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"...it was thought that they operated by detecting electromagnetic radiation given off by a TV. The most common suggested method was the detection of a signal f
by tlb 7y ago
"...it was thought that they operated by detecting electromagnetic radiation given off by a TV. The most common suggested method was the detection of a signal from the TV's local oscillator."
This seems extremely tricky to do, and it wouldn't be very directional. Why not just look for the flickering light pattern from a TV coming out people's windows? You could correlate the brightness changes with the broadcast signals on each channel to know what people are watching.
- woodrowbarlow 7y agothat's exactly how it works, apparently: "the optical detector in the detector van uses a large lens to collect that light and focus it on to an especially sensitive device, which converts fluctuating light signals into electrical signals, which can be electronically analysed"