I saw the Cat Detector van!

Driving down my street.

I’ve never seen so many bleedin’ aerials (I counted at least 6, although the photo doesn’t show them all).

Where are the cats? I want cats.



Did Eric escape detection?

its a van that they use in the uk to make sure your not avoiding the infamous tv tax by tracing the cable /antenna signals cause the BBC needs its loot for all the gorgeous nature shows sir Attenborough makes ……. (and other than dr who there the only British thing on BBC America)

I’ve never understood how they can detect that a tv is receiving.

Signals go through the air, bounce off objects, go through walls. Some even escape into space. How can they tell a signal wandered into your tv’s rabbit ears?

Do tv’s in the UK have a special chip that transmits a signal authorities can detect? A transmitters location can easily be tracked.

I know they’ve been detecting unlicensed tv’s for decades. Whatever they’re doing works.

Looney detector van, you mean.

Whatever they are doing seems to be a well kept secret. Only a few details here.

This sounds like the technobabble they say on Star Trek.

It’s people like you what cause unrest.

Now, LOOK!

Many (most?) receivers are super heterodyne (https://en.wikipedia.org/wiki/Superheterodyne_receiver). If you are tuned to (analog) channel 27 (picture carrier 549.25 MHz) it is mixed with 595* MHz to produce a 454.75 MHZ
(For a different channel it is mixed with freq + 45.75 MHz) then the 45.75 MHz signal is amplified.
I’m not sure if they go for the mixer frequency or the intermediate frequency, in any case your TV does produce RF that can be detected

Digital TV is a bit different, but I believe you will still get RF out of it


  • It could be carrier freq - 45,75


That’s the way it was spelled on the van!

You’re very observant.

I hadn’t considered that possibility. I agree it could be the oscillator in the circuit. Or a stage in the IF circuit.

That’s just a fancy way of saying they saw (and probably recorded for evidence) a tell-tale variable glow emanating from their window. Doesn’t sound very high tech.

You know how it works? They drive the vans down the street to scare people into paying (actually it’s been years since I’ve seen one).

To actually find TVs, they look through windows, send letters to anyone who hasn’t paid for a license, and occasionally send people round to check. The only way anyone gets fined is 'cos an enforcement guy actually sees a TV. All else is theatre.

I’ve known a few people get caught because the TV was visible from the doorway, or in a shared house because someone didn’t realise their housemate had one and let the inspector in (they don’t show up with a warrant). I’ve also known people who just hid it in a cupboard and did not get caught or fined.

They showed up at my old house, I just said I didn’t have a TV, which was true, but I did not give them permission to come and search. They went away and didn’t come back.

Incidentally, technically, until the internet made it more complicated to define, you needed a license if you had equipment capable of receiving a signal, it wasn’t necessary to have it in operation.

NHK in Japan has people going around knocking on doors. I never paid because I didn’t own a TV. Since I’m a foreigner they gave up really quickly.

For years, I was waiting for my brother in Utah to show up and claim the TV I had bought for him. . . It was rather kind of him to allow me to use it in the meantime.

Sounds like they’re describing what is commonly called a “camera”.