JPH1155782A - Distortion removal device, coefficient deciding method for the same, processing speaker system, multiprocessor and amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove non-linear distortion by inputting a test signal to a non-linear system, measuring the transmission function of distortion, designing a Volterra filter in a frequency area from the measuring result and convolution-operating the Volterra filter in the frequency area. SOLUTION: A frame division part 12 divides signals from a signal source 1 by length N while they are partially overlapped so as to take them in. The divided signal of a time area is transformed into the signal of the frequency area in a Fourier transformation part 13. N-pieces of first coefficients in the frequency area and N×N- pieces of two-dimensional second coefficients in the frequency area are stored in storage parts 15 and 17. Thus, operation based on the first coefficients and the output signal of the Fourier transformatiout part 13 and operation based on the second coefficients and the output signal of the Fourier transformation part 13 are executed in operation parts 14, 16 and 18. Consequently, distortion from the output signal of the Fourier transformation part is removed. An inverse Fourier transformation part 19 transforms the output signals of the operation parts 14, 16 and 18 into the signals of the time area, and a frame synthesis part 20 sequentially connects a part of the output signals of the inverse Fourier transformation part 19 and outputs them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion removing apparatus for removing harmonic distortion and cross-modulation distortion occurring in a non-linear system such as a speaker for reproducing an audio signal and reproducing the input signal with high fidelity. The present invention relates to a coefficient determining method of a removing apparatus, a processing speaker system, a multiprocessor, and an amplifier.

[0002]

2. Description of the Related Art As is well known, when music or announcements are reproduced in a large space such as a concert hall, an outdoor theater, or a stadium, a large commercial speaker system capable of reproducing a large volume is generally used. In particular, a horn loudspeaker system is used for reproduction of a high frequency range, and a speaker called a woofer or a sub woofer is used for reproduction of a low frequency range.

A horn speaker system is composed of a compression driver, which is an electroacoustic transducer, and a horn to which sound waves output from the compression driver are input. The compression driver converts the input electric signal into a sound wave and inputs the sound wave to the horn, and the horn radiates the sound wave to a large space. In the compression driver, the sound pressure radiated from the diaphragm is increased by making the diameter of the portion connected to the horn (the throat portion of the horn) smaller than the diameter of the diaphragm that generates sound waves. Thereby, high-volume reproduction becomes possible.

[0004] However, in the compression driver, when the air is highly compressed, the reproduced sound is distorted, and this distortion is added to the original sound wave. This is one of the causes of distortion that occurs when a large volume is reproduced by a horn speaker system, and is very important.

On the other hand, when a bass is reproduced at a large volume by a woofer, the diaphragm of the woofer is vibrated with a large amplitude. However, the reproduced sound is distorted due to the mechanical non-linearity of the damper and the edge supporting the diaphragm and the non-linearity of the excluded volume of air due to the edge.

[0006] The above-mentioned distortions are non-linear distortions called harmonic distortion and cross-modulation distortion. When a sound is reproduced at a large volume, these nonlinear distortions are generated for the above-described reasons and the like, and these nonlinear distortions cause deterioration of sound quality.

[0007]

As a means for removing distortion of a system that generates nonlinear distortion such as a speaker (hereinafter referred to as a nonlinear system), there is a method of using a nonlinear filter. As a method for removing distortion of a general nonlinear system, a Volterra filter is famous. In general, a one-dimensional filter, a two-dimensional filter,..., An n-dimensional filter are connected in parallel, a convolution operation is performed on an input signal in each filter, and the results are added and output. It is to do.

However, this filter is a two-dimensional filter, from a three-dimensional filter to an n-dimensional filter.
There is a problem that the amount of calculation increases enormously as the order increases. For example, even when a speaker is regarded as a non-linear system and only a second-order distortion is removed, a large-scale apparatus is required to perform a two-dimensional convolution operation on an audio signal as an input signal in real time. .

