A high accuracy ultrasound distance measurement system using binary frequency shift-keyed signal and phase detection

A highly accurate binary frequency shift-keyed ultrasonic distance measurement system for use in air
is described. This paper presents an efficient algorithm which combines both the time-of-flight method
and the phase-shift method. The method used will allow a larger range measurement than the phaseshift
method and also result in higher accuracy compared with time-of-flight method. The simulation in
air uses BFSK with the frequencies of 40 and 40.7 KHz. The system will give a resolution of
0.0231mm/° at different temperature and humidity. The main advantages of this system are high
resolution, low cost narrow bandwidth requirement and ease of implementation.