ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

3aPAa9. Estimation of time-varying phase for multiple tones in atmospheric sound propagation.

John C. Burgess

Dept. of Mech. Eng., Univ. of Hawaii, 2540 Dole St., Honolulu, HI 96822

David I. Havelock

Natl. Res. Council, Ottawa, ON K1A 0S1, Canada

Atmospheric turbulence affects both the amplitude and phase of transmitted sound. Tones at different frequencies will be affected differently. In an earlier presentation [J. C. Burgess and D. I. Havelock, ``Estimation of time-varying phase (instantaneous frequency) in atmospheric sound propagation,'' J. Acoust. Soc. Am. 95, 2838(A) (1994)], the time-varying phase of a single tone was estimated by two methods, one based on an FFT with optimum data windows, the other based on the discrete Hilbert transform. In this presentation, the optimum data window method is extended to multiple tones. Accuracy of the method is examined using a synthesized signal with and without additive noise.