Claims
- 1. A method of determining a time delay between a first signal received at a first sensor and a second signal received at a second sensor comprising:analyzing the first signal to derive a plurality of first signal channels at different frequencies; analyzing the second signal to derive a plurality of second signal channels at different frequencies; detecting a first feature occurring at a first time in one of the first signal channels; detecting a second feature occurring at a second time in one of the second signal channels; matching the first feature having a first timestamp applied based on a first event with the second feature having a second timestamp applied based on a second event; comparing the first time to the second time to determine the time delay; and associating the time delay with a continuity criteria to determine whether the first signal and the second signal originates from a sound source and to track the sound source.
- 2. A method of determining a time delay as recited in claim 1 wherein the first feature includes a signal local maximum.
- 3. A method of determining a time delay as recited in claim 1 wherein the first feature includes a set of signal local maximums.
- 4. A method of determining a time delay as recited in claim 1 wherein the first feature includes a signal local minimum.
- 5. A method of determining a time delay as recited in claim 1 wherein the first feature is a signal local maximum and wherein the amplitude of signal local maximum is used to match the first feature with the second feature.
- 6. A method of determining a time delay as recited in claim 1 wherein the first feature is a signal local maximum and wherein the signal local maximum is interpolated from sampled points.
- 7. A method of determining a time delay as recited in claim 1 wherein the first feature is a zero crossing.
- 8. A method of determining a time delay as recited in claim 1 wherein the first feature is a zero crossing and wherein whether the zero crossing is positive going or negative going is used to match the first feature with the second feature.
- 9. A method of determining a time delay as recited in claim 1 wherein the first feature is a peak of an envelope function.
- 10. A method of determining a time delay as recited in claim 1 further including matching a plurality of features in a plurality of channels and determining a plurality of time delays and comparing the time delays to derive a single time delay that corresponds to a single source.
- 11. A method of determining a time delay as recited in claim 1 further including matching a plurality of features in a plurality of channels and determining a plurality of time delays and comparing the time delays to validate the event time delay.
- 12. A method of determining a time delay as recited in claim 1 wherein the time delay is used to localize a sound source.
- 13. A method of determining a time delay as recited in claim 1 wherein the time delay is used to localize a sound source for and a video camera is configured to point at the sound source.
- 14. A method of determining a time delay as recited in claim 1 wherein the time delay is used to localize a sound source and background sounds not emanating from the source are filtered.
- 15. A method of determining a time delay as recited in claim 1 wherein matching the first feature with the second feature includes imposing a maximum possible time delay to remove ambiguities.
- 16. A method of determining a time delay as recited in claim 1 wherein the first feature and the second feature are periodic and wherein comparing the first time to the second time to determine the time delay includes imposing a maximum possible time delay to determine which feature preceded the other.
- 17. A system for determining a time delay between a first signal and a second signal comprising:a first sensor that receives the first signal; a second sensor that receives the second signal; a spectrum analyzer that analyzes the first signal to derive a plurality of first signal channels at different frequencies and that analyzes the second signal to derive a plurality of second signal channels at different frequencies; a feature detector that detects a first feature occurring at a first time in one of the first signal channels and that detects a second feature occurring at a second time in one of the second signal channels; an event register that records the occurrence of the first feature and the second feature; and a time difference calculator that compares the first time to the second time to determine the time delay, matching the first feature having a first timestamp applied based on a first event with the second feature having a second timestamp applied based on a second event, and associating the time delay with a continuity criteria to determine whether the first signal and the second signal originates from a sound source and to track the sound source.
- 18. A computer program product for determining a time delay between a first signal received at a first sensor and a second signal received at a second sensor, the computer program product being embodied in a computer readable medium and comprising computer instructions for:analyzing the first signal to derive a plurality of first signal channels at different frequencies; analyzing the second signal to derive a plurality of second signal channels at different frequencies; detecting a first feature occurring at a first time in one of the first signal channels; detecting a second feature occurring at a second time in one of the second signal channels; matching the first feature with the second feature matching the first feature having a first timestamp applied based on a first event with the second feature having a second timestamp applied based on a second event; comparing the first time to the second time to determine the time delayed; and associating the time delay with a continuity criteria to determine whether the first signal and the second signal originates from a sound source and to track the sound source.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to co-pending U.S. patent application Ser. No. 09/534,682 by Lloyd Watts filed Mar. 24, 2000 entitled: “EFFICIENT COMPUTATION OF LOG-FREQUENCY-SCALE DIGITAL FILTER CASCADE” which is herein incorporated by reference for all purposes.
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