Sometimes called "pulse radar
" or "RF hold
". Refers to a feature of some modern police radar
speed measuring devices to sit in a warmed-up state without emitting any radar pulses. When a car
comes into range, the police officer
activates the radar and a speed
measurement is taken almost instantaneously.
Instant-on radar is infuriating for speeders, because radar detectors cannot detect the radar gun until it is actually emitting radar waves. Luckily, the pulses caused by instant-on radar being used on traffic ahead of you can bounce back to your detector in time to give you ample warning; however, if you're the only car on the road, you're out of luck.