Ideal equalizer and ideal equalization method for infinite impulse response filtering

Abstract

The present invention discloses an ideal equalizer and an ideal equalizing method which uses an infinite impulse response (IIR) filtering. The ideal equalizer includes N IRR filters SB1 (f) to SBN (f) for the receiving of an input signal, N gain adjustments coupled with the filters and an adder. The N gain adjustments generate N gain adjustment outputs and the adder accumulates the N gain adjustment outputs to generate an ideal equalizing output signal, and N is more than two. The gain adjustments equalize the N frequency band of the input signal. When the gain adjustments equal actually, the ideal equalizer using IIR filtering has an actually flat frequency response.

Description

Technical field [0001] The present invention relates to an equalizer and related methods, in particular to an ideal equalizer using infinite impulse response filtering and an ideal equalization method. Background technique [0002] Due to the rapid development of audiovisual systems, such as audio systems and television systems, equalizers are important components that related technology developers want to develop, but the quality varies greatly. [0003] Please refer to figure 1 , It is a screenshot of the application WINAMP in the window operating system to illustrate the application example of the equalizer. The application WINAMP is a common sound control application in the window operating system. It contains many operation buttons, mainly indicating the equalizer 100, the volume control 102, and the left and right channel balance 104. This patent application intends to discuss the equalizer 100 components. figure 1 In the figure, the equalizer 100 is placed at 0 decibel (...

AI Technical Summary

Problems solved by technology

image 3 is corresponding to image 3 The ideal flat frequency response graph of the +12dB equalizer 200, people familiar with this art can understand that in the prior art, to achieve this ideal flat frequency response has to pay a high cost of hardware

[0005] Or, the prior art usually adopts a low-cost equalizer solution, roughly selects bandpass filters (bandpass filters) corresponding to ten frequency bands for the equalizer 200, and these bandpass filters are roughly selected by the design tool MATLAB , although the cost is low, but the final quality is very rough, and its frequency response is very uneven, and it cannot achieve a flat frequency response at all, which seriously distorts the quality of audio-visual signals, and people are very sensitive to this audio-visual quality.

For illustrative purposes, see Figure 4 The frequency response of an equalizer with two frequency bands is taken as an example. It has two center frequencies f1 and f2, and the bandwidth of an audio signal 24K is used as a match for illustration. Those skilled in the art choose the two center frequencies by using the design tool MATLAB Two rough bandpass filters BPA and BPB with frequencies f1 and f2 as the center frequency, although the so-called two-band equalizer design can be realized with a simple circuit structure, it can be easily detected that when the equalizer is set to + When the 12dB gain response is reached, the overall frequency response can only meet the standard at the center frequency, and the other frequencies are very uneven, and there is more serious crossover distortion at the crossover of the frequency bands, so after this equalizer, etc. The optimized audio signal is also severely distorted

[0006] On the other hand, as mentioned above, those who are familiar with the art can understand that in the prior art, in order to achieve a high-quality flat frequency response, it is necessary to pay a high-cost hardware price

In order to achieve an ideal flat frequency response, the conventional technology must use inverse Fourier transform (inverse Fourier transform) in the circuit design, set up complex circuits in the time domain, and use a high-performance 32-bit microprocessor, such as the well-known ARM, High-performance microprocessors such as MIPS operate, and those skilled in the art know that these high-performance microprocessors are expensive, and such solutions also severely waste the hardware resources of the microprocessor

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