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Old 11-06-2013, 14:55
mrblank
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can someone clear this up once and for all.could they really track tvs or were they just a bluff to get people to buy tv licenses when they saw a van in their area
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Old 11-06-2013, 15:38
Nigel Goodwin
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can someone clear this up once and for all.could they really track tvs or were they just a bluff to get people to buy tv licenses when they saw a van in their area
Yes they could - but even back when they existed there were only ever a very small number of real ones, most were just dummy vans which scared people in to buying a licence.

Back in the mid 70's I was taken inside one, and shown how it all worked - basically a lot of expensive professional radio and electronics gear, and two VERY highly skilled and qualified engineers to use it.

They were able to pick out individual TV's in the workshop, and tell me which channels they were on - and they were completely right on every one.

But as far as I'm aware there haven't been any for a number of decades now - far too expensive, and not cost effective. Much cheaper to send guys round knocking on doors.
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Old 11-06-2013, 16:57
Tom2023
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All valves radiate radio frequency signals. So when an old fashioned TV was busy processing the TV signal it would be re-radiating it's own signal. If I was doing it I would try to detect the output of the TV's largest valve, the CRT.

It's quite a simple process to scan the spectrum and detect a signal then to use directional aerials to get a bearing. Of course you'd need at east three bearings to triangulate a position and even then it might not be too accurate.

It is claimed in various places on the internet that no detector van evidence was ever used in a UK court. But that's typical of the BBC, scaring people.
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Old 11-06-2013, 17:28
Monty_Hall
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It is claimed in various places on the internet that no detector van evidence was ever used in a UK court.
I think this was actually published by the BBC themselves after a prolonged barney with the ICO.

Looks like it was discussed here at the time: http://forums.digitalspy.co.uk/showthread.php?t=1480075
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Old 11-06-2013, 18:11
John146
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Yes they could - but even back when they existed there were only ever a very small number of real ones, most were just dummy vans which scared people in to buying a licence.

Back in the mid 70's I was taken inside one, and shown how it all worked - basically a lot of expensive professional radio and electronics gear, and two VERY highly skilled and qualified engineers to use it.

They were able to pick out individual TV's in the workshop, and tell me which channels they were on - and they were completely right on every one.

But as far as I'm aware there haven't been any for a number of decades now - far too expensive, and not cost effective. Much cheaper to send guys round knocking on doors.
Worked for BT and whilst I cannot remember the year(s) TV Detector Vans used to be parked overnight at the local exchange, very strange cone shaped aerial on the roof, and yes the engineer that went out with this vehicle was a very highly skilled engineer.
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Old 11-06-2013, 20:40
Nigel Goodwin
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Worked for BT and whilst I cannot remember the year(s) TV Detector Vans used to be parked overnight at the local exchange, very strange cone shaped aerial on the roof, and yes the engineer that went out with this vehicle was a very highly skilled engineer.
There were two engineers in the one I was shown round, both with electronics degrees of some kind - although I think they were also sometimes run by an engineer and a less qualified driver.
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Old 11-06-2013, 20:43
CM
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can someone clear this up once and for all.could they really track tvs or were they just a bluff to get people to buy tv licenses when they saw a van in their area
There's no such thing as detector vans.
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Old 11-06-2013, 20:43
Nigel Goodwin
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All valves radiate radio frequency signals. So when an old fashioned TV was busy processing the TV signal it would be re-radiating it's own signal. If I was doing it I would try to detect the output of the TV's largest valve, the CRT.
Sorry, but there's no accuracy anywhere in those sentences

Valves don't radiate particularly, and transistor sets were just as easily detected as valve ones.

Specific signals looked for were the tuner LO emissions (which told them which channel you were on), and the colour sub-carrier oscillator emissions (at 4.43361875 MHz) which proved that it was a colour set.
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Old 11-06-2013, 20:45
Nigel Goodwin
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There's no such thing as detector vans.
As I've always said - not THESE days

As far as I'm aware the last ones were old Commer vans?.
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Old 12-06-2013, 18:13
CM
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As I've always said - not THESE days

As far as I'm aware the last ones were old Commer vans?.
Thought it must have been a while since they were about.
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Old 12-06-2013, 18:29
bobcar
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But that's typical of the BBC, scaring people.
The only people that would be "scared" would be those watching without a licence so I'd say good to that.
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Old 13-06-2013, 01:01
Winston_1
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Worked for BT and whilst I cannot remember the year(s) TV Detector Vans used to be parked overnight at the local exchange, very strange cone shaped aerial on the roof, and yes the engineer that went out with this vehicle was a very highly skilled engineer.
The one I saw had 2 Wolesey colour king aerials on the roof mounted back to back so they were beaming in opposite directions. It was at the BBC TV Centre doing a test of some sort driving round and round the inner circle with a battery operated TV in the middle of the circle.
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Old 13-06-2013, 09:12
Nigel Goodwin
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The one I saw had 2 Wolesey colour king aerials on the roof mounted back to back so they were beaming in opposite directions. It was at the BBC TV Centre doing a test of some sort driving round and round the inner circle with a battery operated TV in the middle of the circle.
That sounds nothing like a detector van

