Velocity Measurement by Microcomputer Using Supersonic Wave for Physics Education

In this paper, we propose a velocity measurement method using period of supersonic wave for physics education. We separate a transmitter and a receiver in this method. The transmitter is put on the movement body and transmits the supersonic wave of 40kHz continuously. The receiver converts the supersonic wave into a digital square wave. A microcomputer with two timer counters is used in this method. The timer counters count the square wave and the system clock. The period of supersonic wave is calculated by these values of counters and the velocity measurement of the movement body becomes possible by the Doppler effects. We examine the characteristic and the effectiveness of this method by fundamental experiment.