The conventional Doppler ultrasonic blood flow measurement systems use analog circuits to complete the signal acquisition and processing. Such instruments are susceptible to external electromagnetic interference,environment temperature changes and other factors,and it's difficult to implement modern signal processing algorithms to achieve more advanced detections,such as multi-depth detection,power M-mode Doppler and coded excitation. In this paper,a digital Doppler ultrasonic blood flow signal acquisition and processing system was designed,combined with the classic " autocorrelation technology" to achieve multi-depth detection and power M-mode Doppler. And the axial resolution of the system based on the 2-cycle base 13-chip Barker coded excitation was much better than the conventional method. The feasibility of the system was proved by the phantom test. In addition,the human cerebral artery measurement showed that the system could display the blood information on the path of the ultasound wave,and it was useful for the vessel positioning and identification.%传统超声多普勒血流测量仪器使用模拟电路来完成信号采集与解调处理,此类系统容易受外界电磁环境、温度变化等因素的干扰,也难以运用现代信号处理技术来实现更高级的检测功能,例如多深度检测、功率M型多普勒血流成像以及编码激励成像等.本研究设计了一种全数字的超声多普勒血流信号采集处理系统,结合经典的自相关技术,实现了多深度检测和功率M型多普勒血流成像,并采用2周期基础码调制的13位Barker码编码激励方法,得到远高于传统方法的轴向空间分辨率.为验证该系统的有效性,首先利用该系统对多普勒体模进行检测实验研究,证明该系统能有效提高轴向空间分辨率；然后通过对大脑中动脉、前动脉血流检测,表明该系统可以显示出超声波发射方向上整个深度的血流信息,有利于血管的定位和识别.
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