| 摘要 |
Sampling of a captured signal is synchronized to a tonal which may be unstable in frequency detected in the signal to cause the detected tonal and all of its harmonics, sub-harmonics and fundamental to appear to have a substantially constant frequency relative to the sampling rate to facilitate observation and other signal processing even if some related signals are otherwise undetectable amid noise. By adjusting an integration period of a corresponding output of a fast Fourier transform to extract an intrinsic bandwidth, substantial signal processing gain can be obtained for the tonal and harmonically related components of the signal, even if some harmonically related signals are otherwise undetectable. Signal processing may be performed in either the time domain or the frequency domain. Recursive processing to observe as many unrelated tones as possible by grouping of tones which are harmonically related. Further recursive processing supports detection of relationships between acoustic signal sources by observation of variations from harmonic frequencies of harmonically related signal components.
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