A novel ultrasonic ranging system based on the self-correlation of pseudo-random sequence

A novel ultrasonic ranging system based on the self-correlation of pseudo-random sequence is designed in this paper. Modular design is applied in this ultrasonic ranging system, which can measure the ultrasonic propagation velocity and transit time accurately, and then calculates the obstacle´s distance. Low power consumption and high performance TMS320VC5509A DSP is used as the ultrasonic ranging system´s signal processor. In order to improve the correlation calculation´s real-time performance, correlation judgment algorithm based on FFT is adopted. The ultrasonic receiving circuit is improved by absolute-value circuit instead of the traditional detection circuit, which effectively demodulates the pseudo-random sequences from the received ultrasonic waves. An error correction algorithm for this ultrasonic ranging system is proposed. The ultrasonic ranging system´s performance test was conducted under the interference existed environment. The experimental results demonstrate that the ultrasonic ranging system has good anti-interference performance and its ranging errors are within 1.8%.