Communication system noise cancellation power signal calculation techniques

• US 20060247923A1
• Filed: 06/28/2006
• Published: 11/02/2006
• Est. Priority Date: 03/28/2000
• Status: Active Grant

• Current Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Original Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Inventors: Marchok, Daniel J., Dunne, Bruce E., Chandran, Ravi
• Granted Patent: US 7,424,424 B2
• Time in Patent Office: Days
• US Class Current: 704/211
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 21/02 Speech enhancement, e.g. noise reduction or echo cancellation reducing echo effects in line transmission systems H04B3/20; echo suppression in hands-free telephones H04M9/08
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain

Abstract

In order to enhance the quality of a communication signal derived from speech and noise, a filter divides the communication signal into a plurality of frequency band signals. A calculator generates a plurality of power band signals each having a power band value and corresponding to one of the frequency band signals. The power band values are based on estimating, over a time period, the power of one of the frequency band signals. The time period is different for different ones of the frequency band signals. The power band values are used to calculate weighting factors which are used to alter the frequency band signals that are combined to generate an improved communication signal.

Claims

1. In a communication system for processing a communication signal derived from speech and noise, apparatus for enhancing the quality of the communication signal comprising:

a frequency band divider arranged to divide the communication signal into a plurality of frequency band signals; and

a calculator generating a plurality of power band signals having power band values and corresponding to the frequency band signals, the power band values being based on estimating over time periods the power of the frequency band signals, the time periods being different for at least two of the frequency band signals, calculating weighting factors based at least in part on the power band values, altering the frequency band signals in response to the weighting factors to generate weighted frequency band signals and generating a communication signal with enhanced quality in response to the weighted frequency band signals.