Patent ID: 7907082

Claim:
A system for presence control within a detection volume delimited by an inner radius and an outer radius from a center of said detection volume, said system comprising: a microwave transmitter for transmitting microwaves from said center of said detection volume; a microwave receiver for detecting microwave radiation reflected towards said center of said detection volume; a first pulse generator generating a sequence of first pulses triggering the microwave transmitter, each first pulse having a length establishing a transmit interval of said microwave transmitter; a second pulse generator receiving the sequence of first pulses and triggered by a trailing edge of each first pulse to generate a sequence of second pulses, each of the second pulses immediately following and non-concurrent with the respective preceding first pulse; and a third pulse generator receiving the sequence of second pulses and triggered by a trailing edge of each second pulse to generate a sequence of third pulses triggering the microwave receiver and having a length to establish a receive interval thereof, each third pulse immediately following and non-concurrent with the respective preceding second pulse, whereby each second pulse has a length defining a time period pause between each first pulse and each respective following third pulse, and wherein the second pulse length added to the third pulse length is equal to a transmitter off-time separating the first pulses.