基于FPGA的家用高精度超声波燃气表实现

Implementation of domestic high-precision ultrasonic gas meter based on FPGA

为满足家用超声波燃气表的要求,对当前超声波燃气表设计主流方案中存在的瓶颈问题进行研究,提出了基于FPGA的解决方案,分析验证了其可行性。超声波发射端利用基于FPGA的DDS技术产生经过伪随机序列编码的激励信号,接收端通过相关性运算精确计算出超声波渡越时间,进而利用频差法替代时差法计算气体流速,解决超声波燃气表在低流量时测量精度低、对不同成分气体适应性差的问题,利用FPGA实时监测超声波换能器的性能解决超声波燃气表难以长久使用的问题。

According to the requirements of domestic ultrasonic gas meter,Aiming at the bottleneck problems in current dominant design of ultrasonic gas meters,an FPGA-based solution is proposed and analyzed to verify the feasibility of this solution.The ultrasonic transmitter uses FPGA-based DDS technology to generate a pseudo-random sequence encoded excitation signal.The receiver accurately calculates the ultrasonic transit time through correlation calculation,and then the frequency difference method is used instead of the time difference method to calculate the gas flow rate,which solves the problems of low accuracy of the ultrasonic gas meter at low flow rates and poor adaptability to different gas components.At the same time,FPGA is used to monitor the performance of the ultrasonic transducer in real time to solve the problem that the ultrasonic gas meter is difficult to use for a long time.