Graphic Equalizer Gain Compensation for Cascaded Filter Leakage
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Solution Overview
Problem
Cascaded digital equalization filters experience gain leakage among adjacent bands, affecting the overall system response due to the magnitude response interaction between individual filters.
Innovation Solution
Compensating for leak gain by determining individual filter gains through estimation and modification of gain parameters, using a cascade of peak/notch and shelf filters with band-edge frequencies aligned, and employing low-complexity computations to achieve desired gains in graphic equalizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If individual tunable equalization filters are cascaded to provide graphic equalization filtering, then control of gains in individual frequency bands is achieved, but gain leakage among adjacent bands occurs affecting the overall system response
Solution Approach 1:
The patent implements a feedback mechanism where the desired overall gain for each frequency band is specified by the user, and the system automatically computes the individual filter gains required to achieve these desired gains while compensating for leakage effects from adjacent bands. This closed-loop approach ensures that the actual system response matches the desired response despite the presence of gain leakage.
Solution Approach 2:
The patent transforms the problem by changing the parameters from directly controlling individual filter gains to controlling the desired overall gains. By formulating a system of equations that relates desired gains to individual filter gains, the patent enables precise control of the overall system response while automatically accounting for and compensating for gain leakage among adjacent bands.
2Adaptability or versatility
If cascaded equalization filters are used with individual gain control, then user adjustments of gains in frequency bands are enabled, but the magnitude response of one filter affects the responses of other filters causing leak gain
Solution Approach 1:
The system uses feedback by taking the desired gains as input and computing the actual individual filter gains that will produce those desired gains when accounting for interactions with adjacent filters. This ensures that user adjustments are accurately reflected in the final system response despite the coupled nature of cascaded filters.
Solution Approach 2:
The patent performs preliminary computation of individual filter gains before the filters are actually applied to the signal. By solving the system of equations in advance to determine the correct individual gains that will achieve the desired overall gains, the patent preemptively compensates for the expected gain leakage effects.
3Manufacturing precision
If compensation for leak gain is implemented through gain determination in terms of desired gains, then accurate overall response is achieved, but computation complexity increases
Solution Approach 1:
The patent simplifies the computational problem by changing the approach from directly calculating individual filter gains to working with desired gains as the primary parameters. This parameter transformation leads to a system of linear equations that can be solved efficiently using standard mathematical techniques, reducing the computational burden compared to iterative optimization methods.
Data Source
AI summary
Graphic equalizer as a cascade of equalization filters with the gain of each individual filter compensated for the gain leakage from other filters. A linear approximation allows individual filter gains to be set to give desired frequency responses.