Abstract: In an intrusion detection device of the embodiment, a determining unit allows a transmission unit to stop transmitting ultrasonic waves until a level of a Doppler signal exceeds a predetermined threshold (threshold for detecting destruction of a window glass), and allows the transmission unit to transmit the ultrasonic waves when the level of the Doppler signal exceeds said threshold. Therefore, if the destruction of the window glass is not detected, it is possible to reduce power consumption through allowing the transmission unit to stop the transmission. Further, because processing for detecting intrusion is performed after the destruction of the window glass has been detected, it is possible to reduce erroneous detection of an intruder resulting from a movement of an object (e.g., falling of papers, a sunshade, or the like that is leaned against the interior wall) other than a human.

Abstract: In an intrusion detection device of the embodiment, a determining unit allows a transmission unit to stop transmitting ultrasonic waves until a level of a Doppler signal exceeds a predetermined threshold (threshold for detecting destruction of a window glass), and allows the transmission unit to transmit the ultrasonic waves when the level of the Doppler signal exceeds said threshold. Therefore, if the destruction of the window glass is not detected, it is possible to reduce power consumption through allowing the transmission unit to stop the transmission. Further, because processing for detecting intrusion is performed after the destruction of the window glass has been detected, it is possible to reduce erroneous detection of an intruder resulting from a movement of an object (e.g., falling of papers, a sunshade, or the like that is leaned against the interior wall) other than a human.