伪随机序列超声测距系统及FPGA实现

Ultrasonic Range Measurement System Based on PRBS and FPGA Realized

超声测距系统中多路换能器同时工作存在的超声串扰会导致错误的测量和降低系统的工作效率。为了消除串扰,采用二进制频移键控调制(FSK)构造每个超声换能器的编码激励发射序列;结合超声回波信号模型,给出了超声回波信号的解调算法;设计了一种只用异或和加法的并行数字相关技术的回波序列识别和渡越时间捕获器,它能够抑制超声串扰和误码,显著减少数据处理时间和FPGA资源。FPGA仿真结果表明伪随机码(PRBS)可用于消除实时超声测距系统的串扰。

Ultrasonic crosstalk,which can seriously result in false distance measurement and decrease the work efficiency of ultrasonic range system, often occurs when multiple transducers working together. To eliminate the phenomenon of ultrasonic crosstalk,frequency-shift keying（ FSK）was used to construct the coded excitation triggering sequence for each ultrasonic transducer. Combining with the model of ultrasonic echo signal, a demodulating algorithm of the ultrasonic echo signal was presented ; A parallel digital correlation analysis that computed by using xor and add operation was used to construct the coded excitation and capture the time of flight was introduced, which can eliminate ultrasonic crosstalk and errs, and shorten the processing time and FPGA resource. The results of FPGA simulation demonstrate the pseudo-random binary sequence can be used to eliminate the erosstalk of the real-time ultrasonic ranging system.