US Patent 4,709,391 (Arrangement for conv
erting an electric signal into an acoustic signal
or vice versa and a non-linear network for use in
Thearrangement, inventor Kaizer et al., Philips) and European Patent EP 0 168 078 A1 (same as the inventor) propose a non-linear circuit that corrects for non-linear distortions called second and third order distortions of electro-acoustic transducers. I have. According to this method, the magnetic flux density of the speaker's magnetic circuit, the inductance of the voice coil, and the nonlinearity of the spring constant of the damper are modeled by an equivalent circuit of an electric circuit, and the respective constants are obtained. Volterra series in the form of parallel connection of nonlinear distortion characteristics
ies), a nonlinear filter that can obtain the same effect as a Volterra filter is designed as a distortion correction circuit connected to the previous stage of the speaker, and a distortion compensation signal that cancels the speaker distortion by the nonlinear filter is output to the audio system. A signal is sent to a speaker in addition to the signal.

According to this method, the same distortion removing effect can be obtained without performing the two-dimensional convolution operation and the three-dimensional convolution operation in the Volterra filter.

However, in this method, it takes a considerable amount of time to measure the constants that determine the nonlinear transfer characteristics of the speaker, such as the measurement of the magnetic flux density and the inductance and the spring constant. Also, even if the measurement is performed with great effort, if any of the measurement results includes a relatively large error and the distortion correction by the above procedure does not provide much effect, the original Identifying which of the constants contains the error is difficult and requires experience.

Further, according to this method, it is possible to design a distortion correction circuit in a system in which nonlinear distortion is to be removed, such as in the case of removing distortion of an electrodynamic loudspeaker, if the cause of the distortion is clear. However, if the generation of distortion in a general nonlinear system cannot be modeled by an equivalent circuit, the circuit cannot be designed.

US Pat. No. 5,438,625 (ARRANGEMENT TO CORRE
CT THE LINEAR AND NONLINEAR TRANSFER BEHAVIOR OR E
LECTRO-ACOUSTICAL TRANSDUCERS, Inventor: W. Klippe
l, Assignee: JBL) and European Patent DE 41 11 884 C2
(Same as the inventor) has proposed a non-linear circuit for removing non-linear distortion of an electroacoustic transducer and a method for automatically updating coefficients of the circuit. Similar to the above-described conventional method, in this method, several factors of the nonlinear distortion of the loudspeaker are respectively formulated, and a nonlinear circuit serving as a nonlinear inverse system is designed. Here, the concept of the Volterra filter is used as a basis. However, the actual distortion removal circuit is not configured to perform a convolution operation of two or more dimensions, and is constructed as a non-linear circuit capable of obtaining an equivalent effect.

However, also in this method, in order to design a distortion removing circuit, it is necessary to formulate several factors of the occurrence of distortion of a speaker which is a nonlinear system. This requires that the mechanism of strain generation be known in advance. Also, after formulation, it is necessary to measure the constants and the like of these formulas, which is a rather complicated task.

As described above, the above two methods have to formulate the mechanism of distortion generation of a nonlinear system from which distortion is to be removed. Therefore, when the cause of distortion is not clear or cannot be formulated with high accuracy. Was not applicable.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and is provided at a stage prior to a non-linear system such as a loudspeaker which generates non-linear distortion, and generates a signal for compensating the above-mentioned distortion generated from the system. With the aim of providing practical and high-precision,
Furthermore, the coefficient determination method of the distortion removing device, or
An object of the present invention is to provide a processing speaker system, a multiprocessor, and an amplifier equipped with the distortion removing device.

It is another object of the present invention to provide some configurations for reducing the amount of calculation for signal processing in the distortion removing apparatus.

