or not.
    I paid for the license even though I just had an Xbox hooked up to the set most of the time.

    link to this | view in thread ]

  14. identicon
    Molly, 1 Nov 2008 @ 12:41am

    The Young Ones

    "Oh no lads, he's asked me if we have a telly. I think I'm going to have to lie! "

    Just remember, if they nick ya, eat the telly.

    link to this | view in thread ]

  15. identicon
    Richard, 1 Nov 2008 @ 12:49am

    Re: Re: TV detector vans don't exist

    You are such a dumbass. Do you wear a tinfoil hat? Those of you who believe this bunk, deserve to be paranoid.

    link to this | view in thread ]

  16. identicon
    Daniel Kaiser, 1 Nov 2008 @ 12:55am

    Just wrap your house in copper mesh, no RF no problem, of course it will keep your cell phone from working.

    link to this | view in thread ]

  17. icon
    PaulT (profile), 1 Nov 2008 @ 1:49am

    Re: Re: TV detector vans don't exist

    ...and how does that detect whether the TV is licenced? Are there really no other signals that can possibly occur in those ranges? Either way, they depend on you being unlucky enough to be watching TV on a unlicenced device at the exact moment a van comes driving down your street.

    Whether or not they really "work", the detector vans were just a ruse to get people to pay the TV licence - they're more likely to pay if they think they'll get caught.

    The reason most people think they're a load of c**p is that as increasing numbers of people don't watch TV, they've had to deal with the licencing authority to stop getting demands sent to them. I know 2 people who either don't TVs in the UK. Every year, they have to fight the TV licence people to convince them they don't own a box. Demands are sent out to them, even though there's no way they could have detected a signal with there not being a TV or other receiving equipment in the house.

    Face it, whether the vans really work or not, it's cheap and easier for them to assume that every house has a TV then deal with complaints from those who don't, than it is to actually have an army of the vans checking every street in Britain.

    link to this | view in thread ]

  18. identicon
    Anonymous Coward, 1 Nov 2008 @ 2:25am

    For the doubters I recommend reading Spycatcher: The Candid Autobiography of a Senior Intelligence Officer by Peter Wright, the former assistant director of MI5.

    In the book he describes how they made 'radio detector' vans to locate Soviet operatives in London. The technology has been around for a while

    link to this | view in thread ]

  19. identicon
    zcat, 1 Nov 2008 @ 2:25am

    flickering glow...

    I'd agree with the 'flickering glow' theory. When there's only a few channels it's not too hard to surf through them all and when you're on the same channel you can tell in a matter of seconds because there are sharp changes in colour or brightness. They'll either be completely different, or perfectly matching.

    How do they know it's an 'unlicensed' TV? Well, first they make a list of all the address that don't have a TV licence.. then they go around those addresses at random times in the evening and see if they can 'detect' the presence of a TV tuned to a broadcast frequency.

    The IF thing is (IMHO) very likely bullshit spread to obfuscate the truth.. most TVs radiate tiny amounts of IF and it's quite tricky to pick it out and DF it. MUCH easier to just look for the tell-tale glow on the wall.

    link to this | view in thread ]

  20. identicon
    Tony Rothwell, 1 Nov 2008 @ 2:45am

    BBC

    SKY TV - £480 a year
    BBC TV - £130 and no adverts.

    Pay the licence fee. It's superb value.

    Now stop worrying about detector vans.

    link to this | view in thread ]

  21. identicon
    Anonymous Coward, 1 Nov 2008 @ 3:50am

    They don't exist

    They are a myth used to scare people in the past. Now they send letters to any house that doesn't have a license, but rarely follow up since they know it's a guess. As a side note, if they knock on your door they have no right to enter your house.

    link to this | view in thread ]

  22. identicon
    Anonymous Coward, 1 Nov 2008 @ 3:57am

    #5 is wrong, saddly

    Actually, the law in the UK is that *any* piece of equipment capable of translating a TV broadcast signal into a visual signal requires a TV licence.

    Hence schools have to actually cover their oscilloscopes with a TV licence if they are in a block of buildings away from the TVs that they already licence.

    Dumb, isn't it?

    link to this | view in thread ]

  23. identicon
    Douglas Gresham, 1 Nov 2008 @ 4:12am

    Re: Re: Re: Re: TV detector vans don't exist

    They don't need proof-positive that you have a TV on, they just need a reason to come in and check, however flimsy that may be. Then, of course, they run into situations like a ton of people living in a managed building (such as mine) where everyone has to have their own TV licence - which they respond to simply by continually sending out notices to any rooms without a licence.

    The detector vans are a formality, nothing more. I suspect the beeb don't want us to think that way because they couldn't handle it if significant numbers of people stopped paying they wouldn't copy, which could well be what would happen if the detector vans were showed to be flawed.

    link to this | view in thread ]

  24. identicon
    SteveD, 1 Nov 2008 @ 4:18am

    Urban Legend

    Its probably a myth they used to scare people into paying before databases. Why would they need to use detectors these days?

    You're required to pass on your address when you buy a TV, so they know straight away if you don't buy a licence for it. On top of that they always bug you to re-licence...one year back in Uni the flats licence was in my name. The next year a new chap moved in with a bigger TV, so I left mine behind and he took out the new licence in his name.

    Que BBC sending me letters telling me to get a new licence. I figured it was a mistake and ignored it, but then they sent another letter stating that because I'd ignored them they'd passed my details to a collection agency...

    link to this | view in thread ]

  25. identicon
    Merijn, 1 Nov 2008 @ 4:39am

    It's all in the database...

    The current scare-ruse the bbc sends out between programs is a flight over a computer motherboard, stating "your house, your tv, it's all in the database..."

    In the Netherlands the tv-license fee was dropped in 1-1-2000 because you can safely assume everybody has a tv, and the normal taxes were raised by a fraction to compensate.

    link to this | view in thread ]

  26. identicon
    Michael Foord, 1 Nov 2008 @ 5:04am

    Detector Vans and Licenses

    Yes detector vans are real, they can detect the RF signals used to decode the TV signals radiated back through the arial. This doesn't work if you use cable (no arial).

    They can tell if it is unlicensed because they know who has paid the license fee...

    Some people have odd ideas about the law on licenses (a license for an oscilloscope!!?!?!?). You only need a license if you watch (receive) broadcast television (even if you only watch ITV or Sky you need to pay the license).

    If you don't watch TV then you don't have to pay the license. If you have a TV capable of receiving broadcast signals and it is connected to an arial then you will have a hard time proving you don't watch TV...

    License inspectors don't have the authority to come into your home unless they have a court order.

    Oh - and the spycatcher bloke was bullshitting when he claimed to have invented the technology. It's pretty basic electronics.

    link to this | view in thread ]

  27. icon
    Eclecticdave (profile), 1 Nov 2008 @ 5:05am

    Freedom on Information

    Regardless of whether these vans exist or not, does the Beeb have the authority to not release this info?

    I thought a request under the Freedom of Information Act could only be blocked if it's a state secret. Do the Beeb's attempts at licence policing fall under National Security these days?

    (Maybe they're worried there'll be riots if the word gets out detector vans don't exist ;-)

    Anyway, I'm not an expert in radio, but I was under the impression that a directional antenna designed to pick up these tiny signals would have to be quite big, and outside the metal chassis of the vehicle. So unless the Beeb is now using Fibre-glass based Robin Reliants, it's had to see how these detectors could be "hidden".

    link to this | view in thread ]

  28. identicon
    Michael Foord, 1 Nov 2008 @ 5:06am

    Re: Re: Re: Re: TV detector vans don't exist

    The signal is radiated back out by the arial. Not hard to detect. Harder if you receive via satellite or cable of course.

    link to this | view in thread ]

  29. identicon
    Jake, 1 Nov 2008 @ 5:10am

    Re: BBC

    Hear hear. They could stand not to be quite as threatening about the way they go about checking for compliance, but if someone here has a suggestion for some means of enforcing this that doesn't intrude at least somewhat on people's privacy, let's hear it.

    link to this | view in thread ]

  30. identicon
    Michael Foord, 1 Nov 2008 @ 5:12am

    Re: Re: Re: TV detector vans don't exist

    They send threatening and demanding letters to any address without a license.

    The detector vans are completely unrelated to this. Detector vans are used to gather evidence before getting a court order.

    You can write to the BBC and withdraw their right to even come and knock on your door. If you do this they will leave you alone for two years.

    I don't have a license (we have a TV to watch DVDs but no arial). They regularly send me letters, but no-one has ever turned up at the house.

    link to this | view in thread ]

  31. icon
    Eclecticdave (profile), 1 Nov 2008 @ 5:13am

    Re: Freedom on Information

    I know, I know - RTFA! My bad.

    Apparently the Information Commissioner ruled that it was "in the interest of legitimate licence payers" to not receive information that might lead them to question whether they really need to pay the fee!

