Design On Portable Power M-mode Transcranial Doppler Ultrasonic Measurement System

The high mortality and disability of cerebrovascular diseases threaten the health of human,and the incidence rate increases sharply with the average age getting much younger,which makes the early warning and diagnosis of cerebrovascular diseases become one of the urgent problems in the academic research world.Transcranial Doppler Ultrasoound Measurment Equipment is characterized by no radition,no trauma,low cost and good real-time performance,and all these make TCD used widely in the hemodynamic study and clinical detection.However,the traditional TCD has the disadvantages such as difficulty in locating the ultrasonic window and intracranial vascular,and it is hard to capture the trajectory of microembolus.To overcome the above problems,we design a protable power-Motion mode TCD system.The analog circuit of the system realizes functions such as ultrasonic transmission and reception,filtering and amplification,demodulation and phase adjustment.The digital circuit with state machine design as the core is based on FPGA,which produces clock signal for different modules and the control timming of the whole system,adopts the dual-channel high-speed AD sampling and uses two FIFO memories to ensure data continuity.In this thesis,high-speed USB is used for interacing between hardware and PC,as well as a bridge to transmit information.The USB design includes firmware programming based on microprocessor chip and application development on PC.Both the two parts cooperate with each other to complete different transfer modes.The software uses multi-threads mechanism to improve efficiency of system resource allocation and real-time capability.PMD imaging technique is applied to display the whole state of blood vessels on the ditrection of ultrasonic beam,which can make the blood vessels found easier,then utilizes STFT and pseudo-color processing to provide the doctors with more detailed information about morphology of vascular and hemodynamic parameters.The system is realized by hardware circuit design,USB firmware driver development and PC data processing modules,which has advantages such as portable and good real-time performance.The device equips with different types of probes to meet different needs of detection,and plays an important role in prevention and diagnosis of cerebrovascular diseases.