[0018]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is connected between a signal source and a signal input section of the system, and the system outputs a signal from the signal source. A distortion removing apparatus of the system for performing signal processing for compensating a generated distortion component, wherein the frame dividing unit divides a signal output from a signal source by a length N while partially overlapping the frame, and acquires the frame. A Fourier transform unit for performing a Fourier transform on the time domain signal divided by the dividing unit to convert the signal into a frequency domain signal;
Storage unit for storing the first coefficients and N × N second coefficients, an operation based on the first coefficient and the output signal of the Fourier transform unit, and the second coefficient and the Fourier transform An arithmetic unit that removes a distortion component from an output signal of the Fourier transform unit by performing an arithmetic operation based on an output signal of the arithmetic unit, and an inverse Fourier that performs an inverse Fourier transform of the output signal of the arithmetic unit and converts the output signal into a time-domain signal. A conversion unit; and a frame synthesizing unit for sequentially connecting and outputting a part of the output signal of the inverse Fourier transform unit.

Further, according to the present invention, there is provided the signal processing apparatus, which is connected between a signal source and a signal input unit of the system and performs signal processing for compensating for a distortion component generated in the system on a signal output from the signal source. What is claimed is: 1. A distortion removing device for a system, comprising: a frame dividing unit that divides and outputs a signal output from a signal source by a length N while partially overlapping, and Fourier transforms a time-domain signal divided by the frame dividing unit. A Fourier transform unit for transforming the signal into a signal in the frequency domain, a first storage unit for storing N first coefficients in the frequency domain, and an output signal of the first coefficient and the Fourier transform unit. A first multiplier for multiplying the first term on the right side of (Equation 1) by using:

[0020]

(Equation 35)

(Where m, m1 and m2 are integer values representing the number of points on the discretized frequency axis, and W (m) is the m-th frequency point of the output signal of the distortion removal apparatus in the frequency domain. The component, G1 (m), is the first coefficient, X
(M) is an m component of a signal obtained by transforming an input signal into a frequency domain by Fourier transform after discretization, and G2 (m1, m
2) is a second coefficient, X (m1) is an m1 component of a signal obtained by transforming an input signal into a frequency domain by Fourier transform, and X (m2) is a frequency domain by Fourier transform after discretizing the input signal. Represents the m2 component of the converted signal. Using the second storage unit that stores N × N second coefficients in the frequency domain, and the second coefficient and the output signal of the Fourier transform unit, the second term on the right side of (Equation 1) Multiplying and adding, multiplying and adding, an adder for adding an output signal of the first multiplier and an output signal of the multiplying adder, and an inverse Fourier transform of the output signal of the adder in a time domain And a frame synthesizing unit for sequentially connecting and outputting a part of the output signal of the inverse Fourier transform unit.

Further, according to the present invention, there is provided the present invention, which is connected between a signal source and a signal input section of the system, and performs signal processing for compensating for a distortion component generated in the system on a signal output from the signal source. What is claimed is: 1. A distortion removing device for a system, comprising: a frame dividing unit that divides and outputs a signal output from a signal source by a length N while partially overlapping, and Fourier transforms a time-domain signal divided by the frame dividing unit. A Fourier transform unit for converting the signal into a signal in the frequency domain, and a Fourier transform unit for Fourier transforming the impulse response of the N-tap delay unit having a delay amount substantially equal to the group delay amount of the primary impulse response of the system from which distortion is to be removed. A third storage unit that stores frequency domain taps obtained by the conversion, and reads out the taps stored in the third storage unit, and reads out the taps of the Fourier transform unit. A first multiplier that performs multiplication with a force signal, a first storage unit that stores N first coefficients in a frequency domain, and the first coefficient and an output signal of the first multiplier. A second multiplier for multiplying the first term on the right side of (Equation 1) by using

[0023]

[Equation 36]

(Where m, m1 and m2 are integer values representing the number of discrete points on the frequency axis, and W (m) is the m-th frequency point of the output signal of the distortion removal apparatus in the frequency domain. The component, G1 (m), is the first coefficient, X
(M) is an m component of a signal obtained by transforming an input signal into a frequency domain by Fourier transform after discretization, and G2 (m1, m
2) is a second coefficient, X (m1) is an m1 component of a signal obtained by transforming an input signal into a frequency domain by Fourier transform, and X (m2) is a frequency domain by Fourier transform after discretizing the input signal. Represents the m2 component of the converted signal. Using the second storage unit that stores N × N second coefficients in the frequency domain, and the output signal of the first multiplier, using the second coefficient and the output signal of the first multiplier, A multiply-adder for performing multiplication and addition of two terms, an adder for adding an output signal of the second multiplier and an output signal of the multiply-adder, and an inverse Fourier transform of the output signal of the adder An inverse Fourier transform unit for converting the signal into a time domain signal and a frame synthesizing unit for sequentially connecting and outputting a part of the output signal of the inverse Fourier transform unit are provided.

