Optimization of Matched Chaotic Frequency Modulation Excitation Sequences for Multichannel Simultaneously Triggered Ultrasonic Ranging System

摘要

The matched spectrum andcorrelation characteristics are both important to realize the multichannel ultrasonic sensors working together. The spectrum matching can make full use of the bandwidth of the ultrasonic ranging system, and the good correlation characteristic can eliminate crosstalk among multichannel ultrasonic sensors triggering simultaneously. Linear frequency modulation (LFM) excitation sequences have been used as transmission signals for ultrasonic sensors. Due to the narrow bandwidth of the ultrasonic ranging system, the number of available LFM excitation sequences is limited. The chaotic frequency modulation (CFM) excitation sequences, which can generate more available excitation signals, are proposed in this paper. The nondominated sorting genetic algorithm-ll is adopted to optimize both the spectrum and correlation characteristic of the CFM excitation sequences. After optimization, the CFM excitation sequences are spectrally matched to the ultrasonic ranging system as well as have best correlation characteristic. Real experiments have been implemented using an ultrasonic ranging system consisting of eight-channel SensComp 600 series electrostatic sensors excitedwith 2 ms CFM sequences. Experimental results show that spectra of the optimized CFM excitation sequences can match to the system and can work together without crosstalk.