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Research of Ultrasonic Distance Measurement System Based on Pseudo Random Digital Correlation

An ultrasonic distance measuring system is designed by using MC9S12DG128 microcomputer in this paper. To improve the measuring distance and accuracy, the ultrasonic signal can be modulated with pseudo random binary sequence, and time of flight (TOF) can be determined by calculating the cross-correlation function of the transmission signal and its echo signal. What’s more, the two-step correlation method is adopted in order to reduce the computational complexity. The experiments show that absolute error of the measuring equipment is less than 5 millimeter within the range of 1-5 meter.