DEVICE FOR DETECTING MOVING DIRECTION OF MOVING OBJECT

摘要

PURPOSE:To detect the parting and approach of a moving body with high accuracy without using a filter having a sharp cutoff characteristic even at a low speed by processing dividedly two sets of the beat output based on the ultrasonic reception signal reflected from the moving object with LPFs having different bands. CONSTITUTION:The ultrasonic signal reflected from the moving object and received by a receiver 4b is multiplied by the frequency signal lower by a specified value than the oscillation frequency of the transmitter 4a of the 1st inside oscillator 7a and the frequency signal higher than the output of the 2nd inside oscillator 7b and lower than the frequency of the received signal by a multiplier circuit 8 of a beat circuit means 6 and is made into two sets of the beat signals sharing the received Doppler signal. These beat signals are outputted through the 2nd LPF9b and the 1st LPF9a having respectively different bands and a gate circuit 8d controlled according to the signal transmission. The parting of the moving object is thus detected with high accuracy without using the filter having the sharp cutoff characteristic even if the moving speed is low as the Doppler frequency is dividedly processed. The approach of the moving object is similarly detected by the beat from the frequency signal larger than the oscillation frequency.