    Got to love the logic ;-)

    link to this | view in thread ]

  32. identicon
    a f man, 1 Nov 2008 @ 5:36am

    they are empty vans

    they cant detect jack s**t , they will come to your door if you are not registered as having a licence and ask you if you are watching TV , depending on your responce they will/can get a court order . i was "cought" by one of these vans and the bbc man could clearly see my tv in the room through the patio doors . His responce was to accuse me of watching a tv without a licence , as if !!! . i simply denied it and locked the door and walked off down the street , muppet with clipboard in tow asking stupid questions over and over again :-) . needless to say i only got a thretning letter through the post .
    the moral of this story is NEVER , EVER , EVER!!!! admit you have or were watching a tv on premices without a licence.

    link to this | view in thread ]

  33. identicon
    Anonymous Coward, 1 Nov 2008 @ 5:41am

    The Real Scoop on the Vans

    What happened is a bunch of EE nerds went to BBC management and said, "You know, we can make a van that will detect if anyone is watching TV without paying the tax." Management, not knowing any better, gave them a bunch of money to develop it. The nerds filled the van with a bunch of impressive looking equipment, and now they drive around all day watching porn videos on it. If management ever checks in on them they just say, "It's what these pervs watch. We have to keep an eye on them because any minute they're going to turn on the Beeb. Just one of the many indignities we have to endure in service of the public."

    There, their little secret is out.

    link to this | view in thread ]

  34. identicon
    Andy, 1 Nov 2008 @ 5:47am

    Not the BBC, the TVLA

    A licence is required in the UK to receive TV of any kind, whether it is the BBC, another terrestrial channel, cable or satellite. Even if you never watch BBC TV you need a licence. This is not by any means unique to the UK. It applies in Sweden (where I have lived), Finland (where I live now) and no doubt in many other countries which have a state-controlled, commercial-free network.

    link to this | view in thread ]

  35. identicon
    Herb, 1 Nov 2008 @ 5:48am

    TV Detector Van

    I grew up in Germany (back then in the WEST) and we had the same TV tax and those rumored detector vans. That was back in the 60's and 70's, so maybe there is some truth to that?

    link to this | view in thread ]

  36. identicon
    Mark, 1 Nov 2008 @ 6:06am

    Licenses?

    I am so glad I live in the US. Pay to watch commercials? Are f'ing kidding me?

    link to this | view in thread ]

  37. identicon
    Anonymous Coward, 1 Nov 2008 @ 6:31am

    I lived in the UK for about 18 months in a 4th floor apartment but I never had a TV. I got a demand to pay a TV license when I first moved in and again every few months after that. Total BS. They didn't use a 'detector van' because there was nothing to detect. They simply sent a demand notice to address that didn't have a license on file.

    link to this | view in thread ]

  38. identicon
    dan, 1 Nov 2008 @ 6:37am

    Omg. So people in the UK have to pay for TV too?! Whats the world coming too!

    link to this | view in thread ]

  39. identicon
    john, 1 Nov 2008 @ 6:55am

    Not so secret secret vans

    I lived in northern England 91-93. The vans weren't very secret then. They could detect the use of a 'telly' inside a residence and, by matching up the location with issued licenses, could determine if it was 'legal' or not.

    The effectiveness seemed to be greatly limited by distance. I know a very small U.S. military base refused entry to the vans and they could therefore not check base residents' TV's eventhough roads outside the base ran less than a mile from the housing.

    The licenses fund the BBC which is commercial free.

    link to this | view in thread ]

  40. identicon
    Ajax 4Hire, 1 Nov 2008 @ 7:05am

    Re: Re: TV detector vans don't exist

    ha-ha-ha-haaaa-ha, You don't know what you are talking about.

    You are just making up James Bond stuff.

    TV and all electronics have a requirement to NOT radiate.

    Not every TV uses the same IF, there are many silicon tuners that do a direct conversion (no IF down convert). There would be no way to detect something that is not there, doofus.

    The IF can vary from 10MHz-50MHz, depending upon the TV Tuner manufacture and the tuned channel. If I wanted to annoy the TVvans, I would simply put a CB-radio broadcasting at 27MHz, maximum power; this would swamp out any TV IF for mile, doofus.

    You are just making up stuff you heard and read.
    Get a real degree in Engineering and you would know better, doofus.

    link to this | view in thread ]

  41. identicon
    Rick, 1 Nov 2008 @ 7:41am

    They use them in the USA too.

    About 12 years ago I hooked my television up to the cable outlet in a new home. The cable was already turned on, so I used it - hey, it was free.
    Anyway, about 3 months later a guy from Charter came to the door asking me to pay for that months 'cable bill.' They had driven by and 'detected' that I was using cable in the house.
    I declined to pay him, so he went around the back of the house with a shovel to disconnect me at the junction. (The cable lines were underground in this neighborhood.)

    link to this | view in thread ]

  42. identicon
    Anonymous Coward, 1 Nov 2008 @ 7:47am

    "#5 is wrong, saddly

    Actually, the law in the UK is that *any* piece of equipment capable of translating a TV broadcast signal into a visual signal requires a TV licence.

    Hence schools have to actually cover their oscilloscopes with a TV licence if they are in a block of buildings away from the TVs that they already licence.

    Dumb, isn't it?"

    As I said in my post (I'm #5... I AM NOT A NUMBER!), the beeb will repeatedly lie, *especially* the people who come around houses, and then again *especially* the people who come to university residences (campuses etc...).

    Last year, for example, they came around my campus. Amongst the things they lied about:

    1) They claimed they had the right to enter private rooms and check for TVs with arials. False. The only authority in the UK legally allowed to enter private property without permission (not including SAS style sieges...) are the police, with a warrant (yes that includes balifs).

    2) You need a license if you use youtube, or 4 on demand, or any other such website. False. The TV license is for actively receiving TV signals as they're broadcast. You do *not* need a license to watch anything pre-recorded, whether it's a tape, DVD, video game or internet video.

    3) You need a TV license if you have a TV, whether or not you use it to watch TV. False. You only need a license if you're actively watching TV.

    4) (and this was the worst one), they managed to scare a friend of mine into thinking they had the right to search her laptop for any "potential software used to avoid paying for a license". What utter and complete bullshit.


    The License enforcers are either liars or just extremely incompetant. Either way, they are total cunts, ready to scare you into paying them, whether you need to or not.


    If anyone disagrees (or simply doesn't know) with my claim that you don't need a license to have a TV and just watch DVDs and/or play games, this is right from their own website:

    "What if I only use a TV to watch videos/DVDs/as a monitor for my games console? Do I still need a licence?

    You do not need a TV Licence if you only use your TV to watch videos and DVDs or as a monitor for your games console.

    However, please notify us in writing that this is the case. One of our Enforcement Officers may visit you to confirm that you do not need a licence."

    http://tvlicensing.metafaq.com/templates/tvlicensing/main/answerPage?_mftvst:answerRef= %24http%3a%2f%2fapi.transversal.com%2fmfapi%2fobjectref%2fEntryStore%2fEntry%2fhttp%3a%2f%2fwww.meta faq.com%2fmfapi%2fMetafaq%2fClients%2ftvlicensing%2fModules%2flicensingInfo%2fTopics%2fgeneral%3a134 832%3a4&_mftvst:moduleID=%24licensingInfo&_mftvst:topicID=%24&id=VD7H3U82KVKRVE09L0COQLP 6C0

    That link is kinda long. Alternately, you can just go to http://www.tvlicensing.co.uk/index.jsp and type "DVDs" into the search bar in the middle of the page.



    As a side note, I happen to somewhat agree with the TV license. In the past at least, it's let the BBC fund relative unknowns into making great shows since they don't have to worry as much about pandering to the masses since they technically don't need huge viewer ratings to get good money from advertisers. I just take extreme issue with the way the license is enforced.

    link to this | view in thread ]

  43. identicon
    Anonymous Coward, 1 Nov 2008 @ 8:03am

    it is possible to inject test signals (known patterns) into the carrier that will cause intentional effects of overmodulation (subtle interference) that, theoretically, could be "listened" for in such a way to detect if you are currently watching a channel (i.e., tv set is emitting the known interference pattern for a given input)

    Zaphod is EXACTLY right with TEMPEST. This is a well-known issue. With the right sophisticated gear, you can reproduce the screen on someone's computer monitor across the street.

    And to ajax_4hire - all electronics radiate some sort of energy pattern (interference) that can be detected (unless they are heavily shielded - which is usually very cost ineffective, except for military and certain industrial applications). The laws set LIMITS on the amount interference is allowed from the radiation.

    link to this | view in thread ]

  44. identicon
    James Gresham, 1 Nov 2008 @ 8:08am

    From tvlicensing .co .uk

    "We will only use detection equipment to identify evaders when other, more cost effective, routes have been exhausted. TV Licensing aims to maximise licence fee revenue by collecting the fee in the most cost efficient way."

