利用超声波多普勒效应进行血流测量,国内已有一些单位开展了这方面的研究工作。在能够得到距离分辨力的方法里,有脉冲多普勒法。这个方法电子线路虽然简单容易实现,但是信噪比低,最大测量距离与最大测量速度之间,距离分辨力与速度分辨力之间存在着矛盾,使得这个方法在理论上就先天不足。为了克服这个缺点而达到距离选通的目的,人们寻找了几种新的方案。M系列就是其中之一。这个方法在提高信噪比等方面具有明显的成效。然而,由于在解调过程中是用M序列自相关技术处理接收信号,所以仍然无法完全除去那些来自非要求检测范围的反射信号,使得整个系统的灵敏度和特异性下降。近期有人提出使用伪随机序列的互相关技术对接收信号进行处理的方 The use of ultrasound Doppler blood flow measurement, some units have carried out research in this area. In the method that can get the distance resolution, there is pulse Doppler method. Although this method is simple and easy to implement electronic circuit, but the signal to noise ratio is low, the maximum measurement distance and maximum measurement speed, distance resolution and speed resolution between the contradictions, making this method in theory, congenitally deficient. In order to overcome this shortcoming and achieve the goal of distance gating, people have looked for several new solutions. M series is one of them. This method has obvious effect in improving signal to noise ratio and other aspects. However, since the received signal is processed by M-sequence autocorrelation during demodulation, the reflected signals from the non-required detection range can not be completely removed, resulting in a decrease in the overall system sensitivity and specificity. Recently, it has been proposed to use the pseudo-random sequence cross-correlation technique to process the received signal