The research on the cardiovascular and cerebrovascular hemodynamics can help to interpret the cause of disease and diagnoses of the cardiovascular and cerebrovascular disease. It is important to collect and analyze the blood flow activity. Now Doppler Ultrasound is the newest technique to supply the data of the cardiovascular and cerebrovascular hemodynamics non-invasively

simply and effectively. In this paper

a digital system was designed. It can get the frequency spectrum image of Doppler Ultrasound's activities. Through the analysis and research on the output data format of a printer

the frequency spectrum image will be stored by the familiar format of image files. With the image manipulation technique

the time series data of the blood flow activity can be obtained and they are fit for various nonlinear analysis. By the system the original blood flow activity can be observed

and the changes of the data in the experiments can also be detected real-timely. It is proved by actual examples that this system is feasible

and the time series data of the blood flow activity obtained are exactly. It can offer assistance for the further study of the cardiovascular and cerebrovascular disease. It can also provide the foundation for uniting nonlinear science and ultrasonic diagnosis in medicine.