Time domain technique to determine mean frequency

Details Time domain technique to determine mean frequency Time domain technique to determine mean frequency

1983-08-26

1985-09-24

Ruehl, Charles A.

Measuring and testing

Volume or rate of flow

By measuring vibrations or acoustic energy

128663, 324 79R, 324 77H, G01F 166

Patent

active

045426570

ABSTRACT:
Accurate estimates of the instantaneous mean frequency of a time varying signal are achieved at favorable and adverse signal-to-noise ratios by an improved time domain approach. Demodulated in-phase and quadrature signals are sampled and delayed. Noise in both terms of a simple arc tangent algorithm, whose denominator has products of time samples shifted at least one time period with respect to itself, is uncorrelated and removed by low pass filtering. One embodiment is a pulsed ultrasonic Doppler system with quadrature detection to measure and display blood velocity as a function of time.

REFERENCES:
patent: 4217909 (1980-08-01), Papadofrangakis et al.
K. S. Miller et al., "A Covariance Approach to Spectral Moment Estimation", IEEE Trans. on Inf. Theory, vol. IT-18, No. 5, Sep. 1972, pp. 588-596.
L. Gerzberg and J. D. Meindl, "Power-Spectrum Centroid Detector for Doppler Systems Applications", Ultrasonic Imaging 2, 232-261, (Jul. 1980).
B. Angelsen, "Instantaneous Frequency, Mean Frequency, and Variance of Mean Frequency Estimators for Ultrasonic Blood Velocity Doppler Signals", IEEE Trans. on Biomed. Engr., BME-28, pp. 733-741, Nov. 1981.

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