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为了克服常用相干超声多普勒流速计的局限性,作者发明了一种新仪器。该装置采用伪随机信号代替连续波。理论和实验均证明伪随机系统具有许多优点。它的最主要优点是可提高信噪比达20db,而且能降低频率模糊和距离模糊至原来的一半。同随机噪声流速计相比,该系统能测量脉管管壁附近的血流或在超声场中有强固定回波时的血流。为了说明这种新仪器的性能,我们将介绍一些由经皮法获得的结果。
In order to overcome the limitations of commonly used coherent ultrasound Doppler velocimeters, the authors invented a new instrument. The device uses pseudo-random signal instead of continuous wave. Both theory and experiment prove that pseudo-random system has many advantages. Its main advantage is to improve the signal to noise ratio of 20db, but also to reduce the frequency of ambiguity and blurred the original half. Compared to a stochastic noise anemometer, the system measures blood flow near the vessel wall or blood flow with a strong fixed echo in the ultrasound field. To illustrate the performance of this new instrument, we will introduce some of the results obtained by transdermal methods.