There was another theory (spread by the media and by the half-denying-half-encouraging bbc) that the vans can detect iPlayer usage across WiFi by looking at the level of network traffic, and then to a range of IP addresses in an area intentionally changing the amount of data the app received up/down to see if network activity changed correspondingly.

https://www.express.co.uk/life-style/science-technology/6976...

It’s really all a big scare tactic though. The best way to detect iPlayer being used wrongly will be to see who registers for an account with an identifiable email address.

You say simply, but I think that's much more difficult than just detecting the presence of em noise conforming to a broadcast standard.

Anyone that's put an AM radio next to a CRT TV knows it emits em noise.

The CRT itself is, to over simplify, a high voltage capacitor. It's one of the most popular devices used to power hobbyist Tesla coils...

I don't know why everyone seems to think that just because TVs were "receive-only" devices, that they wouldn't emit any sort of easily detectable signal.

Also, when this enforcement began, broadcast was the only source of TV content, so the presence of a TV was generally proof of watching broadcasts. There wasn't really any need to prove the TV was tuned to any particular content.

Now, whether it is a practical, effective method of enforcement that was actually used is another matter.

Maybe poor phrasing on my part, but that's the prevalent theory I've seen for how they do it today. Various other methods of EM leakage might have worked in the past (unproven as far as I know), but modern televisions are so much better built that visible light leakage is believed to be the only effective detection method.

Yeah, I wouldn't expect it to work on flatscreens, since they don't have the high voltage components wrt the CRT.

That said- it doesn't really have to do with being built better, just completely different.

You're thinking too much like an engineer

Here's my TV detection method: look at their windows and see if there's a light flickering pattern that looks like a TV (if behind curtains) or maybe you can see the TV

'TV Light Simulators' are actually a thing:

https://duckduckgo.com/?t=ffab&q=tv+light+simulator&atb=v172...

Your point?

If you're trying to avoid being suspected of having a tv, that sounds as smart as trying to rob a gun store with a fake weapon

Sure, but that doesn't require a van full of equipment. (If we're talking about historically.)

Looking for light would also only work until people found out about it, and violators covered their windows.