| Abstrakt: |
A method has been developed for determination of the frequency-averaged, mean-squared coherence (FMSC) of broadband transient acoustic signals, similar to underwater explosions. It has many of the properties of the more conventional mean-squared coherence (MSC), including a systematic bias, dependent upon the number of spectral values used in the estimate. The method has been demonstrated using a model of the underwater explosive direct arrival transient signal. As FMSC is averaged over several frequencies the method compromises the functional knowledge of frequency dependence to achieve stable and relatively unbiased values. Results are compared to MSC, utilizing a calibration method developed during the study. The relative level of coherence between separate similar transient acoustic processes can be determined when the signals are precisely time aligned. FMSC can be used as the means of making this time alignment, thus making the necessary computations internally consistent. [Work supported by U.S. Navy, NORDA, Code 242, Arctic Acoustics.] [ABSTRACT FROM AUTHOR] |