    This implies that it isn't so much that the detection is utterly useless, but that it is simply much cheaper to mass mail. This makes a lot of sense if the vans have a very limited range - can you imagine how many vans and how many man hours you would need to check every home (including seperate flats etc in a single building) in the UK without a TV licence?

    The BBC seems to want to maintain the impression that the moment you stop paying your licence, a flashing red light will go off at headquarters and Thunderbird 1 will land in your back garden bristling with sensors and technology. That too is understandable, as it will vastly increase the take up rate of licences and the response to warning letters, though I don't agree with the decision to withhold the specifications of the detector vans.

    Personally I approve of the TV licence, as in addition to high quality commercial free programming, having a news organization which is independent of commercial sponsers, investors or political parties can only be a good thing. In the united states news programs go after market share - worrying for a country where partisanship is integral to the political process.

    link to this | view in thread ]

  45. identicon
    Phil Walliams, 1 Nov 2008 @ 8:25am

    It's done at the point you buy the TV

    I actually work for the BBC and it is even simpler than you think. Every time you buy a tv, the retailer by law has to declare your details to the BBC. We then register you have a TV and check for a license... Simple

    link to this | view in thread ]

  46. identicon
    ehrichweiss, 1 Nov 2008 @ 8:26am

    Re: Re: Re: TV detector vans don't exist

    The requirement isn't to NOT radiate but to only radiate up to a certain strength because there is no way to put the entire telly in a Faraday Cage, the only way to really prevent any radiation from leaking. The requirement by the FCC here in America is that the device cannot cause interference, not that it can't radiate RF.

    Most TVs use IF(and the same frequency at that) because most manufacturers use the same chips and it's easier to get a better picture with IF[direct conversion is better but requires more expensive parts and engineering].

    And there IS a way to detect even with direct conversion and LCD, or are you not aware of the new LCD version of TEMPEST?

    If YOU were a real engineer you would know all of that and you'd know that if you used your CB at that strength they would triangulate and nab you for something entirely different.

    link to this | view in thread ]

  47. identicon
    Anonymous Coward, 1 Nov 2008 @ 8:32am

    Re: Re: TV detector vans don't exist

    So since there is a tuner in my DVR and in by VCR, does this mean I need a license for each as well?

    link to this | view in thread ]

  48. identicon
    Mike, 1 Nov 2008 @ 8:37am

    TV Detector

    I seem remember being told this back in 1996 while studying in the UK from the States. It was alleged back then that vans would circle around neighborhoods looking to find TV and then check they were licensed. We had a German geezer living in our flats that hung aluminum foil around his windows.

    link to this | view in thread ]

  49. icon
    vidiot (profile), 1 Nov 2008 @ 8:51am

    Old news

    True or not, this story has been around forever. Anyone remember Monty Python's parody, "The Cat Detector Van", which could "pinpoint a purr at 400 yards"? Yes, that's what they were spoofing... and that was 1969.

    link to this | view in thread ]

  50. identicon
    Crazy I guess, 1 Nov 2008 @ 8:54am

    WOW

    I can't believe that no one across the pond even questions why everyone that gets over the air tv of any kind should have to subsidize the bbc. Wow.

    link to this | view in thread ]

  51. identicon
    Phil Walliams, 1 Nov 2008 @ 9:25am

    It's done at the point you buy the TV

    I actually work for the BBC and it is even simpler than you think. Every time you buy a tv, the retailer by law has to declare your details to the BBC. We then register you have a TV and check for a license... Simple

    link to this | view in thread ]

  52. identicon
    Anonymous Coward, 1 Nov 2008 @ 9:29am

    BBC commercial free?

    They spend more time between programmes advertising their forthcoming low budget efforts than any ad break on the commercial stations. And at least five minutes of each major news programme is dedicated to 'news' on the latest questionable documentry.

    They also decided to stop using the post office for payments. Making it impossible to get a licence without going through them directly, and diffcult to setup payment without credit card or direct debit (ok until you cancel and they decide they still want your money)

    link to this | view in thread ]

  53. identicon
    Anonymous Coward, 1 Nov 2008 @ 9:37am

    Re: Re: TV detector vans don't exist

    http://www.autoblog.com/2008/06/09/a-visual-history-of-the-bbcs-tv-detector-vans/

    "
    To subsidize the BBC's programming, UK residents are compelled to pay a TV licensing fee (this is what we also call a "tax") if they choose to watch television programs in their homes. To encourage compliance, the Beeb invented the myth of the "Television Detector" van, which supposedly contained powerful antennae that were capable of zeroing in on any house that was watching television without a license."

    link to this | view in thread ]

  54. identicon
    James Gresham, 1 Nov 2008 @ 9:45am

    Re:

    BBC doesn't interrupt programmes for advertising - which means you get a break at the beginning and end of an hour long program, rather than beginning, end and three in the middle. Also, I'd dispute the idea that beeb breaks are as long as commercial ad breaks.

    What exactly do you mean by questionable documentary?

    Also, there is no shortage of ways to pay - most depend on cards because, well, thats the way the vast majority of subscriptions work nowadays. You can still pay without a card though (a cheque by post, for example).

    link to this | view in thread ]

  55. identicon
    Ugly Wierdo, 1 Nov 2008 @ 9:57am

    Re: They use them in the USA too.

    Uhhh...
    They can't do that dude.
    NOBODY can enter your property except police, and then they require at the very least, probable cause.
    Cable companies in the U.S. do not use the vans because that would violate privacy rights and they could be hit with a massive lawsuit.
    Either you were had, or you were telling a stupid little story.

    link to this | view in thread ]

  56. identicon
    Anonymous Coward, 1 Nov 2008 @ 10:15am

    Re: TV Detector Van

    This story is funny on so many levels.

    link to this | view in thread ]

  57. identicon
    Chris, 1 Nov 2008 @ 10:24am

    Just pay for the license if you watch the programming, it can't possibly be that much.

    link to this | view in thread ]

  58. icon
    Peet McKimmie (profile), 1 Nov 2008 @ 11:24am

    The inside scoop

    A friend of mine worked for the GPO ("General Post Office") who used to run this fleet of vans. Apparently, one of her least favourite jobs was sitting inside the almost-empty van (the equipment had been taken out some ten years earlier) on a plastic chair and cranking a little handle to make the antenna on the roof rotate as the driver drove slowly up and down a different few streets every night. The next day the Post Office that served those streets would get a huge boost in sales of TV licenses.

    link to this | view in thread ]

  59. identicon
    Anonymous Coward, 1 Nov 2008 @ 11:36am

    wow, the uk is such an oppressive POS country.

    link to this | view in thread ]

  60. identicon
    J. Adam Moore, 1 Nov 2008 @ 11:40am

    Van Eck Phreaking

    It's called Van Eck Phreaking, and you can use something called a Faraday Cage to ground the transmissions. Simple stuff, really. Does anyone read past what the teacher tells them? School is FAIL.

    link to this | view in thread ]

  61. icon
    Peet McKimmie (profile), 1 Nov 2008 @ 11:43am

    Re: Re: TV detector vans don't exist

    It's a nice theory, Jeff, but not the one I was told when I was in the process of failing my BSc in Electronic and Electrical Engineering...

    Basically, they were far more simple setups. They "listened out" for the vertical frequency of the scan coils in a tube TV, which you could pretty much pick up with a coil of wire and a diode. This was fed into an oscilloscope and compared to off-the-air signals to determine which channel was being watched. (There was a phase variance between the channels) The two antennae on the van were used to "triangulate" over a short distance to tell whether the TV was in the front or back of the house - it was assumed, when the vans were designed, that all TV sets would be on the ground floor.

    All of that worked, back in the days of VHF TV. When UHF came out they still told you where the TV was, but the equipment in the van could no longer tune a reference signal and so they lost the ability to knock on your door and tell you what you had been watching. But this didn't seem to reduce the effectiveness of the vans, so they let that slide...

    Nowadays, the best they can tell you is that someone is running a "tube" screen in the house, and whether it's refreshing at mains frequency. With the rise in popularity of flat screens they are functionally useless, but the psychological effect of driving them slowly up and down a street in the evening seems to be enough to justify the expense of keeping them on the road.

    link to this | view in thread ]

  62. identicon
    Anonymous Coward, 1 Nov 2008 @ 11:51am

    Re: BBC

    Don't own a telly. People search my house regularly for one. Sodden annoying!

    link to this | view in thread ]

  63. icon
    Peet McKimmie (profile), 1 Nov 2008 @ 11:51am

    Re:

    Radar Detector Detectors pick up the radiated IF signal radiated by the detector. Some detectors are more difficult to pick up due to pains taken by makers to limit this radiated energy


    Er... duh! Radar Detectors work by blasting you with energy so they can see the reflection - Radar Detector Detectors detect this energy and set off an alarm. There's no "IF", no faffing about with "shielding"...

    link to this | view in thread ]

  64. icon
    Peet McKimmie (profile), 1 Nov 2008 @ 11:56am

    Re: flickering glow...

