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-   -   TV Detector Vans (https://www.vintage-radio.net/forum/showthread.php?t=72483)

Junk Box Nick 1st Aug 2011 3:01 pm

TV Detector Vans
 
I vaguely remember seeing photographs of TV detector vans back in the day of 405 line telly and if I recall correctly they were Commer vans - the ones with sliding front doors - with a couple of long conical horn type constructions bolted onto the roof.

There's a lot of myth surrounding them. Did anyone ever see one or even work in one?

ms660 1st Aug 2011 3:12 pm

Re: TV Detector Vans
 
Never worked one but remember them.
Do they still have them today?
I was hounded recently by the licensing authorities, I think they need some decent address/merge software in their IT systems!

Cheers.

newlite4 1st Aug 2011 3:17 pm

Re: TV Detector Vans
 
See here:

http://www.autoblog.com/2008/06/09/a...detector-vans/

Neil

XTC 1st Aug 2011 3:18 pm

Re: TV Detector Vans
 
Only one, and it was in the early 80s when they were doing a licence purge in the area. it looked really ancient.

I read in a newspaper that these days they don't have them because the gear has grown smaller with the rest of electronics and the inspectors have hand held TV detectors.

They may have just about worked, but I'm sure most enforcement is down to paper work, psychology and people confessing. I'm not sure that they ever successfully prosecuted anyone on the basis of detector van evidence alone.

Pete.

Sideband 1st Aug 2011 3:32 pm

Re: TV Detector Vans
 
Did they ever actually 'detect' anything? Was it all just a scare factor and in fact the vans contained nothing that actually did anything? I know it was possible to detect timebase noise but it's doubtfull if you could actually determine which channel someone was tuned to.


SB

XTC 1st Aug 2011 3:36 pm

Re: TV Detector Vans
 
Mainly kidology I'd have thought.

Pete.

Station X 1st Aug 2011 3:37 pm

Re: TV Detector Vans
 
The journal of "The Institute Of Post Office Electrical Engineers" (IPOEE) certainly featured articles describing the equipment in the vans and how it worked. A portable detector was used in blocks of flats. The Post Office Gazette also ran adverts for staff to do a stint manning the vans. Applicants had to have a driving licence, be able to demonstrate the equipment to the media and be prepared to give evidence in court. The vans were regularly parked in local Telephone Engineering Centres (TECs) during the day and ventured out in the evenings at peak viewing times.

It could have been an elaborate hoax, but I doubt it.

Skywave 1st Aug 2011 3:41 pm

Re: TV Detector Vans
 
Quote, Sideband: "I know it was possible to detect timebase noise but it's doubtfull if you could actually determine which channel someone was tuned to".

I'm not so sure about that, SB. :-/

The local osc. will almost certainly radiate some of its signal from the aerial - albeit at a significantly reduced level, but enough for a sensitive receiver to find it and then do the necessary D.F.
In a parallel vein, at about the period in question, when I used my Eddystone 888A receiver on 10 metres with a 110' 'longwire', it used to completely block out TV reception downstairs - much to the annoyance of my parents - and the TV received field strength was substantial - you could see the TV TX mast on the nearby hill from the lounge window!

Morever, the technique of 'electronics evesdropping' (and its prevention) has been used for many years by various Government Security Agencies: look up 'Tempest' on the 'Net: same principles are involved.

Al.

M0ALK Richard 1st Aug 2011 4:02 pm

Re: TV Detector Vans
 
I was told that the detector van would turn up at an estate somewhere and invite all the kiddies inside and show them how it worked. The kiddies would go home and tell their parents and the next day there would be a queue outside the post office of people wanting to buy a TV licence.

G8HQP Dave 1st Aug 2011 4:13 pm

Re: TV Detector Vans
 
There was a long thread on here about TV detector vans a year or so ago. It was inconclusive, but which I mean people were not convinced for or against the idea that the vans actually worked as described. Not much point in repeating it.

mickjjo 1st Aug 2011 4:18 pm

Re: TV Detector Vans
 
See:-

http://www.britishtelephones.com/veh...htvans/023.htm

There was a discussion about this in this thread last year from post # 64 :-

https://www.vintage-radio.net/forum/...tor+van&page=2

Some were real but a lot were fakes.

Regards, Mick.

julie_m 1st Aug 2011 4:38 pm

Re: TV Detector Vans
 
Of course, if you knew what IF the detector vans used (I'm presuming, not unreasonably, that they were superhets) you could, with a sensitive enough receiver, build a TV detector van detector; which would pick up the detector van's local oscillator and automatically switch off the TV as soon as a TV detector van was detected .....

Having a free choice of IF, you'd not be quite so vulnerable to a TV detector van detector detector!

Why wasn't a smartcard reader mandated for all digital receivers, whether combined or separate, from the outset? Then the BBC could have just issued viewing cards for their programmes, and had automatic licence fee enforcement with no need for heavy-handed tactics.

HamishBoxer 1st Aug 2011 5:16 pm

Re: TV Detector Vans
 
When colour arrived,it was the 4.43Mhz Oscillator that was detected and of course it cost much more for the licence.

David

Skywave 1st Aug 2011 5:19 pm

Re: TV Detector Vans
 
Indeed, AJS: ECM (electronic counter-measures) & ECCM (electronic counter-counter measures) are at the core of your suggestions, re-your paras. 1 and 2. And in certain, well-guarded corridors of power, the associated technology & its implementations are kept well under wraps. I can say no more.

Al. / Skywave.

Skywave 1st Aug 2011 5:21 pm

Re: TV Detector Vans
 
Quote:

Originally Posted by HamishBoxer (Post 453976)
When colour arrived, it was the 4.43MHz oscillator that was detected.

In which case, detecting the local oscillator radiation - and thus deducing what channel the set was tuned to - would also have been possible.

Al.

ms660 1st Aug 2011 5:39 pm

Re: TV Detector Vans
 
Is anyone in possesion or restoring any of the tv detector stuff?
I guess TV detection will be a thing of the past soon.

Cheers

kalee20 1st Aug 2011 5:48 pm

Re: TV Detector Vans
 
It would be great for a Forum member to find and restore an old detector van! Not much chance though, I bet...

Quote:

Originally Posted by Skywave (Post 453979)
In which case, detecting the local oscillator radiation - and thus deducing what channel the set was tuned to - would also have been possible.

How? I thought that by the time colour TV arrived, both the BBC and ITV timebases and colour subcarriers were so accurately generated that you couldn't distinguish between them

Boom 1st Aug 2011 5:54 pm

Re: TV Detector Vans
 
Quote:

Originally Posted by Sideband (Post 453944)
I know it was possible to detect timebase noise but it's doubtfull if you could actually determine which channel someone was tuned to.

Wouldn't the identification offset used by stations show up on the line timebase? It is this which causes two seperate but locked pictures to be seen if received together (??)

HamishBoxer 1st Aug 2011 5:57 pm

Re: TV Detector Vans
 
The 4.43 was picked up to determine that there was a set running and if the location didnt have a licence then i guess there was a loud knock on the door.

David

mickjjo 1st Aug 2011 6:06 pm

Re: TV Detector Vans
 
Quote:

Originally Posted by kalee20 (Post 453989)
It would be great for a Forum member to find and restore an old detector van!

The only known Commer TV detector van to survive has been restored:-

http://www.flickr.com/photos/29485695@N02/5666139441/

Took about 6 years:-

http://66.129.69.181/forum/topic.asp...8&whichpage=20

Regards, Mick.


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