How do radar detector detectors work?

I was under the impression that Radar detectors were passive by nature, so I'm a little confused on how the science works in a Radar Detector Detector... Anyone care to point me in the right direction?

I assume that the mere detecting of the radar wave changes any response that you get, so you could detect it like that, but it just seems that the change would be so tiny as to be very hard to detect.

?

Paul.

Radar detectors, TV tuners, and other such gizmos use a "phase locked loop" to latch onto and follow the frequency of the signal. This requires the tuner to have an internal oscillator running at the same frequency as what it's trying to tune. Those oscillators give out trace RF emissions. That's what radar detector detectors pick up on. Likewise, it's what the roaming TV detector vans in the U.K. use to notice that you have a TV set where you didn't pay your TV tax.

Worth noting that there are ways to make the oscillator harder to detect. Those of us part of the V1 cult appreciate Mike Valentine's efforts in this regard.

Okay, then. Follow up question.

There are radar detectors which claim to be detector-detector prrof. As I understand it, they do this by shutting themselves down when in the presence of a detector-detector. How do THOSE work?

A radar detector-detector-detector? Then do the cops get a detector-detector-detector-detector??

check out this excellent radar test site: speedzones. Unbiased testing from all sides... and it includes a section for radar detector detectors. No recommendations, just test results... good stuff.

Cool article, thanks!

They work the same way again, one more layer.

But the current Australian RDDs seem to be tuned to nab *everything* that's out there right now, including *all* of the so-called RDD-proof RD's.

Cheers

So RDD's actually generate Radar frequency emissions - I see!

Thanks for the info - just what I needed.

I always thought that the TV detector vans were detecting EMF output from screens - I can see how that might work.

I was also told by someone that 90% of the TV detector vans are actually empty - just there to 'scare' people into buying licences.

Cheers,

Paul.

Yeah, cool site. Thanks for the link!

I was also told by someone that 90% of the TV detector vans are actually empty - just there to 'scare' people into buying licences.

It wouldn't surprise me at all if the figure was 100%. Has anyone ever actually seen one of these vans, except on adverts?

Peter

Yup, when I was at university - a van pulls up into the Car Park for the hall of residence with TV DETECTOR VAN spashed all over the side.

There was literally an exodus to the local postoffice - funny really.

Paul.

Sounds like the perfect application of an empty van, students are easily scared.

Did this van have many aerials, and a chap from the Ministry Of Ousinge?

Apparently they have a few different technologies in the van - one is to detect the flyback in the CRT. I think this is mainly just additional to the IF detectors.

It has long been known that 9/10 detector vans are fake - I read a report a few years back thay quoted somebody who was involved in painting the wooden aerials silver! Somebody also inspected a van at a display outside a railway station - there was a nice 60cm Sky dish on its roof and bench seats in the back behind the tinted glass!

These days it's much easier for them to cross reference the database of licensees against the Royal Mail database and mailshot anybody who hasn't got a license. Friends of mine (both retired programmers) have never owned a TV but used to get regular letters and visitors accusing them of various things, until they wrote back saying that if they were contacted again they would sue for harrassment. It worked!

At the office we got a letter a few months back implying that we legally had to sign a form saying we didn't have a TV on the premises. We got a phone call a week or so later asking why we hadn't returned it, and when I said we are willing to fill it in at our standard rates they just said an "enforcement officer" would visit soon. I've not seen them yet! I wouldn't let them through the door without a warrant anyway, and they would be wasting their time because we don't have a TV here!

Gareth

There was literally an exodus to the local postoffice - funny really.

We just hid the TV under my bed until the van had gone away again. Not that I actually saw the van -- we just got a phone call from the other side of campus telling us that it was on the prowl -- so we just hid the TV for the rest of the day.

I wouldn't let them through the door without a warrant anyway, and they would be wasting their time because we don't have a TV here!

They don't need a warrant -- like Customs and Excise, they have a statutory right of entry.

I didn't have a TV for years, and used to get letters (ranging all the way from very polite to very impolite) about once every four weeks. Once I tried ticking the "I don't have a TV" box and sending it back, but as all that did was increase the gap between letters to six weeks ("It's now time to update our records") I didn't bother again. One letter even alleged that an enforcement officer had visited but I was out.

Peter

To the best of my knowledge the TV gestapo has a grand total of 2 actual detector vans in the entire country. The rest are all dummies. They also can't 'detect' tv usage if it's via a PC in most cases.

They work mainly by looking for leakage from the TV flyback signal, at the horizontal line frequency of 15.7 kHz. Newer equipment also looks for TV tuner local oscillator leakage, but this is less easy to detect.

Most of the time, they simply work on the basis of bothering people who live at an address where there is no license registered, on the basis that everyone must obviously have a TV, and if there is no record of a license being assigned to your house, you're cheating them. Various friends of mine who don't own, and have never owned any form of TV, video, etc (yes, there are still a few), STILL get letters quite regularly complaining that they haven't paid for a license.

pca

They don't need a warrant -- like Customs and Excise, they have a statutory right of entry.