    They'll either be completely different, or perfectly matching.


    Except, if you're watching on a Digital service, your picture will be delayed by between 1 and 4 seconds depending on the electronics at your end. (Longer if it's me watching ITV as I always pause the programme for ten minutes at the start so I can skip through the timeshifted ads... ;-D)

    link to this | view in thread ]

  65. identicon
    Anonymous Coward, 1 Nov 2008 @ 11:58am

    Oh the BBC and their evil money-grabbing TVL company make me laugh.

    Approximately every month, I get a knuckle-dragging skinheaded moron knocking on my door demanding to enter my house to see if I have a TV, and every time, I ask them if they still have those detector vans, they of course say yes. "Then use one, and stop wasting my damn time, thank you". You'd think they'd stop coming, but no.

    This has been going on for 2 years, and they just can't understand that I don't want their damn TV license. Their basic assumption is that if you don't pay them £140 a year (not exactly, but that's roughly the amount for a colour television), then you ARE a criminal, you just haven't been caught yet.

    I'm considering setting up the Washing Machine Licensing Company, and knocking on the doors of anyone who works for the BBC so that I can assess whether they need to pay me an annual fee.

    link to this | view in thread ]

  66. identicon
    Davkaus, 1 Nov 2008 @ 12:04pm

    "Pay the licence fee. It's superb value."

    Is it really? The thing is, I want to pay to watch SKY, I don't care about the adverts, I want to watch the shows that they have, not the dross that's on our so-called Independent channel. The fee was fine, wonderful even, when the only channels were BBC (I believe it originated before TV, for radio, and the BBC had the only channels), but in this day, it should be subscription based. They shouldn't get money from everyone who wants to watch TV for another channel.

    And it's just a matter of time until it is charged for using the internet too. "You may not ever use our internet site, but it's there for you, and it's independent. That'll be £140 please".

    They're a bunch of robbing cunts, and I'll never give them a penny. I'll rather be convicted than bow to the BBC.

    link to this | view in thread ]

  67. identicon
    James Gresham, 1 Nov 2008 @ 12:20pm

    Re: Davkaus

    The problem with this argument is that it assumes that you shouldn't have to pay for or contribute towards any public service that you don't use or like, and that's not the way society works.

    Regardless of whether you like the programming or not, it's hard to argue that having an independent adfree tv and radio broadcast service doesn't have some significant public value.

    link to this | view in thread ]

  68. identicon
    Krayol, 1 Nov 2008 @ 12:37pm

    I'm not sure whether the detector vans work, but I've heard of friend getting notified (some years ago) that they had been detected.

    Someone else said this too, but did you know that it is illegal for anyone in the UK to sell equipment capable of receiving TV signals without getting a confirmed address - the TV licensing people then check if you have a license.

    I received a letter threatening me because I bought a new TV when the old one "died" in a house move. The TV licensing people had been told to transfer the license to the new address, BUT they "had technical problems" and so I get a summons! One outraged phone call; they admit it was their mistake; threats ignored...no apology, just an "it happens" statement!

    link to this | view in thread ]

  69. identicon
    Davkaus, 1 Nov 2008 @ 1:15pm

    I agree that it's problematic to just say we shouldn't pay for something we don't use, for example, I'm very proud of our NHS, for all it's faults, and I certainly wouldn't want our Police force, or Fire service to have a callout charge.

    However, the BBC is very different to most public services, and I think a clear line has to be drawn.

    Life-saving, critical services are no problem, refuse collection, roads (trains would be nice, too, but let's not go there), but I don't think the BBC can put itself on a list of essential public services.

    If the channel were for education of information, I probably still wouldn't watch it much, but I wouldn't mind funding it, too much.

    The problem I have is that why should I pay for someone to watch Eastenders, Celebrities Dancing on Ice, or some immature cock on 6m per year chatting to people on a sofa of a Friday evening, in the name of a "public service"?

    Do you think we should have an independent "public service" newspaper, and you pay an annual fee to fund it, should you ever read one? How about books? Films at the cinema? How about a supermarket, if they suspect that you ever buy food, you pay them an annual fee, even if you don't want to shop there? It seems absurd, doesn't it? And yet we have to put up with the BBC.

    link to this | view in thread ]

  70. identicon
    Anonymous, 1 Nov 2008 @ 1:19pm

    Re: Re: TV detector vans don't exist

    You sir, are an idiot. A TV receiver is completely passive, It only detects the signal and does not "vibrate in sync with the incoming frequency", it uses integrated circuits to de-couple the video and sound signals from the carrier wave.

    The signals sent from a keyboard are through a ground-shielded coaxial cabel, which emits no radiation whatsoever.

    The only true thing you said was "read your PC monitor because of the signals emitted as it draws the display." This is known as Van Eck phreaking, but can be defeated with many modern LCD displays, If you are not watching it live, their is no way to prove you are illegally using a tv.

    link to this | view in thread ]

  71. identicon
    James Gresham, 1 Nov 2008 @ 1:44pm

    Re: Davkaus

    Obviously, it would be ridiculous for me to compare not paying for the bbc to not paying for hospitals or the police, so I won't. However, we do have various art endowments which sponsor art, music, films and literature, and which come out of our taxes, regardless of what we do for entertainment.

    The problem with the BBC is that it can't show the Proms and The Blue Planet and powerful artistic dramas, and then refuse to show Eastenders or reality shows.

    The supermarket arguement swerves a bit away from the issue - you've got physical goods, the products are mostly generic, you have to pay anyway, and the public benefit from another supermarket is questionable.

    Personally, I kinda like the idea of an independent newspaper along the same lines as the beeb (although i mostly get news from the web).

    link to this | view in thread ]

  72. identicon
    David, 1 Nov 2008 @ 1:46pm

    To detect or not to detect, that is the question

    I can't vouch for how effective present-day detector vans are, but some people on here seem to have their heads in the sand. Old-style CRT sets used to radiate all sorts of rubbish, which could be "seen" on a 'scope in the detector vans of the time and they could tell which channel was being watched and even where the set was located within the house. I well remember being given a demonstration of its capablities, as a youngster with an interest in such-like things, when one of the vans was in the neighbourhood some years ago. Whether modern, flat-screen sets throw out detectable spurious signals is probably debatable but I dare say the sensitive kit used these days can probably pick up anything that`s there!

    link to this | view in thread ]

  73. identicon
    Chris Morris, 1 Nov 2008 @ 2:27pm

    Its a myth - I am sure

    I worked in a magistrates court and sat through literally 1000's of TV licence cases and quite a few trials, not one during my experience was ever proved by a use evidence from a TV Licence Detector van.
    Almost all where proved on admission, or self incrimination, or by the inspector (no special powers) seeing or hearing the set in use.
    In my mind there is no doubt TV license detector vans are a myth, (even if they could work with some form of radiation detector from a CRT, they wouldnt work with LCD & Plasma screens).

    link to this | view in thread ]

  74. identicon
    Anonymous Cowherd, 1 Nov 2008 @ 3:06pm

    They're doing it wrong.

    If the government feels the need to snoop into what is going on behind peoples' closed doors in their houses even in the absence of complaints (or dead bodies), then they are doing something wrong.

    Furthermore, no method of detection is going to be very reliable in this day and age. Any method dependent on a particular sort of hardware, or on the use of reception antennas, can be defeated by using different hardware or getting cable or satellite. Driving by and looking for a "flickering glow" will have false positives from anyone who does not receive TV programming by airwave, cable, or satellite, but does watch DVDs, Blu-Rays, tapes, laserdiscs, HD-DVDs, or videos on computer (e.g. YouTube maximized full-screen or downloaded MPEGs and AVIs).

    Obviously, if they want money to produce state-produced TV content, they should get it from taxes. Equally obviously, if they want to make the added tax burden avoid landing on non-TV-watchers (all three of them), they should accomplish this by having a sales tax on TV hardware, specifically, devices with TV tuners (including cable boxes) and satellite dishes.

    Or they can figure out how it is that Canada manages to produce public broadcasting content without any snooping OR having any special taxes for the purpose. I think they use a combination of ordinary tax revenues and donation drives.

    link to this | view in thread ]

  75. identicon
    Iron Chef, 1 Nov 2008 @ 3:32pm

    Re: Re: Re: TV detector vans don't exist

    Agreed with Peet McKimmie.

    I remember a conversation with an old High School friend who said that it would be possible if there were 3 points for for triangulation purposes, but only one van only provides direction and not heading or elevation.

