| Radar Detectors illegal? In some countries, using a radar detector is declared illegal and may be subject of fines or seizure of the device. Because the detectors are built around a superheterodyne receiver, and its local oscillator radiates a little, it is possible to build a radar detector detector detecting such emissions (usually the frequency of the radar they are detecting, plus about 10 MHz) - some police radar guns are equipped with it. But electronic warfare cuts both ways, and the detector detectors use a superhet receiver too, so some radar detectors are equipped with a radar detector detector detector circuit, which shuts down the main radar receiver when the detector detector's signal is sensed, thus preventing being sensed by the police equipment. This problem is related to technical surveillance countermeasures and ELINT. |