More likely a test van of some purpose - perhaps used for doing coverage tests on new transmitters?.
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Old 13-06-2013, 11:16
Winston_1
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That sounds nothing like a detector van

More likely a test van of some purpose - perhaps used for doing coverage tests on new transmitters?.
It had the words "TV Detector Van" or similar on the side.
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Old 13-06-2013, 11:22
grps3
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detector vans do not exist
they have vans pretending to do detecting

they have a database of people who have licences and check on people who dont

i have no tv goodbye
closes door

exits thread
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Old 13-06-2013, 11:36
Winston_1
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detector vans do not exist
they have vans pretending to do detecting

they have a database of people who have licences and check on people who dont

i have no tv goodbye
closes door

exits thread
There may not be any now, but they certainly used to exist, and they were not pretending.
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Old 13-06-2013, 11:39
grps3
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There may not be any now, but they certainly used to exist, and they were not pretending.
could you explain the tech used to detect your tv?
can you show us bbc accounts where they detail research cost and training costs for detecting equipment/staff training etc

if anyone has been prosecuted , what evidence did the tv licencors produce in court aside from no tv licence and owns tv?

answer all these i might believe they exist
but since you wont be able to , they dont exist

also tvs/monitors are so shielded you prob couldn't detect them while in same room, never mind outside on street
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Old 13-06-2013, 11:46
grps3
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wrong thread lol
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Old 13-06-2013, 12:05
Nigel Goodwin
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It had the words "TV Detector Van" or similar on the side.
So did all the dummy vans
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Old 13-06-2013, 12:14
Nigel Goodwin
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could you explain the tech used to detect your tv?
Professional radios, spectrum analysers, oscilloscopes and aerial equipment etc. PLUS highly skill graduate operators. I've explained above what they actually detected.


can you show us bbc accounts where they detail research cost and training costs for detecting equipment/staff training etc
Why would they provide such details?, or even still have them after 30-40 years?.


if anyone has been prosecuted , what evidence did the tv licencors produce in court aside from no tv licence and owns tv?
As far as I'm aware there's never been a prosecution based solely on detector evidence - that wasn't their mode of operation.


answer all these i might believe they exist
but since you wont be able to , they dont exist
Far too long ago to be available now, assuming it ever was? - but as I said above, I've been inside one (and shown how it worked) back in the 70's. As far as I'm aware there haven't been any since the 70's and perhaps early 80's?.


also tvs/monitors are so shielded you prob couldn't detect them while in same room, never mind outside on street
Sorry, completely incorrect - and shows a lack of electronics knowledge. Shielding REDUCES leakage, not prevents it.

As I've said before, detector vans DID exist, but I don't believe they have done so for a considerable number of years. They were never cost effective, and simply knocking on doors is far more efficient (bearing in mind the detector van operators had to knock on the door anyway, if they detected a TV inside).
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Old 13-06-2013, 13:31
diablo
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also tvs/monitors are so shielded you prob couldn't detect them while in same room, never mind outside on street
Try using a medium wave transistor radio to pick up Radio 5 within 20 feet of a CRT TV.

With the TV turned off everything is fine, with it turned on then you'll need to angle it just right to hear anything but interference.
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Old 13-06-2013, 18:30
35321
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Here's a picture of a TV detector van in Ireland, outside RTE, picture probably dates from the 1960s:

http://www.2rn.ie//vintage-gallery/p...office-014.jpg


pt = Posts and Telegraphs
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Old 13-06-2013, 19:15
alan1302
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could you explain the tech used to detect your tv?
can you show us bbc accounts where they detail research cost and training costs for detecting equipment/staff training etc

if anyone has been prosecuted , what evidence did the tv licencors produce in court aside from no tv licence and owns tv?

answer all these i might believe they exist
but since you wont be able to , they dont exist

also tvs/monitors are so shielded you prob couldn't detect them while in same room, never mind outside on street
There must be a lot in life that you don't believe exist then
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Old 13-06-2013, 20:11
Tom2023
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Sorry, but there's no accuracy anywhere in those sentences

Valves don't radiate particularly, and transistor sets were just as easily detected as valve ones.

Specific signals looked for were the tuner LO emissions (which told them which channel you were on), and the colour sub-carrier oscillator emissions (at 4.43361875 MHz) which proved that it was a colour set.
It's possible to receive a radio signal from Australia on a 1/2 watt transmitter so detecting the radiation from a valve such as a hot CRT from 30 yards is a piece of cake.

I know because I did it many years ago whilst working for a sophisticated electronics organisation based in Cheltenham.
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Old 14-06-2013, 08:53
Nigel Goodwin
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It's possible to receive a radio signal from Australia on a 1/2 watt transmitter so detecting the radiation from a valve such as a hot CRT from 30 yards is a piece of cake.

I know because I did it many years ago whilst working for a sophisticated electronics organisation based in Cheltenham.
The 'radiation' isn't from the CRT, it's from the LOPT stage and scan coils, which is quite considerable.
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