Comparison of zero-crossing counter to FFT spectrum of ultrasound Doppler.
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abstract
Continuous wave analog Doppler velocimeters have been used for a number of years for the detection of blood flow in peripheral vessels, The evaluation of these Doppler waveforms using spectral analysis has increased in popularity since the advent of microcomputer based systems, Zero-crossing analysis, on the other hand, has the advantage of much simpler implementation and an ahility to follow the dominant frequency in a noisy environment. In order to compare these two spectrum analysis approaches under controlled conditions, Doppler data was obtained from a normal carotid, popliteal, and radial artery. It was found that the results of a digital zero-crossing counter-mean frequency estimate and the first moment of the FFT generated spectra were comparable for high signal-to-noise ratio, as in the case of the carotid arterial waveform. However, the digital zero-crossing with thresholding was a more accurate representation of the expected velocity versus time waveforms in the case of low signal-to-noise ratio Doppler obtained from the popliteal and radial arteries. 1988 IEEE