Soft decision signal estimation
First Claim
1. A method for estimating a speech signal contained within a received signal including both a speech component and a noise component, said method comprising:
- a) inputting the received signal to a receiver filter and a voice activity detector;
b) computing a likelihood ratio within said voice activity detector based on the power of said received signal;
c) computing a speech probability estimate within said voice activity detector based on said likelihood ratio and the a priori probability of speech;
d) outputting said speech probability estimate from said voice activity detector;
d) filtering said received signal within said receiver filter to obtain a filter output signal; and
e) combining said filter output signal with said speech probability estimate output from said voice activity detector to produce a soft estimate of said speech signal.
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Accused Products
Abstract
A method for signal detection uses a likelihood ratio derived from the received signal to produce an estimate of a speech signal that has been corrupted by noise during transmission. The received signal is input to a receiver filter and a voice-activity detector. The receiver filter filters the received signal to produce a filter output signal. The voice-activity detector generates a likelihood ratio based on the received signal, which is then used to produce a speech-probability estimate indicating the probability that the received signal includes a speech signal. The filter output signal is combined with the speech-probability estimate output from the voice-activity detector to generate a soft estimate of the original speech signal.
32 Citations
24 Claims
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1. A method for estimating a speech signal contained within a received signal including both a speech component and a noise component, said method comprising:
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a) inputting the received signal to a receiver filter and a voice activity detector;
b) computing a likelihood ratio within said voice activity detector based on the power of said received signal;
c) computing a speech probability estimate within said voice activity detector based on said likelihood ratio and the a priori probability of speech;
d) outputting said speech probability estimate from said voice activity detector;
d) filtering said received signal within said receiver filter to obtain a filter output signal; and
e) combining said filter output signal with said speech probability estimate output from said voice activity detector to produce a soft estimate of said speech signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for estimating a speech signal contained within a received signal including both a speech component and a noise component, said method comprising:
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a) computing a likelihood ratio based on the power of said received signal;
b) computing a speech probability estimate based on said likelihood ratio and the a priori probability of speech;
c) filtering said received signal with a receiver filter to obtain a filter output signal; and
d) combining said filter output signal with said speech probability estimate to produce a soft estimate of said speech signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A soft-decision signal detector for producing a soft estimate of a received speech signal contained in a received signal including both speech and noise components, said signal detector comprising:
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a) a voice activity detector for producing a speech probability estimate indicative of the probability of speech being present in said received signal, said voice activity detector including;
1) a voice detection filter for producing a filtered output based on said received signal;
2) a power detector connected to said voice detection filter to calculate a power estimate based on the output of said voice detection filter;
3) a likelihood estimator connected to said power detector to calculate a likelihood ratio based on said power estimate;
4) a speech probability estimate connected to said likelihood calculator to calculate said speech probability estimate based on said likelihood ratio;
b) a receiver filter to filter said received signal and produce a filtered output signal; and
c) a signal combiner for combining said filter output signal and said speech probability estimate to obtain a soft estimate of said speech signal. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification