Instant On (I/O) occurs when the operator manually switches his RADAR unit between on and off (emitting a detectable signal and not emitting a detectable signal). Traffic officers often do this for a number of reasons. Likely the most prominent is to catch radar detector users. Imagine driving down a road and your radar detector suddenly lights up full strength. This is because the operator has activated his RADAR instantly. Two other goals of instant on are to cut the amount of microwaves exposed to the user and eliminate the loud doppler audio when not desired/needed.