In one embodiment, the second storage unit stores a two-dimensional N × N represented in the frequency domain.
Of the second coefficients, the coefficients of the area defined by (Equation 11) are stored,

[0026]

(37)

The multiplier / adder performs the operation shown in (Equation 12) using the second coefficient of only the defined area and the output signal of the Fourier transform unit.

[0028]

(38)

In the method of determining a distortion removing apparatus according to the present invention, the first coefficient G1 (m), which is a sequence of N numerical values, is obtained by calculating a transfer function of a first-order system of the system in a frequency domain. Measured as a numerical sequence of points N2, where
N2 ≦ N1 <N, and the number of points in the time domain is calculated by the inverse Fourier transform of the numerical sequence in the frequency domain.
2, a numerical sequence of length N is added to the end of the numerical sequence in the time domain, and N-N2 0 data is added to the end of the numerical sequence in the time domain. Converted into a numerical sequence of the number of points N,
In order to obtain N × N second coefficients G2 (m1, m2), a transfer function of a secondary system that generates distortion of the system is calculated in the frequency domain. It is measured as a numerical array of points N3 × N3, where N3 ≦ N1 <N, and the numerical array of the frequency domain is converted into a numerical array of points N3 × N3 in the time domain by two-dimensional inverse Fourier transform. The number of points obtained by converting and adding NN3 0 data in the row direction and the column direction to the final end of the numerical array in the time domain to form an N × N numerical array and adding the 0 data N ×
The numerical array of N is converted into a numerical array of N × N points in the frequency domain by a two-dimensional Fourier transform, and the N × N numerical array is stored in the storage unit as the second coefficient.

In one embodiment, the number of points N2 of the transfer function of the first order system of the system and the number of points N2 of the system are
The larger value of the number of points N3 on one side of the array, which is the transfer function of the following system, is equal to the tap length N1 that defines the overlap length (N1-1) of the frame in the frame division unit. N1 has a relationship of N1 = N / 2.

Further, the present invention is connected between a signal source and a signal input section of the system, adds a characteristic of a low-pass filter to a signal output from the signal source, and adds a distortion component generated in the system. A distortion removing apparatus of the system for performing a signal processing for compensating for an analog signal, wherein the analog / digital converter converts an analog signal output from a signal source into a digital signal.
A D filter, a first filter that performs a one-dimensional convolution operation on the output signal of the A / D converter, a second filter that performs a two-dimensional convolution operation on the digital signal, An adder for adding the output signal of the first filter and the output signal of the second filter; and a D / A converter for converting the output signal of the adder to an analog signal. Where m1 and m2 are integer values representing the number of points on the frequency axis, and m = m1 + m2 with respect to the integer value m.
Or a value satisfying m = | m1-m2 |
(M) is a value expressing the transfer characteristic of the first-order system of the system in the frequency domain, and H2 (m1, m2) is a two-dimensional transfer characteristic of the second-order harmonic distortion and the cross-modulation distortion of the system. Assuming a value expressed in a frequency domain, a transfer characteristic G1L (m) of the first filter is a characteristic L (m) of the low-pass filter and a first-order transfer characteristic G1 that can be arbitrarily determined.
(M) is multiplied by G1 (m) L (m), and the transfer characteristic G2L (m1, m
2) is a characteristic represented by (Equation 16).

