点式单波束多普勒测流系统的设计方法

为了加快多普勒流速计算速度和提高系统稳定性,提出基于FPGA技术的多普勒测速的设计方法,其中包括信号发射电路和信号接收电路。首先通过M码进行二相相移键控信号的调制,减少了回波误差、增加信号发射能量,有效地降低了水中超声波的能量耗散对信号提取的影响。然后对回波信号进行二相解调,并利用复自相关算法进行分析处理。最后,通过测速实验对所提方法进行验证。实验结果表明,所提方法不仅具有较低的实验误差而且具有较高的可靠性。

A Design Method of Dot-mode single-beam Doppler flow system

In order to speed up the Doppler velocity calculation and improve the system stability, the design method is proposed based on FPGA technology, including signal transmission circuit and signal receiving circuit. Firstly, the modulation of the binary phase shift keying signal is carried out by M code, which reduces the echo error and increases the energy of signal transmission, and effectively reduces the influence which the energy dissipation of the ultrasonic in the water to the signal extraction. Then the echo signal is demodulated by two-phase, and analyzed and processed by complex autocorrelation algorithm. Finally, the proposed method is verified by the velocity measurement experiment. The experimental results show that the proposed method not only has low experimental error but also has high reliability.