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There's a few ways to detect radio receivers, some of them based on listening for incidentally radiated intermediate frequencies (which have to be a multiple of
by sbierwagen 6y ago
There's a few ways to detect radio receivers, some of them based on listening for incidentally radiated intermediate frequencies (which have to be a multiple of the received frequency) from the amplifier in the receiver: https://en.wikipedia.org/wiki/TV_detector_van https://en.wikipedia.org/wiki/TV_detector_van
It would be a heck of a trick to detect a GPS receiver that way, though. Probably be easier just to listen for the RF noise from the switching regulator in the power supply.
- londons_explore 6y ago> Probably be easier just to listen for the RF noise from the switching regulator in the power supply. Natural things give off very little RF... Pretty much anything electronic gives off far far more. It doesn't seem out of the realm of possibility for a military to use antenna arrays to try to track every nearby electronic device of any kind. Sure - identifying the device might be tricky, but you gain a lot of intel simply knowing where electronic devices are clustering and headed.
- ColanR 6y agoMost of the methods listed there were listening for the EM of the TV being on, not the reciever antenna. Technically, it sounds like they wouldn't be able to tell the difference between pirated TV and watching a movie on the VCR.
- LargoLasskhyfv 6y agoI think the reasoning for those TV-sniffing trucks at the time were not what you watch, but that you could watch at all, i.e. you had a device capable of watching TV and to pay your damn dues for that "privilege".