    You need three points of data to determine if there's a loss in bandwidth.

    To which I added: "Well, what if it's amplified, thru a signal amplifier how will you find that there is no loss?"

    With a snappy response, he said: "Well, if it's amplified, there will be an increase in the overall block of frequencies and therefore, you will still have to find the delta between the amplified frequencies... When you consume a signal, there's always a deficiency in that signal strength."

    "OK" I responded, "So let's say I put up an antenna, and re-broadcast the amplified frequencies, how would you compensate for that? At this point, I become a radiator,

    My use is probably 1dB at most.

    At this point he told me to read about Nicola Tesla and visit the Nicola Tesla Museum.


    Do note, this conversation happened about 20 years ago. I wonder what they are up to these days.

    link to this | view in thread ]

  76. identicon
    Relonar, 1 Nov 2008 @ 3:41pm

    Re: Re: Re: Re: TV detector vans don't exist

    well I am not an expert in signal capture or analysis, or have more knowledge in EM then what a 200 level physics course and an amateur license gets me.

    But, could you not put all your receiving equipment inside a grounded enclosure and place a choke on the antenna line to cut out all frequencies except those used by the station your tuning to? Would this not cut off any sort of detection they could use?

    And UK has a CB band on 27MHz that allows up to 4 watts without a license plenty good enough to drown out receiver noise (if any)...unless you have very sophisticated signal cleaning software, then maybe you might still be able to pick up the noise.

    A bit more drastic, but why not go all the way and place a grounded mesh around your entire residence (behind drywall, metal doors, window screen, and etc). although it may be difficult to get a cell signal afterwords.

    link to this | view in thread ]

  77. identicon
    Bill, 1 Nov 2008 @ 4:23pm

    Re: Licenses?

    I don't think the BBC has commercials that is why they charge a fee, if there were commercials, that would pay for the channel. Why do you think Top Gear gets away with trashing cars on the show, if there were sponsors no car manufacturer would let them have cars to test unless they agree to not say bad things about them. This is one reason why the American version of Top Gear that they are planning to make will suck.

    link to this | view in thread ]

  78. identicon
    Anonymous Coward, 1 Nov 2008 @ 4:30pm

    Currently Playing:
    The Source

    link to this | view in thread ]

  79. identicon
    Anonymous Coward, 1 Nov 2008 @ 5:17pm

    Re: Re: Re: Re: TV detector vans don't exist

    "The detector vans are completely unrelated to this. Detector vans are used to gather evidence before getting a court order."

    Except "detector" van evidence isn't admissible in court, if it were they'd have to disclose the full workings of the device to the defendants legal team so they could analyse it's effectiveness. This has never happened and never will because detector tools are bollocks.

    The BBC's own adverts even tell you how they catch "evaders", they spam threatening letters to millions of households in the hope some fool will actually pay them.

    link to this | view in thread ]

  80. identicon
    Anonymous Coward, 1 Nov 2008 @ 5:24pm

    Re: BBC

    "SKY TV - £480 a year
    BBC TV - £130 and no adverts."

    Sky TV - my free choice to decide whether I pay them a penny or not.

    BBC TV - I can be fined and imprisoned for not paying for something I don't want.

    "Pay the licence fee. It's superb value."

    If it's such superb value, people like you should pay more to have the BBC turned into a paid for subscription service where you don't pay, you don't get.

    Oh but then you'd have to pay a little extra and you're such a cheap bastard you don't want to, but would rather the rest of the British public subsidise your service.

    link to this | view in thread ]

  81. identicon
    Anonymous Coward, 1 Nov 2008 @ 5:32pm

    Re:

    "As a side note, I happen to somewhat agree with the TV license. In the past at least, it's let the BBC fund relative unknowns into making great shows since they don't have to worry as much about pandering to the masses since they technically don't need huge viewer ratings to get good money from advertisers. I just take extreme issue with the way the license is enforced."

    Let's just think about that for a minute. You're saying that you like the fact that the British public is forced to pay for a service they may, or may not want, in order to fund some crap that only a very small minority will like?

    Are you really that selfish?

    link to this | view in thread ]

  82. identicon
    Anonymous Coward, 1 Nov 2008 @ 5:37pm

    Re: Re: Davkaus

    "Regardless of whether you like the programming or not, it's hard to argue that having an independent adfree tv and radio broadcast service doesn't have some significant public value."

    Ad free, yes indeed so all those Apple product placements are just coincidence?

    Also, would you mind pointing me to this "significant public value" you talk about? Would that be the £6 million per year paid to Jonathan Ross?

    Why do people like you fear a subscription based service? Oh yes, you're a cheapskate who wants me to subsidise your service.

    link to this | view in thread ]

  83. identicon
    RabC, 1 Nov 2008 @ 7:07pm

    ADS

    Well I want to buy cheaper goods in the supermarket ones that dont pay for over priced ads and sponsorship of the prima donna's in the FA. DO i get the choice ? not likely.. Ross is overpaid.. 1 could smarm at twice the speed for half the money with double the effectiveness!

    link to this | view in thread ]

  84. identicon
    Roland, 1 Nov 2008 @ 8:22pm

    modern construction

    Modern construction includes thermopane windows which have a thin transparent metal film applied in a vacuum chamber to the glass, to reflect Infrared. And many houses have insulation that includes a foil layer. Shouldn't be too hard to turn your house into a Faraday cage. Then the vans couldn't pick up any IF radiation from your TV, especially if the antenna feedline has a high-pass filter. And what if you only watch satellite? These vans are rubbish.

    link to this | view in thread ]

  85. identicon
    Mark Regan, 1 Nov 2008 @ 8:36pm

    They'll never get me

    When I built my house, I put up steel plates between the wallboard and framing to create a "RF Quite Zone" -- and it has worked so far. No visits from the BBC or the local constable.

    And I used scrap steel to keep the cost down, and after twenty years I've about saved enough to cover the upfront cost. The hard part is the windows. I have to use those "coated" or "treated" plastic sheets. I think they have some sort of thin aluminum coating -- but the rooms get pretty dark on cloudy days.

    You colonists have it nice -- getting to watch all those Palin commercials instead of having to pay BBC's TV tax.

    link to this | view in thread ]

  86. identicon
    Xavier, 1 Nov 2008 @ 10:46pm

    Re: Re: Re: Re: TV detector vans don't exist

    Good job, Iron Chef!

    Your right, you do need 3 points to triangulate a signal, so theoretically, you would need 3 vans to accurately find a pirate. In fact, most GPS systems rely on 5-7 beacons to accurately determine location with altitude (Helpful for multi-level apartment complexes)

    Still, this technology is even quite dubious- requiring resetting of the onboard cesium atomic clock a nightly basis because they loose micro seconds every day. :-)

    But as you shared, it seems like overkill considering the simple $10 hardware people could purchase to get around it, then there's potential repeaters which re-broadcast the channel from multiple directions. A little research into OFDM could provide you with some of the physics involved with multipath frequency interference. Bad stuff!

    Still, it seems the 20-year old conversation you had is right on.

    Not to interject another theory, but how would this work with a person enjoying non-terrestrial programming such as SkyTV without having 2 points in space? (Smile)

    My guess is that it can't happen considering the transmitting element is some 30 miles above earth, and if your looking to find a dB loss of sub-1dB, it would require measurement instruments possibly in separate countries, if not in outer space! If the goal is to find infringement within the UK, at this point, the requirements of instrumentation possibly exceed those of current human technological capability.

    Considering the end goal of Government to capture a $100 tax, it's quite dubious that technology of this sort is even available, because it doesn't get tied to a contract with something that makes a big boom.

    I have to say, your friend was quite smart, and like yourself, I wonder what you and the friend who inspired you to think this way are both doing.

    Surely when you researched Nicola Tesla, you found this Quote:

    "Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality."

    I can only guess you've seen this before. :-)
    But overall, it seems like this tax is all based on the honor system, and has a little fear mongering attached.

    Don't worry.
    This level of tech doesn't exist.

    Xavier

    link to this | view in thread ]

  87. identicon
    MichaelK, 1 Nov 2008 @ 11:27pm

    There's no fancy equipment in the van

    Just some chap with a sonic screwdriver.

    link to this | view in thread ]

  88. identicon
    Peet McKimmie, 2 Nov 2008 @ 2:01am

    Re: Re: Re: Re: Re: TV detector vans don't exist

    Your right, you do need 3 points to triangulate a signal, so theoretically, you would need 3 vans to accurately find a pirate.


    Nope. This is a fallacy propagated by sloppy TV scriptwriters. You need two points associated with two headings; it's called "triangulation" because where the lines cross becomes the third point of the triangle.

    link to this | view in thread ]

  89. identicon
    Anonymous Coward, 2 Nov 2008 @ 3:37am

    Re: Re: Re: Davkaus

    "Let's just think about that for a minute. You're saying that you like the fact that the British public is forced to pay for a service they may, or may not want, in order to fund some crap that only a very small minority will like?

