基于FPGA的宽带ADCP流速校准系统  

Broadband ADCP Flow Rate Calibration System Based on FPGA

作　　者：陈奕基 郭世旭[1] 王萧博 焦君圣 赵鹏[1] CHEN Yiji;GUO Shixu;WANG Xiaobo;JIAO Junsheng;ZHAO Peng(Key Laboratory of In Situ Metrology Ministry of Education,China Jiliang University,Hangzhou,Zhejiang 310018,China;Zhejiang Institute of Metrology,Key Laboratory of Acoustics and Vibration Precision Measuring Technology for State Market Regulation,Hangzhou,Zhejiang 310063,China)

机构地区：[1]中国计量大学原位计量教育部重点实验室,浙江杭州310018 [2]浙江省计量科学研究院国家市场监管重点实验室(声学振动精密测量技术),浙江杭州3100632

出　　处：《计量学报》2024年第7期1064-1072,共9页Acta Metrologica Sinica

摘　　要：声学多普勒流速剖面仪(ADCP)可采用声学应答并发射模拟回波的方式开展流速校准,但其校准精度和校准流速下限受系统时钟精度影响,目前基于该方式的ADCP流速校准系统难以针对1 m/s以下小流速进行校准。提供了一种低成本、水池环境可实施的宽带ADCP流速校准系统方案,即基于FPGA设计一套宽带ADCP流速校准系统,采集ADCP发射声波信号并进行处理,再向ADCP发射携带水体流速信息的模拟回波信号,通过模拟流速值与实际输出值的比较,实现ADCP的流速校准。校准系统通过直接数字频率合成和锁相频率合成(DDS+PLL)的技术合成高精度时钟信号,时钟信号驱动信号采集与回放产生高精度模拟回波信号。最后,在小型消声水池内针对中心频率为300 kHz的宽带ADCP开展(0.2~1)m/s小流速校准实验,结果表明,该校准系统的测量不确定度达到(0.5%模拟流速值+0.005)m/s,验证了校准系统的可靠性。The ADCP(acoustic Doppler velocity profiler)can use the method of acoustic response and emission of simulated echoes to carry out flow calibration,but the calibration accuracy and the lower limit of calibration flow velocity are affected by the system clock precision.At present,the ADCP flow calibration system based on this method is difficult to calibrate the small flow velocity of less than 1 m/s.To provides a low-cost,water pool environment implementable broadband ADCP flow calibration system scheme,which is to design a broadband ADCP flow calibration system based on FPGA,collect and process the ADCP transmitted acoustic wave signal,and then transmit the simulated echo signal carrying water flow velocity information to the ADCP.By comparing the simulated velocity value with the actual output value,the flow calibration of the ADCP can be realized.The calibration system uses DDS+PLL(direct digital frequency synthesis and phase-locked frequency synthesis)technology to synthesize high-precision clock signals.The clock signals drive signal acquisition and playback to generate high-precision simulated echo signals.Finally,in a small anechoic water pool,the calibration experiments are carried out for the broadband ADCP with a center frequency of 300 kHz in the small flow velocity range of(0.2~1)m/s.The results show that the measurement uncertainty of this calibration system reaches(0.5%simulated flow velocity+0.005)m/s,which verifies the reliability of the calibration system.

关 键 词：水声计量 声学多普勒流速剖面仪 流速校准 频偏应答 FPGA 时钟合成 不确定度评定 

分 类 号：TB95[一般工业技术—计量学] TB937[机械工程—测试计量技术及仪器]