【摘要】 采用数字相关的方法确定超声波测距中的渡越时间。借助于一个经过适当选择的伪随机序列信号作为超声波的发射信号,可以通过数字相关方法求出发射序列和接收序列的相位差,即渡越时间。本文在计算自相关函数时放弃了快速傅立叶变换(FFT)算法,省去了乘法运算,取而代之的是只用异或和加法的并行数字相关技术,它显著地减少了数据处理时间和FPGA资源。系统以Altera公司的quartusⅡ为开发平台,经逻辑综合、布局布线后,适配到FPGA芯片中,给出了仿真结果。更多还原

【Abstract】 Digital correlation approach is used to find the time of flight(tof) in ultrasonic distance measurement. With the help of an adequately chosen Pseudo random Number (PN) as transmitting signal of the ultrasonic sensor, the time of flight can be got by using digital correlation approach to fine the phase difference between transmitting sequence and receiving sequence. The correlation function is computed by using xor and add operation taking place of FFT algorithm using multiplication. This method shortens the processing time and FPGA resource.The system design is based on Aletra’s quartusⅡsoftware, and described by VHDL language and be fitted to FPGA chip after logic synthesizing and placement routing. The timing simulation result in placement and routing is also presented.更多还原