Filter bank determination of discrete tone frequencies
First Claim
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1. A ratio detecting filter bank having ratio detectors and comprising:
- at least one pair of bandpass filters, each having a different center frequency, said bandpass filters having frequency response characteristics to cover a desired frequency band, whereineach said filter has a first frequency response based on a first standard deviation below a said center frequency and a second frequency response based on a second standard deviation above the same said center frequency, said first and second standard deviations being different and, whereinsaid second standard deviation for a filter of said pair at a lower center frequency matches a first standard deviation for a filter of said pair with a higher center frequency.
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Abstract
Specifically shaped filter responses enable power or amplitude measurements at the filter outputs to be simply transformed into accurate measurements of some desired function of the frequency (such as the frequency itself or log (frequency)) of any discrete tones within the filters'"'"' bandwidths. The invention can be used in conjunction with Fast Fourier Transform based filter banks. In cases where discrete tones are harmonically related, as in speech, the invention enables a simple determination of a weighted average of the harmonics'"'"' fundamental frequency, without having to first estimate the individual harmonics'"'"' frequencies.
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Citations
7 Claims
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1. A ratio detecting filter bank having ratio detectors and comprising:
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at least one pair of bandpass filters, each having a different center frequency, said bandpass filters having frequency response characteristics to cover a desired frequency band, wherein each said filter has a first frequency response based on a first standard deviation below a said center frequency and a second frequency response based on a second standard deviation above the same said center frequency, said first and second standard deviations being different and, wherein said second standard deviation for a filter of said pair at a lower center frequency matches a first standard deviation for a filter of said pair with a higher center frequency. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for characterizing discrete signals in an input multicomponent signal, comprising:
a receiver having a plurality of filters, said receiver receiving as input said multicomponent signal, said receiver comprising means for estimating power versus frequency of said multicomponent signal, wherein each filter in said plurality of filters used for estimating has an amplitude/frequency response suitable for forming ratio detectors, and wherein said ratio detectors have outputs, certain ones of said outputs forming a consistent set of estimates of frequency and amplitude of a component of said input multi-channel signal.
Specification