Crosstalk Elimination Method Based on Chaotic Binary Amplitude Shift Keying

The important indicators of multichannel ultrasonic ranging system are correlation characteristics and energy efficiency. The excitation sequences with good correlation characteristics can help avoid crosstalk among multi- channel ultrasonic sensors. High energy efficiency can enhance measurement range. This paper proposes a crosstalk elimination method by using the optimal binary excitation sequences modulated with chaotic codes, which include chaot- ic binary amplitude shift keying (c-BASK), chaotic binary phase shift keying (c- BPSK) and chaotic binary frequency shift keying (c-BFSK). To obtain the both best correlation characteristics and energy efficiency, the Non-dominated Sort- ing Genetic Algorithm-II (NSGA-II) is applied to optimize the chaotic binary excitation sequences. Real experiments have been conducted using an ultrason- ic ranging system that consists of eight-channel SensComp 600 series instru- ment-grade electrostatic sensors excited with chaotic binary modulation se- quences. The experimental results show that the c-BFSK outperforms the c- BASK and c-BPSK in terms of the correlation characteristics and energy effi- ciency. With 2 ms c-BFSK excitation sequences, the longest measurable dis- tance was 720 cm (i.e., increased 11% and 27% with c-BPSK and c-BASK, re- spectively) with maximal relative error 2.4%.