[0032]

[Equation 39]

In one embodiment, the second filter is a two-dimensional digital filter having a tap length of N × N, and the number of points on a frequency axis corresponding to a cutoff frequency of the low-pass filter is mc. Then, mc becomes N
/ 4 or less, the second filter satisfies (Equation 1)
7), substantial operations are performed on taps only in the region indicated by (Expression 18).

[0034]

(Equation 40)

[0035]

[Equation 41]

In one embodiment, the second filter is a two-dimensional digital filter having a tap length of N × N, and the number of points on the frequency axis corresponding to the cutoff frequency of the low-pass filter is mc. Then, mc becomes N
When it is larger than / 4, the second filter performs a substantial operation on taps only in the regions shown in (Equation 19) to (Equation 21).

[0037]

(Equation 42)

[0038]

[Equation 43]

[0039]

[Equation 44]

Further, according to the present invention, a signal output from the signal source is connected between the signal source and the signal input unit of the system, and the characteristic of the band-pass filter is added to the signal output from the signal source.
A distortion removing apparatus for performing a signal processing for compensating a distortion component generated in the system, wherein the apparatus removes an analog signal output from a signal source into a digital signal.
/ D converter, and 1 for the output signal of the A / D converter.
A first filter that performs a two-dimensional convolution operation on the digital signal, a second filter that performs a two-dimensional convolution operation on the digital signal, an output signal of the first filter,
And a D / A converter for converting the output signal of the adder into an analog signal, where m is an integer value representing the number of points on the frequency axis, and m1 And m2 are integer values representing the number of points on the frequency axis, and m = m1 + m with respect to the integer value m.
2 or m = | m1-m2 |
(M) is a value expressing the transfer characteristic of the first-order system of the system in the frequency domain, and H2 (m1, m2) is a two-dimensional transfer characteristic of the second-order harmonic distortion and the cross-modulation distortion of the system. Assuming that the value is expressed in the frequency domain, the transfer characteristic G1B (m) of the first filter is the first-order transfer characteristic G that can be arbitrarily determined as the characteristic B (m) of the band-pass filter.
1 (m) and the transfer characteristic G2L (m1, m) of the second filter.
2) is a characteristic represented by (Equation 24).

[0041]

[Equation 45]

In one embodiment, the second filter is a two-dimensional digital filter having a tap length of N × N, and is arranged on a frequency axis corresponding to a cutoff frequency on a high frequency side of the bandpass filter. The number of points is mch,
Assuming that the number of points on the frequency axis corresponding to the cutoff frequency on the lower band side of the bandpass filter is mcl, m
When ch is equal to or smaller than N / 4, the second filter performs a substantial operation on taps only in the regions indicated by (Equation 25) and (Equation 26).

[0043]

[Equation 46]

[0044]

[Equation 47]

In one embodiment, the second filter is a two-dimensional digital filter having a tap length of N × N, and is arranged on a frequency axis corresponding to a cut-off frequency on a high frequency side of the band-pass filter. The number of points is mch,
Assuming that the number of points on the frequency axis corresponding to the cutoff frequency on the lower band side of the bandpass filter is mcl, m
When ch is larger than N / 4, the second filter performs a substantial operation on taps only in the regions indicated by (Equation 27) to (Equation 29).

[0046]

[Equation 48]

[0047]

[Equation 49]

[0048]

[Equation 50]

Further, the present invention is connected between a signal source and a signal input section of the system, adds a characteristic of a high-pass filter to a signal output from the signal source, and adds a distortion component generated in the system. A distortion removing apparatus of the system for performing a signal processing for compensating for an analog signal, wherein the analog / digital converter converts an analog signal output from a signal source into a digital signal.
A D filter, a first filter that performs a one-dimensional convolution operation on the output signal of the A / D converter, a second filter that performs a two-dimensional convolution operation on the digital signal, An output signal of the first filter;
And a D / A converter for converting the output signal of the adder into an analog signal, where m is an integer value representing the number of points on the frequency axis, and m1 And m2 are integer values representing the number of points on the frequency axis, and a value satisfying m = m1 + m2 or m = | m1-m2 | with respect to the integer value m, H1 (m)
Is the value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is 2
Assuming that the transfer characteristics of the next harmonic distortion and the cross-modulation distortion are values expressed in a two-dimensional frequency domain, the transfer characteristics G1F (m) of the first filter are arbitrarily different from the characteristics F (m) of the high-pass filter. Primary transfer characteristics G1 (m) that can be determined
And the transfer characteristic G2H (m1, m2) of the second filter is:
This is a characteristic represented by (Equation 32).

