How do television detectors work ?

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Discussion Overview

The discussion revolves around the functioning of television detectors used by licensing vans, specifically how they detect unauthorized TV signal reception. The scope includes technical explanations, conceptual clarifications, and some historical context regarding signal detection methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether TV detectors work by measuring the power loss of broadcast signals as they are received by televisions.
  • Another participant notes that in the UK, a license is required for broadcast receiving equipment, contrasting it with the U.S. where broadcast television is free to the receiver.
  • Concerns are raised about the nature of signal detection, with a participant mentioning that news vans use different frequencies (microwave) that are not compatible with standard TV tuners.
  • A participant suggests that the detection method involves identifying intermediate frequencies produced by the television or converter, which could indicate what channel is being watched.
  • There is speculation about whether computers with TV cards can be detected by these vans, questioning if the computer casing provides sufficient shielding from detection signals.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of detection and the implications of licensing requirements. There is no consensus on how exactly the detection works or the specifics of signal reception and licensing across regions.

Contextual Notes

Some participants reference historical methods of signal detection, suggesting that the techniques may have evolved from earlier practices used during WWII. There are also assumptions about the nature of broadcast signals and the technology used in detection that remain unverified.

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How is it possible that TV detector's work like the ones used by the TV licensing vans, is it by measuring the TV broadcast signals power loss ?
 
Engineering news on Phys.org
http://www.tv-l.co.uk/tvlic/penalties/detection_tvvans.html
http://www.sciencenet.org.uk/database/Technology/Original/t00033d.html

Isn't broadcast television free to the receiver in the U.K. as it is in the U.S.A.?
I've never heard of an unlicenced broadcast reception. (Satellite or cable sure, but broadcast?)
 
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Here in the UK you have to buy a license each year for the broadcast receiving equipment.A colour TV is more expensive than black and white TV, to top it all off we only get two advertising free channels, the other three have lots of adverts :(
 
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Was your original question about pirating the signal directly from a news van? They use different frequencies than your tv tuner. They're microwave. Thats why they have the long supports - they're highly directional.
 
Originally posted by russ_watters
Was your original question about pirating the signal directly from a news van? They use different frequencies than your tv tuner. They're microwave. Thats why they have the long supports - they're highly directional.

No. I thought that as the TV receives the broadcast signal and creates a picture out of it, this would result in the broadcasts signal strength being diminished (which could be detected). But I stand corrected.
 
Originally posted by username
Here in the UK you have to buy a license each year for the broadcast receiving equipment.A colour TV is more expensive than black and white TV, to top it all off we only get two advertising free channels, the other three have lots of adverts :(

I never knew that. Live-and-learn.
Is this representative of Europe in general? (You don't learn these things staying in hotels.)
 
i think he means

how can they tell if you're pirating programs. Well your converter or television set uses an intermediate frequency and the frequency converter circuit produces that frequency and the other difference frequency. And the van has a reciever which can detect the other difference frequency and tell what channel you are watching.


It's an old trick that was used for detecting radio recievers during WWII.
 
Does that mean that computers with a TV card can not be detected? Or does the TV card itself have the intermediate 39MHz frequency as well? If you keep your computer's casing closed shouldn't it shield it from signals from the detector van?
 

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