Apparatus and method for detecting intrusion and non-intrusion events

摘要

An apparatus (10) and method are provided for detecting an intrusion into a predetermined area. The apparatus (10) includes a transmitter (28) for transmitting a signal within the predetermined area. A first receiver (30) is oriented toward a first location within the predetermined area and receives reflected return signals of the transmitted signal. A second receiver (32) is oriented toward a second location within the predetermined area and receives reflected return signals of the transmitted signal. The second location is different from the first location. A controller (42) determines whether reflected return signals received by the first and the second receivers (30 and 32) indicate an intrusion or a non-intrusion event. The controller (42) provides an alarm signal for an alarm (44) when only one of the reflected return signals received by the first and the second receivers (30 and 32) indicates an intrusion.