[0050]

(Equation 51)

In one embodiment, the second filter is a two-dimensional digital filter having a tap length of N × N, and the number of points on a frequency axis corresponding to a cutoff frequency of the high-pass filter is mc. Then, the second
Filter performs a substantial operation on taps only in the regions indicated by (Equation 33) to (Equation 35).

[0052]

(Equation 52)

[0053]

(Equation 53)

[0054]

(Equation 54)

The present invention also relates to a system connected between a signal source and a signal input section of the system, wherein the system performs signal processing for compensating a signal output from the signal source for a distortion component generated in the system. A first filter that performs a one-dimensional convolution operation on a signal from the signal source, and a second filter that performs a two-dimensional convolution operation on a signal from the signal source A low-pass filter to which an output signal of the second filter is input;
An adder that adds the output signal of the first filter and the output signal of the low-pass filter, wherein a cut-off frequency of the low-pass filter is a frequency equal to or lower than a reproduction frequency band upper limit of the system.

The present invention also relates to a system connected between a signal source and a signal input unit of the system, wherein the system performs signal processing for compensating a signal output from the signal source for a distortion component generated in the system. A first filter that performs a one-dimensional convolution operation on a signal from the signal source, and a second filter that performs a two-dimensional convolution operation on a signal from the signal source And an adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value representing an input signal from the signal source in a frequency domain is defined as X (m). , M is an integer value representing a frequency point, and m1 and m2 are m = m1 + m2 or m = | m1-
m2 | is satisfied, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H1 (m) is defined as H1 (m).
2 (m1, m2) is a value expressing the transfer characteristic of the second-order harmonic distortion and cross-modulation distortion of the system in a two-dimensional frequency domain, and G1 (m) is the transfer characteristic of the first filter as a frequency. G2 (m1, m2)
Is a value expressing the transfer characteristic of the second filter in a frequency domain, and mc is an integer value corresponding to a cutoff frequency on a higher frequency side of a transfer characteristic of a primary system of the system.
The second filter is a two-dimensional digital filter having a tap length N × N, wherein a transfer characteristic G2 (m1, m2) for the input signal X (m) is a characteristic represented by (Equation 9), and The convolution operation of the input signal X (m) is performed only in the region represented by (Equation 36), and the resultant is output.
Areas other than (Equation 36) are blocked.

[0057]

[Equation 55]

[0058]

[Equation 56]

In one embodiment, the second filter performs the convolution operation substantially only in the region represented by (Expression 37).

[0060]

[Equation 57]

In one embodiment, when setting the one-dimensional tap of the first filter and the two-dimensional tap of the second filter, the transfer characteristic H1 (m ) And the transfer characteristic H2 of the second order system
The transfer function is measured only in the region represented by (Equation 38) in the component (m1, m2).

[0062]

[Equation 58]

The present invention also relates to a system connected between a signal source and a signal input unit of the system, wherein the system performs signal processing for compensating a signal output from the signal source for a distortion component generated in the system. A first filter that performs a one-dimensional convolution operation on a signal from the signal source, and a second filter that performs a two-dimensional convolution operation on a signal from the signal source And a band-pass filter to which an output signal of the second filter is input, and an adder for adding an output signal of the first filter and an output signal of the band-pass filter. The lower cut-off frequency of the frequency is equal to or higher than the reproduction frequency band lower limit of the system,
The high-pass cutoff frequency of the bandpass filter is
The frequency is equal to or lower than the upper limit of the reproduction frequency band of the system.