    Are you really that selfish?"

    Actually, the BBC gets quite a large amount of the viewing public - BBC 1 claimed 19.4% of total viewing in September and 23% in August, more than any other channel. Also, the TV Licence pays for radio services as well - int the last quarter measured, BBC radio stations had a 65% reach and a 54.9% listening share.

    "Ad free, yes indeed so all those Apple product placements are just coincidence?

    Also, would you mind pointing me to this "significant public value" you talk about? Would that be the £6 million per year paid to Jonathan Ross?

    Why do people like you fear a subscription based service? Oh yes, you're a cheapskate who wants me to subsidise your service."

    1)From the BBC's editorial guidelines:

    "Product placement

    We must never include a product or service in sound or vision in return for cash, services or any consideration in kind. This is product placement. It is illegal to make any such arrangements in the EU."

    2)Friday Night with Jonathan Ross won the BAFTA for Best Entertainment Performance in 04, 06 and 07. He hosts multiple programs on both TV and radio. His ratings are consistently high. He was also the centre of a very public bidding war between the BBC and ITV which pushed his contract price up a lot.

    3)The only BBC service I use with any regularity is BBC News on the internet, which I could get for free without a TV licence. I listen to a commercial radio station in the car, and don't watch very much TV, with maybe 2 BBC programs a week at the very most. I am not being subsidised - if anything I'm doing the subsidising.

    link to this | view in thread ]

  90. identicon
    Anonymous Coward, 2 Nov 2008 @ 7:03am

    Register when you buy

    I don't think it's a legal requirement for retailers to send peoples addresses to the BBC when they buy a TV. If it is then almost all retailers need to be informed. You can buy a TV in Tesco and they certainly don't take details.

    link to this | view in thread ]

  91. identicon
    Mike, 2 Nov 2008 @ 9:27am

    Re: Re: Re: TV detector vans don't exist

    link to this | view in thread ]

  92. identicon
    Jeff Rife, 2 Nov 2008 @ 9:34am

    Re: Re: Re: TV detector vans don't exist

    Every electronic device leaks, and do some reading about tuners and see how they work by matching the desired reception frequency, which causes a very small resonance broadcast at that same frequency.

    As for picking up signals from keyboards:
    http://lasecwww.epfl.ch/keyboard/

    LCD displays also emit enough to be detected remotely:
    http://www.cl.cam.ac.uk/~mgk25/pet2004-fpd.pdf

    Do some research before you call someone an idiot so you don't end up looking like one yourself.

    link to this | view in thread ]

  93. identicon
    Jeff Rife, 2 Nov 2008 @ 9:39am

    Re: Re:

    You missed an indirection.

    RADAR works by blasting you with energy.

    Radar *detectors* work by seeing that energy...definitely trivial.

    Radar detector *detectors* can locate the radar detector by the IF it leaks when trying to tune the radar signal, just like you can detect a TV tuner.

    link to this | view in thread ]

  94. identicon
    AnoMan, 2 Nov 2008 @ 1:50pm

    That's really funny. We had the same legend in germany ages ago and it is just a fake story. How can you detect a single signal in populated area? You could detect the area but never the apartment. Or do you want to check 100 apartments to find ONE person ?

    Good luck... this is a myth.

    link to this | view in thread ]

  95. identicon
    JohnnyHeavens, 2 Nov 2008 @ 2:15pm

    LOL @ TV detectors and the BBC

    This is somehow the funniest, saddest, and dumbest story (somehow all at once) I ever read.

    Seriously? 94 comments so the must be something to it but this sounds like a good enough reason to revolt. Utterly amazing.

    link to this | view in thread ]

  96. identicon
    Kilgore Trout, 2 Nov 2008 @ 2:49pm

    Re: Licenses?

    DirecTV. Dish Network. Charter. Bright House. Verizon Cable.

    I'm assuming you have none of these, or their brethren?

    link to this | view in thread ]

  97. identicon
    Cpt. Obvious, 2 Nov 2008 @ 3:24pm

    S'all about noise

    They detect the noise generated by the receiver as the transmitted signal wattage jams into a suppressor device and fizzles. This much has been known for years now. Why is this being brought to light again ?

    I suspect they don't bother with the vans now cos the myth is enough of a deterrent, and the database that automagicly sends out 'why ain't you paid?' letters is enough to kick peoples arse into buying a license.

    link to this | view in thread ]

  98. identicon
    Peet McKimmie, 3 Nov 2008 @ 2:50am

    Re: Re: Re:

    You're right, sorry. It was late. @'.'@ Take one "Detector(s)" off each side of the argument. :-)

    link to this | view in thread ]

  99. identicon
    Twinrova, 3 Nov 2008 @ 4:09am

    So, after reading all the comments...

    ...when does the second season of Primeval start? That's a good show! I caught it on BBC America (w/adverts).

    link to this | view in thread ]

  100. identicon
    David, 3 Nov 2008 @ 5:12am

    @Daniel Kaiser

    >Just wrap your house in copper mesh, no RF no problem, of course it will keep your cell phone from working.

    ... and your TV.

    link to this | view in thread ]

  101. identicon
    David, 3 Nov 2008 @ 5:18am

    Re: Re: Re: TV detector vans don't exist

    @ PaulT

    >...and how does that detect whether the TV is licenced?

    Don't be silly. They already know which addresses are licensed. They look for IF emissions (and this is technically pretty easy) from the unlicensed minority.

    What they can do if they detect a TV, beyond hassling you, I don't know.

    BTW, I'm a long-term non-telly-owner. They send enquiry forms on which you can declare you don't have a TV but, in my experience, they ignore them.

    link to this | view in thread ]

  102. identicon
    Anonymous Coward, 3 Nov 2008 @ 5:20am

    I have to pay a full TV license for my USB tv tuner. The thing is, I can't PICK UP ANY BBC CHANNELS!

    However this is not a valid argument against paying it. It's a tax run by a non-governmental organisation.

    link to this | view in thread ]

  103. identicon
    Anonymous Coward, 3 Nov 2008 @ 6:36am

    Back in the day before Cable they did the same thing in Canada. I had a good talk to my parents about how it technically could not be done to which dad had photos of the van as it drove by the house. Not sure when it was phased out and my parents are no longer alive to take up the conversation.

    link to this | view in thread ]

  104. identicon
    BTR1701, 3 Nov 2008 @ 7:07am

    Re: Re: Detector vans

    > we were talking about tv cards in a PC and
    > whether or not they'd bypass the detector vans

    With services like iTunes gaining in popularity, you don't even need a card anymore for your computer. Just download the shows as video files.

    I did a quick count a few weeks ago and 85% of the shows I watch regularly can now be found on iTunes. I don't know what the cost of a yearly TV license is in Britain but it might be worth looking into if buying the shows off iTunes is cheaper than paying the annual license fee.

    link to this | view in thread ]

  105. identicon
    BTR1701, 3 Nov 2008 @ 7:17am

    Re: Re: Re: TV detector vans don't exist

    > it's cheap and easier for them to assume that
    > every house has a TV then deal with complaints
    > from those who don't, than it is to actually
    > have an army of the vans checking every street
    > in Britain.

    And even if they did work, I can't imagine how they could zero in on just one TV in an entire apartment building full of TVs. How do they distinguish your TV from all the others in close proximity?

    And what about the people who don't live in cities? Seems like these vans wouldn't do much good if the closest they could get to the residence is several hundred yards away on a country road. (Unless these TV inspectors are allowed by law to enter private property. This being the UK, they're a lot more likely to allow that kind of government intrusion than America.)

    link to this | view in thread ]

  106. identicon
    BTR1701, 3 Nov 2008 @ 7:34am

    Re: Detector Vans and Licenses

    > If you have a TV capable of receiving broadcast
    > signals and it is connected to an arial then
    > you will have a hard time proving you don't
    > watch TV.

    And this is why the presumption of innocence is such a good thing. In America, I wouldn't have to prove I wasn't watching TV. The government would have the burden to affirmatively prove that I was.

    link to this | view in thread ]

  107. identicon
    BTR1701, 3 Nov 2008 @ 7:39am

    Re: Re: They use them in the USA too.

    > NOBODY can enter your property except police,
    > and then they require at the very least, probable
    > cause.

    No, they need a warrant. Probable cause is what they have to show the judge to get the warrant. Probable cause alone won't suffice. They have to take that extra step of having a judge agree that it's valid and issue the paper accordingly.

    link to this | view in thread ]

  108. identicon
    darkspur1, 3 Nov 2008 @ 10:24am

    TV detector vans don't exist

    Anonymous Coward is a know nothing cunt who proves the rule that a little bit of knowledge is dangerous. Listen to his half-baked rantings and pay the price at your peril.

    I have operated one of these detector vans that supposedly dont work, many many times. Those who wonder how a TV set can be pin pointed in a block of flats amongst many other TV sets, well there is a device called a hand-held detector.
    Believe me it all works, but it is mostly unnecessary these days apart for PR purposes as the Licensing Authority rely on a very, very comprehensive nationwide database which holds every single address in the country, including mobile homes and university campuses.

    People like Anonymous Coward tell half the story when claiming that TV licence officers come round and tell lies and trick their way into people's premises. Absolute rubbish. Believe me, their feet would not touch the ground.

    Dont listen to this idiot, he'll get you into trouble.

    link to this | view in thread ]

  109. identicon
    Anonymous Coward, 3 Nov 2008 @ 12:55pm

    Re: Re: BBC

    Just make it very uncomfortable for them to be in your house. Walk around naked while they are there, and follow them -very- closely as they search.

    link to this | view in thread ]

  110. icon
    John (profile), 3 Nov 2008 @ 1:41pm

    Occam's razor...

    ... or the simplest explanation is probably the correct one.

    Which is more likely?
    1) The BBC sends notices to every household, demanding a payment, irregardless of whether or not that household actually has a TV. If there's no TV, then the people can argue with the BBC.

    2) The BBC has the technology, the ability, and the money to outfit a FLEET (not just one, but a FLEET) of vans with ultra-sensitive electronic equipment.

    This same equipment can differentiate between a TV signal and all electronic devices, including PC monitors, cell phones, etc... AND the equipment can "see" through any lead pipes or stone walls which block other signals, such as cell phones.
    This equipment can also determine the exact location of each signal and it won't get confused by overlapping signals coming from every house in the neighborhood nor by people living above one another in apartments or condos.

    And the BBC has the manpower to send out in vans to patrol the neighborhood, listening for these electronic signals.

    So, then, is the BBC the biggest buyer of vans in the UK? Is there some car dealership that has an exclusive deal with the BBC to supply them with these super-vans? Can GM get a contract with the BBC? It might just give them the cash they need to recover!

    And even assuming that the BBC does have the manpower to run these patrols, how long would it take to patrol just London? How about all of England? Are these patrols monitored by the people in the neighborhood? Could someone watch for the van, turn their TV off, then turn in back on when the van passes by?
    If the "busybody" people in the neighborhood know what time you walk your dog everyday, wouldn't they notice an unknown van driving through, very slowly?

    And are these vans also equipped to connect to a database to check who's licensed and who's not? Do people ever get a "false positive" from these vans, when the van shows they have a TV signal and no license, but they actually do have a license?

    Yep, this all makes perfect sense to me. Obviously, the BBC's main business plan is to patrol the streets with military-level technology rather than provide television programming.

    link to this | view in thread ]

  111. identicon
    Anonymous Coward, 4 Nov 2008 @ 5:06am

    american cost

    I looked online at the british site, it costs 139.50 british to get their TV License, that translates to about $222 american! Holy Cow!

    link to this | view in thread ]

  112. identicon
    Now safely living in the USA, 5 Nov 2008 @ 5:28pm

    Re: Re: TV detector vans don't exist

    The old detector vans worked by picking up the timebase radiation from the CRT TV................BUT plasma and LCD TV's do not have a timebase so now all they rely on is the voter registration list. Before getting my visa to come here, I lived in a bedsit house. The hallway was awash with letters from the TV Licensing people some addressed to individuals who had moved on or simply to the room number. It is obvious that detector vans did exist in times past but now the licensing people rely on a mixture of bluff, psychology, fear and bullying to collect the fees. My friends over here just cannot understand having to have a license to watch TV.
    A contented Brit ex-pat

    link to this | view in thread ]

  113. identicon
    Michael Foord, 7 Nov 2008 @ 8:34am

    Re: It's done at the point you buy the TV

    That's one of the mechanisms. I recently bought a large LCD TV (which I use as a computer monitor). I regularly get the threatening letters - but I've still never had one of the promised visits.

    link to this | view in thread ]

  114. identicon
    Michael Foord, 7 Nov 2008 @ 8:36am

    Re: Occam's razor...

    They know who is licensed and who isn't - so they only need to send the vans to specific locations. They have no need to patrol the whole country.

    link to this | view in thread ]

  115. identicon
    wayne yardley, 15 Nov 2008 @ 8:46am

    Dection of tv sets in operation legal useage or not.

    Having workeded in the electronics industry for more than 30 years I would suggest that an simple am radio could be used to detect the harmonic radiation given off from an tv set in operation.I am sure that detector type radio equiptment is being used.By knowing the number of tv sets in operation at an given residence.Those who wanted to know wheter or not it was an legal operating unit or not would compare data submitted by the tv licensee and set up the detection equiptment to make its determination as to wheter or not it was an legal tv set in operation.

    link to this | view in thread ]

  116. identicon
    Anonymous Coward, 18 Nov 2008 @ 4:13pm

    Re: Re: Detector vans

    Are you talking bollox or what. When I contacted TV Licensing requesting for them to stop bothering me at my then new address (I DO NOT watch telly - it's 5 channels of complete crap) I was informed, very politely, that the most effective way of assuring compliance with TV Licensing Regulations was to bambard people with BOLLOX about Detector Vans!

    link to this | view in thread ]

  117. identicon
    Richard, 8 Dec 2008 @ 9:01am

    Re: Re: Re: TV detector vans don't exist

    I understand it's about 30 to 40MHz but there may be more than one. Back to the textbook to revise for my radio comms exam in which I'm expected to know all these numbers in case a transmission I make is on the same frequency and can swamp the circuitry inside someone else's telly!

    10.1MHz is a typical FM Radio's intermediate frequency. It's also one of the amateur radio bands so you can get strong signals - Morse code or data - on those frequencies. If your FM radio blanks out to the sound of Morse Code you may have a radio amateur near you who needs to check their equipment (or you yours). It's not that likely to happen. Modern radios/TVs have protection as part of the appropriate directives for where you live.

    The IF circuitry in the telly will radiate a little. There are lots of other signals in there too. One fairly likely to radiate is the tuning oscillator which will vary with what it's tuned to. It's frequency is most likely the difference between the station you're receiving and the IF. If they can pick it up they can tell or at least guess what channel you're watching. That one may radiate up the antenna feeder a little depending on the circuitry. The TV van I saw demo-ed once claimed to be able to tell what channel the TV was tuned to.

    Accuracy in location needs a directional antenna, the size of which depends on frequency they're looking for. That said, they can move the van so could theoretically look for strongest signal even with a fairly poor antenna.

    Some things that can mask signals, at least below 30MHz, are those computer network over mains adapters. They also annoy local radio amateurs because they wipe out huge ranges of the useful radio frequencies for long range communication and can easily swamp a shortwave radio receiver for quite some distance away. If the IF is towards 40MHz, or it's the tuning oscillator much higher, then these won't help.

    link to this | view in thread ]

  118. identicon
    Richard, 8 Dec 2008 @ 9:03am

    Detecting weak signals amongst off-frequency noise.

    Have you played with PSK31? Very impressive - picking out weak but narrow band signals amongst heavy noise even on a cheap kit receiver. Even the cheap kit receiver happily selects out strong signals quite close to its tuned frequency.

    link to this | view in thread ]

  119. identicon
    Richard, 8 Dec 2008 @ 9:16am

    Re: Re: Re: Re: TV detector vans don't exist

    Reading on with the thread - I'd have thought that picking up the scanning signals in the tube would be easier. They'd be pretty strong and badly shielded in a TV set typical of the 70s and 80s when I used to know about detector vans.

    link to this | view in thread ]

  120. identicon
    C, 16 Dec 2008 @ 11:01am

    TVLA

    Do you know you don’t have any police powers as you claim to have, as you think you caution people under The Police and Criminal Evidence Act 1984 (PACE). The occupants don’t have to say or sign anything.

    You can only obtain entrance to a property by invitation only.
    You cannot force your way in to a property this would be trespassing.

    There are two cautions under PACE. One is for use when you are being arrested, for a mandatory interview, that is what TVLA reads you but they cannot arrest you or mandatorily interview you.

    There is a second milder caution under PACE for situations where an investigator is not arresting and has no RIGHT of interview, and that one allows an absolute right of silence and you can slam the door in their face with no consequences for your defence.

    You are deliberately misleading members of the public with your poorly worded letters, making it looks like you have police powers and authority. Well the truth is you don’t you work for a private company, not The Crown.

    If you have these detection vans and hand held detection devices to detect television signals, why do you continue to send out letters to vacant properties and properties that don’t have a TV, stating they don’t have a valid TV license.

    If you had these equipments you would not have to send out letters or have a representative from TVLA to visit these vacant properties and properties that does not have a TV.

