Research Lab. of Precision Machinery and Electronics, Tokyo Institute of Technology
Modulated ultrasonic Doppler method enables to observe velocity profile in human body. Systems on this method are introduced here. These are classified into two types, namely gate type and correlation type.Pulsed ultrasonic Doppler system belongs to gate type. M-sequence ultrasonic Doppler system belongs to correlation type. Periodicity of modulating and demodulating signals gives these systems the limitation in the product of the maximum Doppler velocity and observing range. Some systems are proposed to overcome this limitation.