Multi-channel signal separation
AssigneeMassachusetts Institute of Technology
InventorsEhud Weinstein, Meir Feder, Alan V. Oppenheim
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Abstract
A system separates unknown signals which have been combined together through unknown linear filters and for which observations at multiple sensors are made. In a two channel circuit with two inputs and two sensors, the reconstructed source signals are assumed to be decorrelated such that the cross-correlation between the reconstructed source signals is near zero. The transfer functions which represent the crosstalk processes are estimated. The output signals are detected and the transfer functions are recursively solved. A reconstruction filter is used to recover the original input signals.
Claims44
A signal processing system comprising:
- a plurality of detectors for detecting source signals subjected to a generating system transfer function;
- a processor for receiving the detected signals and producing a reconstruction filter for filtering the detected signal to produce reconstructed source signals, the reconstruction filter being produced such that correlation between reconstructed source signals is forced to approach zero even when each detector receives source signals from plural sources;
- and
- said reconstruction filter for receiving the detected signals to generate a reconstruction of the various source signals without interference from any of the other source signals.
A signal processing system comprising:
- a first detector for receiving at least one source signal subjected to a generating system transfer function;
- a second detector for receiving at least one source signal subjected to said generating system transfer function;
- a reconstruction filter including a first transfer function to which a first signal from the first detector is applied and a second transfer function to which a second input signal from the second detector is applied, the output of the first transfer function being subtracted from the second input signal and the output of the second transfer function being subtracted from the first input signal;
- such that the reconstruction filter for filtering the first and second signals produce reconstructed first and second source signals with a correlation that is forced to approach zero even when each detector receives source signals from plural sources.
A method of multichannel source signal separation, wherein said source signals are subjected to a transfer function, comprising the steps of:
- detecting a plurality of observed signals from at least one source signal subjected to the transfer function;
- and
- processing the detected signals and producing a reconstruction filter for filtering the detected signal to produce reconstructed source signals such that the correlation between the various reconstructed source signals is forced to approach zero even when each observed signal receives source signals from plural sources.
A signal processing system, for reconstructing first source signal S.sub.1 and a second source signal S.sub.2 which are subjected to a generating transfer function, comprising
- (a) a first detector which produces a first observed signal y.sub.1 from at least one source signal subjected to said transfer function;
- (b) a second detector which produces a second observed signal y.sub.2 from at least one source signal subjected to said transfer function;
- (c) a reconstruction filter including:
- (i) a first filter H.sub.21 which processes the first observed signal y.sub.1 and produces a first output signal U.sub.1,
- (ii) a second filter H.sub.12 which processes the second observed signal y.sub.2 and produces a second output signal U.sub.2,
- (iii) a first subtractor which subtracts V.sub.2 from Y.sub.1 to produce V.sub.1,
- (iv) a second subtractor which subtracts U.sub.1 from Y.sub.2 to produce V.sub.2,
- (v) a processing transform which converts the signals V.sub.1 and V.sub.2, respectively, into reconstructed source signals, S.sub.1 and S.sub.2, respectively, wherein the correlation between the reconstructed source signals is forced to approached zero, even when each detector receives source signals from plural sources.
A system for enhancing speech in a noise environment, where both the speech and noise are subjected to a generating system transfer function, comprising:
- a first microphone near a speaker which produces a first observed signal y.sub.1, including at least one of speech and noise components,
- a second microphone near a noise source which produces a second observed signal Y.sub.2, including at least one of speech and noise components,
- a processor for receiving the first and second observed signals, y.sub.1 and y.sub.2, and producing a reconstruction filter for filtering the detected signals to produce reconstructed source signals,
- said reconstruction filter producing separate reconstructed speech and noise signals such that the correlation between the reconstructed signals is forced to approach zero even when each microphone detects both speech and noise components.
A signal enhancing system in an underwater acoustic environment, where both a source signal and noise are subjected to a generating system transfer function, comprising
- a sonar array for producing and receiving ultrasonic signals, wherein the received signals represent a plurality of first observed signals Y.sub.1 -Y.sub.p, including at least one of source signal and noise components,
- a microphone near a noise source which produces a second observed signal Y.sub.2, including at least one of source signal and noise components,
- a processor for receiving the first and second observed signals Y.sub.1 --Y.sub.p and Y.sub.2, and producing a reconstruction filter for filtering the detected signals to produce reconstructed source signals,
- said reconstruction filter producing separate reconstructed signals where the correlation between the reconstructed signals is forced to approach zero, even when the sonar array and the microphone both detect source signal and noise components.
Dependencies are inferred from the claim text.