    We all know the fact a TV license detection van only has an aerial on top of the roof. There is nothing inside that van only the driver.

    The truth is that this equipment never existed in the real world, they are just a publicity stunt and propaganda to scare members of the public.

    Under the Freedom of Information Act 2000 the TVLA and BBC refuses to release information how this technology operates.
    The truth is the technology never existed that is why the TVLA and BBC never have any information about to release about this technology.

    Well you have to redraft your standard you sent out to members of the public with the following amendments:

    • The TVLA can only obtain entrance to a property by invitation only.

    • The TVLA cannot force their way in to any property this would be trespassing.

    • The TVLA don’t have any police power at all, they are a privatised company and not The Crown.

    link to this | view in thread ]

  121. identicon
    C, 16 Dec 2008 @ 11:08am

    Re: Re: TV detector vans don't exist

    are you television technician?

    you seem to be very technical.

    If this is true the vans this technology why do they need to knock on your door?

    The Post Office used to run the TVLA. I was informed by staff at the GPO it is a van with an Ariel on the top of the roof and just a driver. There was nothing inside this van.

    link to this | view in thread ]

  122. identicon
    C, 25 Dec 2008 @ 12:14pm

    Re: Re: TV detector vans don't exist

    if it really works.

    Why does the TVLA send thousands of letters to vacant addresses or addresses that does not have TV set?

    They all just empty threats as there is no one to read their letters.

    Feel free to reply

    link to this | view in thread ]

  123. identicon
    Beltronics radar detector, 8 Jan 2009 @ 5:53am

    Was searching for radar detectors and came across TV detectors, but still loved getting here!

    link to this | view in thread ]

  124. identicon
    Colin, 10 Jan 2009 @ 4:55pm

    Re:

    A unicorn is a mythological creature.

    link to this | view in thread ]

  125. identicon
    Lee McClane, 3 Feb 2010 @ 7:55am

    Re: Detector vans

    They don’t exist.

    How come nobody has ever been prosecuted by one and presented with the evidence.

    Under British law all evidence must be presented to the defence before a trial. If you are charged with speeding, drink driving, or faced with forensic evidence then the prosecution has to explain the process used to gather that evidence to the court.

    The defence can then cross examine and challenge any such evidence and its accuracy.

    If anyone had ever been presented with this evidence before or during a trial then there would be some record of it. I’m sure as with motoring offences and accident claims there would be several law firms claiming that they can have these charges thrown out……for a fee!

    It wouldn’t be a case of “The van said they received a signal your worships” and then you got a guilty verdict. You would be allowed to challenge the accuracy of the evidence. In order to do that the Crown would have to explain exactly how the detector van worked, and the technology used.

    Just as they would with Gatso cameras or police VASCAR speed detection systems, documentation proving accuracy and regular testing would have to provided and proved.

    They would have to establish and prove that the device was “Home Office Approved” In order to get such approval any device used must undergo regular testing to prove its accuracy. Just like a certificate of calibration.

    link to this | view in thread ]

  126. identicon
    sm, 5 Jan 2011 @ 11:46am

    The fact that the government could require citizens to license a television is UNTHINKABLE to most Americans (what if you only want to use the television to watch DVDs, or satellite programs, for example, and don't watch BBC at all)... LET ALONE the idea that government goons could drive around in vans and SPY on citizens to try to catch them with an "illegal" TV (hard to say without laughing). Just another example of how the UK is the Big Brother state that freedom loving Americans fear their own country is becoming slowing but surely.

    link to this | view in thread ]

  127. identicon
    the north face, 6 Jan 2011 @ 7:49am

    the north face

    Tone has not finished school north face the next day north face on saleI step onto the podium north face on salelooked around the room and found a few the north face cute cards. Those greeting cards or the northfacestanding on your desktop north face on saleor lying on the owner of the palm. Are artful in Eagle north face on north face jacketssaledancing bees butterflies north face on salecolorful image with different flowers north face on salea naive north face on saleclumsy blind black bear north face on salethere are bright green Christmas tree ... ... I quickly went to the few cards creator before north face on salecan not wait to get them in your hand north face on saleshow to everyone north face on salethat outlet north face
    beautiful image north face on salewith inlaid mother of the above letter from the kind words north face on saleeven I have moved north face on salejust like my children to write Like me north face on saleread them north face on saleand my heart as sweet as honey to eat north face on sale"Wonderful!" "How beautiful!"

    link to this | view in thread ]

  128. identicon
    HAROLD, 28 Jun 2012 @ 11:29am

    NO LICUNCE LOL

    NO LICENCE FUCK BBC AND TVLA LOL

    link to this | view in thread ]

  129. identicon
    IVOR ALLISON, 18 Jun 2013 @ 1:27pm

    The tv detector vans USED to exist - there is a video shot during the 60s showing an operator looking at a 2 inch screen saying "they are watching Columbo on ITV at number 28 and the tv is in the front room . Well, if you see the "equipment" then its very obvious that they cant and never could do that. With modern LCD/LED tvs and the plethora of spurious signals it is quite impossible to detect any non licence payer. The way that its done is that a database of tvs sold and to whom is compared with a database of licensed tv sets and those homes that pop up are visited by an inspector. Simple.

    link to this | view in thread ]

  130. identicon
    m p, 10 Jul 2013 @ 12:15pm

    No way to detect tuner. Tuner from IF to RF reverse isolation is over 80dbc at such low freq . Further Tuner generally have a ground inductor complete high pass this low freq.

    Analog TV need 30dbc SNR to demodulation.

    Be clever and dont be fool.

    Best detector equipment is from Agilent,
    not military/goverment.

    10 year design of silicon Tuner by me

    link to this | view in thread ]

  131. identicon
    colin, 15 Aug 2013 @ 1:44pm

    Re: Re: TV detector vans don't exist

    BULLSHIT.

    link to this | view in thread ]

  132. identicon
    annon, 4 Jun 2014 @ 11:25am

    TV Detector Vans

    its horse shit, it says right on the TV licencing website that "you do not need a licence if you use a TV to watch dvd's or use a games console", as long as you do not watch live broadcast TV!!! so how can they tell if your watching dvd's or live broadcast? its all just propaganda bullshit!

    link to this | view in thread ]

  133. identicon
    Ben Hutchinson, 6 Dec 2014 @ 5:31pm

    If these vans work, they would work like this

    First let me explain a bit about how a TV set works. A TV set uses a downconverter with a local oscillator to convert a signal from one frequency (carrier frequency) to a lower frequency (intermediate frequency). When you change the channel on your TV, you are changing the frequency of the local oscillator. The frequency of the TV carrier signal for a given channel, minus the frequency of the local oscillator, equals the intermediate frequency. The intermediate frequency is supposed to be constant, so the local oscillator frequency is always the carrier frequency of the current channel, minus a constant value. If the intermediate frequency is 50MHz, then that constant value is 50,000,000Hz. If you are trying to tune into a channel who's video carrier frequency is at 400MHz, the local oscillator will be set to 350MHz. When a sinewave at 350MHz is multiplied (the first action performed by the downconverter) with by a sinewave at 400MHz, the result is two new sinewaves. One will be at the difference frequency (50MHz, your intermediate frequency), and one will be the sum frequency (750MHz, an unwanted signal). The output off this multiplication is then put through a lowpass filter, which passes the 50MHz intermediate frequency signal, and blocks the higher frequency signal (this filtering is the second action performed by the downconverter).

    By using an ultra-wide-band TV receiver (one that can "see" every signal simultaneously in the TV broadcast part of the RF spectrum), a TV detector van can tell not only if a TV is turned on, but also what channel it's tuned to. If there's a strong signal at 400MHz, and a weaker signal at 350MHz, they will know that you are tuning into the channel at 400MHz. If you are using your TV as a monitor for playing video games or for your computer, then the local oscillator will be turned off, and the TV detector van will see that your TV is not set to receive any channel, so they will know that you are not illegally dodging license fees.

    And don't think that they won't be able to pick up your signal if you use a modern digital TV. They still will pick it up. In analog TV sets, the intermediate frequency signal is then amplitude-demodulated to extract the baseband video signal, which is then amplified and directly sent to the video controller circuits (electron beam strength controlling circuits on old CRT units, or an analog-to-digital converter on modern units that outputs a digital signal that goes to the microcontroller that operates the LCD panel on modern units). On digital TVs, the intermediate frequency is demodulated using special techniques (not straight AM-demodulation) to extract the MPEG2 encoded digital video signal, and this is then sent to the MPEG2 decoder and microconteroller that operates the LCD panel. However, in ALL TVs (old and new) there is a local oscillator, which is required to produce an intermediate frequency signal for further processing, and this will always be detectable using sensitive RF surveillance equipment like those used by the TV licensing enforcement vans.

    link to this | view in thread ]


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