Object detection apparatus

Abstract

The transmission of a detection wave and the reception of a reflected wave are periodically repeated every transmission period. One received signal is compared with another received signal at a similar corresponding comparison periods in different transmission periods of a receiving time of the reflected wave. Switching between the comparison periods is performed each time the transmission period is updated. A waveform of a received signal in a block A0 corresponding to a reflected wave of an ultrasonic signal transmitted in a first transmission period is stored. The absolute values of differences between the waveform of a received signal in a block A1 corresponding to a reflected wave of an ultrasonic signal transmitted in a second transmission period and the stored waveform of the received signal in the block A0 are accumulated. The waveform of a received signal in a block B1 is stored. The absolute values of differences between the waveform of a received signal in a block B2 corresponding to a reflected wave of an ultrasonic signal transmitted in a third transmission period and the stored waveform of the received signal in the block B1 are accumulated. Similar processing is performed in each block and a final accumulated value is set as the amount of change.

Dependencies are inferred from the claim text.