The present invention also relates to a system connected between a signal source and a signal input unit of a system, wherein the system performs signal processing for compensating a signal output from the signal source for a distortion component generated in the system. A first filter that performs a one-dimensional convolution operation on a signal from the signal source, and a second filter that performs a two-dimensional convolution operation on a signal from the signal source And an adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value representing an input signal from the signal source in a frequency domain is defined as X (m). , M is an integer value representing a frequency point, and m1 and m2 are m = m1 + m2 or m = | m1-
m2 | is satisfied, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H1 (m) is defined as H1 (m).
2 (m1, m2) is a value expressing the transfer characteristic of the second-order harmonic distortion and cross-modulation distortion of the system in a two-dimensional frequency domain, and G1 (m) is the transfer characteristic of the first filter as a frequency. G2 (m1, m2)
Is a value expressing the transfer characteristic of the second filter in a frequency domain, and mc is an integer value corresponding to a cutoff frequency on a higher frequency side of a transfer characteristic of a primary system of the system.
The second filter is a two-dimensional digital filter having a tap length N × N, wherein a transfer characteristic G2 (m1, m2) for the input signal X (m) is a characteristic represented by (Equation 9), and The input signal X (m) is convolution-operated and output only in the region represented by (Expression 39), and is output.
Areas other than (Equation 39) are blocked.

[0065]

[Equation 59]

[0066]

[Equation 60]

In one embodiment, the second filter performs a substantially convolution operation only in the region represented by (Expression 40).

[0068]

[Equation 61]

In one embodiment, when setting the one-dimensional tap of the first filter and the two-dimensional tap of the second filter, the transfer characteristic H1 (m ) And the transfer characteristic H2 of the second order system
The transfer function is measured only in the region represented by (Equation 41) in the component (m1, m2).

[0070]

(Equation 62)

The present invention is also directed to a system connected between a signal source and a signal input section of the system, wherein the system performs signal processing for compensating for a distortion component generated in the system with respect to a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source, and a second filter that performs a two-dimensional convolution operation on a signal from the signal source A high-pass filter to which an output signal of the second filter is input;
An adder for adding the output signal of the first filter and the output signal of the high-pass filter, wherein a cut-off frequency of the high-pass filter is a frequency mc equal to or higher than a lower limit of a reproduction frequency band of the system.

The present invention is also directed to a system connected between a signal source and a signal input section of the system, wherein the system performs signal processing for compensating a signal output from the signal source for a distortion component generated in the system. A first filter that performs a one-dimensional convolution operation on a signal from the signal source, and a second filter that performs a two-dimensional convolution operation on a signal from the signal source And an adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value representing an input signal from the signal source in a frequency domain is defined as X (m). , M is an integer value representing a frequency point, and m1 and m2 are m = m1 + m2 or m = | m1-
m2 | is satisfied, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H1 (m) is defined as H1 (m).
2 (m1, m2) is a value expressing the transfer characteristic of the second-order harmonic distortion and cross-modulation distortion of the system in a two-dimensional frequency domain, and G1 (m) is the transfer characteristic of the first filter as a frequency. G2 (m1, m2)
Is a value expressing the transfer characteristic of the second filter in a frequency domain, and mc is an integer value corresponding to a cutoff frequency on a higher frequency side of a transfer characteristic of a primary system of the system.
The second filter is a two-dimensional digital filter having a tap length N × N, wherein a transfer characteristic G2 (m1, m2) for the input signal X (m) is a characteristic represented by (Equation 9), and The input signal X (m) is convolution-operated and output only in the region represented by (Equation 42), and
Areas other than (Equation 42) are blocked.

[0073]

[Equation 63]

[0074]

[Equation 64]

In one embodiment, the second filter performs a substantially convolution operation only in the region represented by (Equation 43).

[0076]

[Equation 65]

In one embodiment, when the one-dimensional tap of the first filter and the two-dimensional tap of the second filter are set, the transfer characteristic H1 (m ) And the transfer characteristic H2 of the second order system
The transfer function is measured only in the region represented by (Equation 44) in the component (m1, m2).

