Patent ID: 7760130

Claim:
A system for presence detection comprising: a first pulse generator producing a first pulse sequence having a first pulse repetition frequency; a second pulse generator enabled by the first pulse sequence to produce a second pulse sequence having a second pulse repetition frequency higher than the first pulse repetition frequency; a clocked circuit enabled by the second pulse sequence to generate a sequence of transmit enable pulses and a sequence of receive enable pulses, the transmit enable pulses having a first pulse length defined by a first number of pulses in the second pulse sequence and the receive enable pulses having a second pulse length defined by a second number of pulses in the second pulse sequence; a transmitter receiving the transmit enable pulses and actuated thereby to enter an active transmit state wherein the transmitter transmits microwave radiation; and a receiver actuated by the receive enable pulses to enter an active receive mode wherein the receiver detects the microwave radiation within transmitted by the transmitter, the receiver operable to determine whether an object is present in a detection volume based on the microwave radiation being received.