Performance of the mean frequency Doppler modulator

Abstract

The mean frequency Doppler demodulator is of interest for quantitative measurement of blood flow, particularly in small or deep-lying vessels. It is thus desirable that the various potential sources of error be considered, and that their effects on its performance be quantified where possible. This paper analyzes the effects of interfering noise, more than one vessel falling within the Doppler sample volume, Doppler filtering, frequency aliasing, and double-sidebanding of the Doppler signal. The analysis applies to either frequency offset or non-offset Doppler systems, and a variety of blood velocity distributions is considered. It is shown that, in a number of instances, the errors can be predicted and therefore corrected. Experimental results are presented confirming the theoretical analysis.