> Analog TV sets tended to emit loudly at the local oscillator frequency. The UK used to drive around with "television detector" vans to find people who didn't

> Analog TV sets tended to emit loudly at the local oscillator frequency. The UK used to drive around with "television detector" vans to find people who didn't pay their TV tax, which funds the BBC. But tuners quieted down years ago, as they became tiny RF-tight sealed units. CRTs used to emit the picture on their screen well enough you could receive it over a nontrivial distance. This is called Van Eck phreaking. https://en.wikipedia.org/wiki/Van_Eck_phreaking https://en.wikipedia.org/wiki/Van_Eck_phreaking OTOH, being able to receive a signal and being able to nail down where it's coming from and who's broadcasting it are two very different things, and the location part is substantially harder. Using the Van Eck technique, or any other, to crack down on people not paying the BBC license fee would have cost more than the fee was worth. Psychological ploys with faked-up vans, however, are a lot cheaper, and can be fairly effective.