5311453 : Variable point sampling

ABSTRACT:   A method and system by which the number of samples used to characterize the noise cycle of an active noise cancellation system varies dynamically as a function of the fundamental operating frequency of the system.

U.S. REFERENCES:

1 patent references this one

Patent No. Inventor Issued Title 4153815 Chaplin et al. 5 /1979 Active attenuation of recurring sounds 4336593 Takase 6 /1982 Data processing system for electronic control of automotive vehicle devices with noise prevention 4417098 Chaplin et al. 11 /1983 Method of reducing the adaption time in the cancellation of repetitive vibration 4490841 Chaplin et al. 12 /1984 Method and apparatus for cancelling vibrations 4639885 Spock et al. 1 /1987 EMI suppression for electronic engine control frequency signal inputs 4878188 Ziegler, Jr. 10 /1989 Selective active cancellation system for repetitive phenomena 4947356 Elliott et al. 8 /1990 Aircraft cabin noise control apparatus 5007007 van Zanten et al. 4 /1991 Circuitry for converting a measurement signal disturbed by a disturbance function into an undisturbed signal 5029118 Nakajima et al. 7 /1991 Periodic noise canceling system and method 5119321 Burton, Jr. et al. 6 /1992 Adaptive threshold suppression of impulse noise 5157596 Alcone 10 /1992 Adaptive noise cancellation in a closed loop control system EXEMPLARY CLAIM(s): Show all 4 claims We claim: 1. In a digital, synchronous, noise cancellation system for canceling the frequency components, the method of maintaining the sampling rate and required processing resources within a small range while the fundamental noise cycle varies over a large range, said method comprising determining the highest frequency to be processed, determining the current noise cycle rate, changing the number of sample points per noise cycle dependent upon the noise cycle rate and the highest frequency to be processed. RELATED U.S. APPLICATIONS: none FOREIGN APPLICATION PRIORITY DATA: none FOREIGN REFERENCES: none OTHER REFERENCES: none PRIMARY/ASSISTANT EXAMINERS: Harvey; Jack B.; Peeso; Thomas ADDED TO DATABASE: Aug. 23, 1996