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。
中圖分類號： TN913 文獻標識碼： A DOI：10.16157/j.issn.0258-7998.200546 中文引用格式： 張羽，李永倩，鮑帥，等. 聲學多普勒流速快速測量的設計[J].電子技術應用，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
傳統(tǒng)的聲學多普勒流速剖面儀(Acoustic Doppler Current Profiler，ADCP)在單片機內部進行正交變換、FIR濾波來獲取多普勒頻偏信號的實部和虛部，最后通過自相關算法計算出多普勒頻偏，得出流速，由于正交變換和FIR濾波等均在軟件中完成，因此數(shù)據處理的時間較長，并且硬件電路需要外擴SRAM，不便于電路設計，成本也較高[1]。本系統(tǒng)采用內存1 MB、主頻高達400 MHz的STM32H743作為CPU，無需外部SRAM[2]，并將回波信號的正交變換以及FIR低通濾波在硬件電路中實現(xiàn)，通過單片機內部16 bit的A/D轉換器，同時對兩路正交信號進行采樣，這樣數(shù)據處理的速度顯著提高，測量的精度也進一步提高，在實際工程中具有很強的實用性。