As far as I can find out, this is incorrect. The information I have is that they must have a warrant to enter, and they must be accompanied by a uniformed police officer.

pca

As far as I can find out, this is incorrect. The information I have is that they must have a warrant to enter, and they must be accompanied by a uniformed police officer.

Oooh yes, you're right. Looks like I fell for an UL. According to famed constitutional lawyer Richard Stilgoe, only Customs officers and officers of gas, electricity and water boards have that power -- and that was in the 70s, of course, so I don't know whether officers of deregulated power companies have any such power.

Peter

We just hid the TV under my bed until the van had gone away again.

Our halls of residence (Stephenson Hall, Sheffield) JCR ran a scheme. At the beginning of the year you sold your TV to the JCR for a pound, the JCR would then rent the TV back to you for the rest of the year for a pound, the JCR had a TV licence.

No idea whether the scheme had any legal basis, we never got raided...

I don't think thats actually legit. It's the property itself that needs the TV license and each individual room is classed as a seperate residence.
TV licensing came around at university once and stuck up huge posters everywhere telling people about how they're not covered etc... and they'll be checking. I don't recall anybody ever coming around or acting suspicous outside with a van though.

When I was off campus living in a flat some guy knocked on my door saying he was from TV licensing and if I had a TV. I said no and he said oh okay and left

A battery powered TV however is covered under your home one though. Not sure what they'll say to a inverter and a huge battery though

A battery powered TV however is covered under your home one though. Not sure what they'll say to a inverter and a huge battery though

They have got that one covered. Not only does the set need to be solely battery powered but the batteries also have to be internal.

Wow. I had no idea there was a TV tax in the UK. That would never fly in the US. What exactly is the tax for? I'm guessing it goes to pay for the BBC and other aerial channels? How does it work if you have cable? Excuse my ignorance... =]

It's used to fund the BBC. The other channels are all advertisment funded whilst the BBC channels don't have any adverts.
You still have to pay it even if you've got cable/satelite. I think a guy few years back managed to avoid the licensing fee because he only wanted to watch videos and had all of the tuners removed. They took him to court for it but he won.

That would never fly in the US.

I guess you never heard of PBS.

Last i heard... PBS didn't send around vans threatening to fine you if you didn't donate during the pledge drive!

...yet...

Some people hate the TV licence and the fact that it funds the BBC. To me however the world would very much worse for the loss of the BBC. What would I do without my daily intake of Radio 4 ?

You obviously missed an episode of The Simpsons.

Elmo knows where you live!

Are there radio licenses, too?

And there's something to be said for disparate funding for disparate social programs. It doesn't always make sense or work, but TV seems an appropriate place. If those folks don't like the TV tax, they can just get rid of their TVs and not pay it. If they're watching it, then they need to be paying. Seems simple enough to me. It's kinda like HBO or Showtime or whatever in the US. Of course, it's not required that you get a premium cable channel in the US to see the rest....

And the output of TV doesn't really benefit anyone except those who watch TV, so it's not a broad social program whose lack of funding would affect those who aren't interested.

Are there radio licenses, too?

No, but the money from the TV licence goes to pay for the BBC radio channels as well. I suspect there were radio reception licences in the early days though.

It is much, MUCH better than the alternative.. commercials every 5 minutes or less.

Cheers

Your tax dollars (assuming you pay federal taxes) fund PBS whether you own a TV or not.

federal taxes) fund PBS

Though that particular subsidy (among countless thousands in the budget) appears to be on its way out.

Oh, i in no way mean that i wouldn't support PBS unless forced... About all i ever watch is PBS actually. I'm more than happy to pay a large chunk to keep them going! I personally think the TV tax in the UK to fund the BBS is a good thing... though the way it's enforced seems a bit draconian, not that i have a better solution. I'm all for public funding of the arts.

Funding the BBS? I didn't know this BBS was that important...

A colour license for a year is £116 whilst a B&W license is roughly £40. So if you think of it in terms of how much you pay a week it's not much.

A colour license for a year is £116 whilst a B&W license is roughly £40

Which all adds up to £2.8bn a year (it gets another £1.1bn from commercial operations), I guess TV is an expensive business...

...in fact output on BBC1 costs £160,000 an hour to produce, on average...

...also discovered while googling that the BBC website serves 1.2 billion page impressions a month !

http://www.bbc.co.uk/info/report2003/pdf/facts.pdf

Wow. £2.8 billion is a fair bit! I suppose it does have a lot of stuff to fund with the licensing fee. Who maintains the transmitters dotted around the country? Is it part of the BBC?

The BBC don't run the transmitters, I think that is NTL and Crown Castle.

I seem to remember that the BBC pay about £100m a years for transmission costs.

Funding the BBS? I didn't know this BBS was that important

PBS... BBS... BBC... PBC... whateva. =]

In reply to:

---

I seem to remember that the BBC pay about £100m a years for transmission costs.

---

That figure could rise quite steeply as CC and the Beeb reach the end of their 'honeymoon' period.
I always find it amusing that whenever I go to a transmission station I'm always greeted by ex-bbc employees. A lot of the notices dotted about the place have still got BBC Transmitter Department written on them!