声学多普勒流速快速测量的设计
2021年电子技术应用第5期
张 羽,李永倩,鲍 帅,范寒柏
华北电力大学 电气与电子工程学院,河北 保定071000
摘要: 传统的多普勒流速剖面测量仪将混频正交与低通滤波在软件中实现,存在测量时间长、精度不高等问题。为解决上述问题,采用运算速度更快、内存容量更大的 STM32H743单片机作为主控芯片,同时设计了将信号混频、正交与 FIR 低通滤波在硬件电路中实现的多普勒流速剖面仪,这样大大减少了 CPU 的运算时间,提高了测量精度。运用 FFT 算法进行信号质量分析,利用自相关算法计算出各层流速。通过试验,对测得的多普勒频偏以及流速进行分析,结果表明,系统的设计满足在实际小型河流中的精确测量,具有可行性。
中图分类号: TN913
文献标识码: A
DOI:10.16157/j.issn.0258-7998.200546
中文引用格式: 张羽,李永倩,鲍帅,等. 声学多普勒流速快速测量的设计[J].电子技术应用,2021,47(5):54-58.
英文引用格式: Zhang Yu,Li Yongqian,Bao Shuai,et al. Design of rapid measurement of acoustic Doppler velocity[J]. Application of Electronic Technique,2021,47(5):54-58.
文献标识码: A
DOI:10.16157/j.issn.0258-7998.200546
中文引用格式: 张羽,李永倩,鲍帅,等. 声学多普勒流速快速测量的设计[J].电子技术应用,2021,47(5):54-58.
英文引用格式: Zhang Yu,Li Yongqian,Bao Shuai,et al. Design of rapid measurement of acoustic Doppler velocity[J]. Application of Electronic Technique,2021,47(5):54-58.
Design of rapid measurement of acoustic Doppler velocity
Zhang Yu,Li Yongqian,Bao Shuai,Fan Hanbai
College of Electrical and Electronic Engineering,North China Electric Power University,Baoding 071000,China
Abstract: In traditional Doppler velocity measurement, mixing quadrature and low-pass filtering are generally implemented in software, which results in relatively long measurement time and low accuracy. In order to solve the above-mentioned, STM32H743 single chip computer with faster operation speed and larger memory capacity has been used as the main control chip, and a Doppler velocity profiler is designed by using signal mixing, orthogonal and FIR low-pass filtering in the hardware circuit, which greatly reduces the CPU operation time and improves the measurement efficiency. At the same time, FFT algorithm has been used to analyze the signal quality, and autocorrelation algorithm has been used to calculate the velocity of each layer. Through the experiment, the frequency deviation and velocity are analyzed. The results show that the design of the system can meet the requirements of accurate measurement in actual small streams, and it is feasible.
Key words : orthogonal mixing;Doppler velocity profiler;quality analysis;autocorrelation algorithm
0 引言
传统的声学多普勒流速剖面仪(Acoustic Doppler Current Profiler,ADCP)在单片机内部进行正交变换、FIR滤波来获取多普勒频偏信号的实部和虚部,最后通过自相关算法计算出多普勒频偏,得出流速,由于正交变换和FIR滤波等均在软件中完成,因此数据处理的时间较长,并且硬件电路需要外扩SRAM,不便于电路设计,成本也较高[1]。本系统采用内存1 MB、主频高达400 MHz的STM32H743作为CPU,无需外部SRAM[2],并将回波信号的正交变换以及FIR低通滤波在硬件电路中实现,通过单片机内部16 bit的A/D转换器,同时对两路正交信号进行采样,这样数据处理的速度显著提高,测量的精度也进一步提高,在实际工程中具有很强的实用性。
1 系统的构成及应用原理
多普勒流速剖面测量系统主要由电源系统、发射系统、接收系统、混频滤波系统、正交变换系统、数据采集系统以及通信系统等组成[3]。单片机驱动换能器向水中发射超声波,超声波遇到水中的小颗粒发生漫反射,回波信号经接收匹配电路、LC选频放大电路、二级放大电路后,进入中频混频器与本振信号混频得到中频信号,对中频信号进行选频放大、正交处理后,经过低通滤波器后得到多普勒频偏,进入单片机进行A/D信号采集处理,运算处理完成后,通过Modbus协议进行数据输出[4]。
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作者信息:
张 羽,李永倩,鲍 帅,范寒柏
(华北电力大学 电气与电子工程学院,河北 保定071000)
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