Sensors Network for Ultrasonic Ranging System

The spectrum matching and correlation characteristic are both important in the multiple-user ultrasonic ranging system. As people know, an ultrasonic ranging system, which has a bell-shaped magnitude spectrum, acts like a band-pass filter. If the spectrum of the excitation signal does not match that of the ultrasonic ranging system, some of energy cannot be transmitted by the ultrasonic system. In other words, it does not make full use of the bandwidth of the ultrasonic ranging system. The good correlation characteristics can eliminate cross-talk among multichannel ultrasonic sensors firing simultaneously. To the authors’ knowledge, not many researchers considered how to make the spectrum of the excitation sequence match to that of the ultrasonic ranging system as well as improve the correlation characteristics. In this paper, the chaotic frequency modulation (CFM) excitation sequences are proposed for multiple-user ultrasonic ranging system. To obtain the excitation sequences which are spectrally matched to the ultrasonic ranging system as well as have the best correlation characteristic, the NSGA-II is applied to optimize the CFM excitation sequences.