Electrical audio signal processing systems and devices – Noise or distortion suppression
Reexamination Certificate
2006-01-30
2010-12-07
Lee, Ping (Department: 2614)
Electrical audio signal processing systems and devices
Noise or distortion suppression
C360S031000
Reexamination Certificate
active
07848530
ABSTRACT:
According to this invention, mechanical noise from a noise source of a pre-identified device can be removed, while tracing a change in gain of acoustic wave data, and noise is removed by tracing a change over time of the noise source. To this end, the gain of a signal from a microphone is automatically adjusted by an Auto level control unit (ALC). A threshold according to the gain of the ALC is stored in a register. A comparator compares audio data from the ALC with the threshold, generates weighting coefficients k and 1−k based on the comparison result, and outputs them to weighting coefficient multipliers. The weighting coefficient multipliers and an adder calculate a weighted average value of data in a memory that stores weighting coefficients of old frames and the input acoustic wave data, and update the contents of the memory by the calculation result. With this update processing, the memory stores only a NOISE component. A level adjusting unit adjusts data read out from the memory according to the current gain of the ALC. An adder subtracts the adjusted data from the input acoustic wave data, and outputs data after noise removal.
REFERENCES:
patent: 07-177596 (1995-07-01), None
patent: 11-205891 (1999-07-01), None
Translation of JP 11205891, Hanada, Jul. 30, 1999.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Lee Ping
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