ULTRASONIC WAVE DISTANCE METER

摘要

PURPOSE:To increase he accuracy of distance measurement, by producing the attenuation signal due to the output of differentiation circuit together with the start of transmission of ultrasonic waves and enabling to correctly detect the reflection wave with the comparison between the received reflection wave level and attenuation signal level. CONSTITUTION:When the switch SW is applied for distance measurement, the pulse generation circuit 1 produces the pulse P1 and ultrasonic waves are transmitted from the speaker 6 with the first timer means 2. The pulse P1 operates the second timer means consisting of the monostable multivibrator having longer period than the time when the reflection wave from the objective 13 is incoming, and the signal of a given level is outputted. This output signal is converted into attenuation signal with differentiation at the differenctiation circuit 10. When the level V2 of reflection signal received at the microphone 8 is greater than the level V1 of attenuation signal, the comparator 11 produces the output and the time between this time and the pulse P1 is measured with the circuit 12.