中文摘要：

虽然脉冲多普勒系统测量血流速度时，能够确定距离，但可测速度范围受频率混淆限制，同时多普勒信号的信噪比差．连续波多普勒系统提供了较高的多普勒信号的信噪比，并没有可测速度限制，但无法提供距离信息．线性调频及正弦调频连续波测量系统，能够提供拥有距离信息的高信噪比多普勒信号，同时杂波功率低，但由于多普勒信号频谱具有周期性，存在一定的距离模糊．针对存在的问题，提出基于混沌调频连续波的超声多普勒血流速度测量方法，它不仅具有较高的信噪比，而且由于多普勒信号频谱无周期性，因此不存在距离模糊．经过原理分析及仿真实验，验证了混沌调频连续波的有效性．

英文摘要：

Although a pulsed-wave （PW） Doppler system can measure blood velocity with range information, measurable velocity is limited by frequency aliasing, and signal-noise-ratio （SNR） is poor. Continuous wave （CW） Doppler system offers a higher SNR in Doppler signal and no measurable velocity limitations but does not provide ranging information. Linear frequency-modulated continuous wave （LFMCW） and sine frequency-modulating continuous wave are able to provide high SNR Doppler signals with ranging information, and low clutter power, but with a certain range ambiguity due to signal periodicity of the Doppler signal spectrum. Various efforts have been made to improve the SNR, range resolution, and velocity limitations with FMCW Doppler system. An ultrasonic doppler blood flow velocity measurement system based on chaotic FMCW is proposed which has a higher SNR with no range ambiguity because of the aperiodicity of the Doppler s~gnal spectrum. Principle analysis and experimental simulation show that the effectiveness of the new system is verified.