Zero-phase on-line DC removal filter for road noise active control system

An active control system and DC removal technology, applied in impedance networks, digital technology networks, electrical components, etc., can solve problems such as system failure to converge, excessive energy accumulation, and reduce noise reduction, to improve stability and reliability. Low computational cost and effect of eliminating DC components

Active Publication Date: 2019-08-06
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the introduction of the DC component, the algorithm will accumulate more and more energy during the iterative process, so that the system cannot converge
[0003] Although the built-in digital filter in Matlab can filter out the DC component, it also introduces a phase difference, which changes the coherence between the reference signal and the noise signal, thereby reducing the amount of noise reduction and even causing the system to diverge.

Method used

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  • Zero-phase on-line DC removal filter for road noise active control system
  • Zero-phase on-line DC removal filter for road noise active control system
  • Zero-phase on-line DC removal filter for road noise active control system

Examples

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Embodiment

[0026] like figure 1 As shown, the present invention provides a zero-phase online direct current removal filter for an active road noise control system, which can realize online direct current removal without introducing phase changes.

[0027] The expression for the digital filter in this example is:

[0028]

[0029] The meaning of this expression is to subtract the average value of the signal collected in the previous period from the signal obtained by the current sampling, so as to achieve the effect of removing DC.

[0030] The transfer function of the digital filter is:

[0031]

[0032] The amplitude-frequency response and phase-frequency response of the transfer function are as follows figure 2 and image 3 shown.

[0033] like figure 2 As shown, the high-frequency part of the amplitude-frequency response of the filter is basically maintained around 0dB, and although there is a little fluctuation below 5Hz, it will soon converge to 0dB. It shows that the ...

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Abstract

The invention relates to a zero-phase on-line DC removal filter for a road noise active control system. The zero-phase on-line DC removal filter comprises a first delayer, wherein the first delayer isused for delaying an input signal x(n) by fs unit lengths to obtain a delay signal x(n-fs); a first subtracter, taking an input signal x (n) and a delay signal x (n-fs) as input and subtracting the input signal x (n) and the delay signal x (n-fs) to obtain an output difference signal w (n); a first adder, taking the difference signal w (n) and the intermediate delay signal r (n-1) as input and adding the input to obtain an intermediate signal r (n); a second delayer, used for delaying the intermediate signal r (n) by one unit length; and a first multiplier, used for dividing the intermediatesignal r (n) by the sampling frequency fs to obtain an average value of the input signal x (n), and a second subtracter, used for subtracting the input signal x (n) from the average value to obtain adirect-current-removed output signal y (n). Compared with the prior art, the zero-phase on-line DC removal filter can realize online DC component removal, does not introduce phase change, and is suitable for online removal of DC components in active noise control.

Description

technical field [0001] The invention relates to the field of digital signal processing, in particular to a zero-phase online direct current removal filter used in an active road noise control system. Background technique [0002] In the noise active control system, due to the characteristics of the sensor and hardware, there will be a DC component when measuring the reference signal and error signal. The mainstream algorithm of noise active control system is LMS algorithm. Due to the introduction of the DC component, the algorithm will accumulate more and more energy during the iterative process, so that the system cannot converge. [0003] Although the built-in digital filter in Matlab can filter out the DC component, it also introduces a phase difference, which changes the coherence between the reference signal and the noise signal, thereby reducing the amount of noise reduction and even causing the system to diverge. Contents of the invention [0004] The object of th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H17/02
CPCH03H17/0223
Inventor 孟德建皮雄飞张立军张希玉
Owner TONGJI UNIV
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