伪随机码超声扩频测距系统设计与算法

针对单脉冲回波方式的超声测距方法存在的缺陷,借鉴雷达中的脉冲压缩技术,介绍了基于伪随机二进制序列(m序列)的超声扩频测距实现方法.伪随机码与超声载波采用ASK(幅移键控)调制方式,介绍了伪随机码超声扩频测距硬件方案和超声测距时延估计模型.针对超声换能器带宽特性和单脉冲回波特点,分析了m序列参数设计方法.提出了一种基于FFT的伪随机码包络相关快速时延估计算法,该算法将信号解调与匹配相关融合,大大降低了运算量.实验表明,本文介绍的伪码超声扩频测距硬件方案和快速算法可在便携式超声测距系统中实现,并可在多基站超声定位系统中推广使用.

Algorithm and Design for Pseudo-Random Sequence Ultrasonic Spread Spectrum Distance Measurement System

Aiming at the deficiencies of single echo ultrasonic distance measurement and referring to the pulse compression technology in radar,the realization method for ultrasonic spread spectrum distance measurement based on PRBS(m Sequence) is introduced.The author proposed the hardware circuit scheme and TDE(Time Delay Estimation) model for the system with the PRBS and ultrasonic carrier adopting ASK modulation mode.The m sequence parameter choice method is analyzed according to the bandwidth of ultrasonic transducer and the specialty of single echo.A fast TDE algorithm of the pseudo-random code envelope correlation based on FFT is presented,which combines the signal demodulation with the match correlation to decrease the operation quantity greatly.Experiments show that the hardware scheme and the fast algorithm can be realized easily in the portable ultrasonic distance measurement systems and can be spread to the multiple base-stations ultrasonic location systems.