Optimized self-matching chaotic pulse position modulation excitation sequences for non-crosstalk ultrasonic ranging system

摘要

Chaotic Pulse Position Modulation (CPPM) excitation sequences have been used as transmitted signal to help eliminate crosstalk between multichannel ultrasonic transducers.The CPPM excitation sequences have good echo correlation characteristics,but the spectra of CPPM sequences are not totally matched to the ultrasonic ranging system.To make full use of the bandwidth resources of the ultrasonic ranging system,the self-matching CPPM excitation sequences are proposed to trigger ultrasonic transducers.To get the best echo correlation characteristics,a genetic algorithm is adopted to optimize the self-matching CPPM excitation sequences.The proposed methods are illustrated by an ultrasonic ranging system consisting of two-channel Polaroid 600 series electrostatic transducers.