Fractional fourier transform for ultrasonic ranging device

Ultrasonic ranging device send out ultrasonic pulse for the measurement, the reflected acoustic wave is received by the device and changed into electrical signal by piezoelectric sensor; the distance is calculated according to the time different of sending and receiving. But there is noise in the echo acoustic wave that will affect the quality of the received signal, which will make the reading wrong or instability. This study proposes a new filtering method, first the echo signal is processed by fractional Fourier transform, then most of the noise is filtered out by the band pass filter, finally the original signal is restored by inverse fractional Fourier transform, making echo quality better. This method integrates the information of the signal in time domain and frequency domain information, improves the signal-to-noise ratio compared with the traditional filtering methods, make signal noise separation more effectively.