Patent ID: 6677887
Filing Date: 2004-01-13
Classification: G01S

Abstract:
A method of detecting the location and direction of movement of an intruder in a detection zone, said method comprising the following steps:a) alternately transmitting first and second frequency signals to the terminus of the detection zone; b) detecting Doppler response signals from an intruder in the detection zone to provide first and second response signals; c) sampling the first and second responses during a sampling period and generating corresponding first and second digital signal pairings; d) classifying said digital signal pairing according to the phase of the respective Doppler response signals into even phase ZE and odd phase ZO signals; e) determining the range to the intruder from an accumulation of ZE and ZO signals. f) determining the sum of the ZE and ZO signals to provide a response amplitude signal, and g) comparing said response amplitude signal to a range dependent threshold.