Doppler ultrasonograph with CORDIC based spectrum analyzer for blood flow velocity estimation
An ultrasonograph system for estimating flow velocity of blood in vessels is proposed which incorporates a spectrum analyzer for observing the Doppler shift occurring due to the flowing blood. The Doppler signal is extracted from the reflected ultrasonic wave by a synchronous demodulation technique and then fed to an analog-to-digital converter through a sample-and-hold circuit. The spectrum analyzer uses FPGA based signal processing chips realizing vector rotations utilising a modified CORDIC algorithm for computing the discrete Hartley transform which is a real valued alternative to the discrete Fourier transform.