Method and system for presence detection
View Patent ↗A method for presence detection using a microwave transmitter and a microwave receiver, the method including generating a sequence of clock pulses by means of a pulse generator, feeding the clock pulses to a clocked circuit arranged to generate a sequence of first pulses of a first pulse length and a sequence of second pulses of a second pulse length, each one of the first and second pulse lengths being related to a predetermined number of the clock pulses, periodically actuating the microwave transmitter by means of the sequence of first pulses, periodically actuating the microwave receiver by means of the sequence of second pulses; and determining whether an object is present in the detection volume based on microwave radiation being received by the microwave receiver. A system for such presence detection is also disclosed.
1. 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.
2. The system according to claim 1 further comprising a microcontroller controlling the clocked circuit by determining a relation between the number of clock pulses fed to the clocked circuit and the first and second pulse lengths.