[0078]

[Equation 66]

Further, the present invention provides a distortion removing apparatus which is provided between a signal source and a signal input unit of the processor and which performs a signal processing for compensating for a distortion component generated in the system. A first filter for performing a one-dimensional convolution operation on the signal from the signal source; a second filter for performing a two-dimensional convolution operation on the signal from the signal source; And an adder for adding the output signal of the second filter and the output signal of the second filter, wherein a value expressing the input signal from the signal source in the frequency domain is X (m), and m is the frequency. Integer values representing points, and m1 and m2 are the integer values m
, M = m1 + m2 or m = | m1-m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1,
m2) is a value expressing the transfer characteristic of the second harmonic distortion and the intermodulation distortion of the system in a two-dimensional frequency domain, E (m) is a value expressing the transfer characteristic of the processor in the frequency domain, G1 (m) is a value expressing the transfer characteristic of the first filter in the frequency domain, and G2 (m1,
Assuming that m2) is a value expressing the transfer characteristic of the second filter in the frequency domain, the second filter is a two-dimensional digital filter having a tap length N × N.
8) represented by a two-dimensional transfer characteristic G2 (m1,
In m2), the input signal X (m) is convoluted and output.

[0080]

[Equation 67]

In one embodiment, the detection unit for detecting the transfer characteristic E (m) of the processor and the detected transfer characteristic E (m) are used to determine the transfer characteristic G2 (m1 , M2) are further provided.

Further, according to the present invention, a processor is provided in a preceding stage of a system, and is inserted between a signal source and a signal input unit of the processor to perform signal processing for compensating distortion components generated in the system and the processor. A first filter for performing a one-dimensional convolution operation on a signal from the signal source; a second filter for performing a two-dimensional convolution operation on a signal from the signal source;
An adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value expressing an input signal from the signal source in a frequency domain is X (m), and m Is an integer value representing a frequency point, m1 and m2 are values satisfying m = m1 + m2 or m = | m1-m2 | with respect to the integer value m, and H1 (m) is a primary system of the system. H2 (m1, m2) is the value expressing the transfer characteristic of the second-order harmonic distortion and the intermodulation distortion of the system in the two-dimensional frequency domain, and A1 (m ) Is a value expressing the transfer characteristic of the primary system of the processor in the frequency domain,
A2 (m1, m2) is a value expressing the transfer characteristic of the secondary system of the processor in the frequency domain, G1 (m) is a value expressing the transfer characteristic of the first filter in the frequency domain, and G2 ( If m1, m2) is a value expressing the transfer characteristic of the second filter in the frequency domain, the second filter is a two-dimensional digital filter having a tap length of N × N. The input signal X (m) is convoluted with the two-dimensional transfer characteristic G2 (m1, m2) and output.

[0083]

[Equation 68]

In one embodiment, a detection unit for detecting the transfer characteristic A1 (m) of the processor and a transfer characteristic A2 (m1, m
A storage unit that stores 2), and a tap update unit that receives an output signal of the detection unit and an output signal from the storage unit and updates a transfer characteristic G2 (m1, m2) of the second filter. Is further provided.

Further, the present invention is a processing speaker system equipped with the above-described distortion removing device, wherein the system for generating the distortion is a speaker for reproducing an audio signal.

The present invention also relates to a multiprocessor equipped with the above-described distortion removing device, wherein the system for generating the distortion is a speaker for reproducing an audio signal, and the multiprocessor drives a signal source and the speaker. Inserted between amplifiers.

The present invention also relates to an amplifier equipped with the above-mentioned distortion removing device, wherein the system for generating the distortion is a speaker for reproducing an audio signal, and the amplifier drives the speaker.

In brief, the present invention constructed as described above will be briefly described. In order to remove distortion, characteristics of distortion generated from a speaker are measured in advance, and a distortion compensation signal is generated based on the measured result. Is calculated, and this coefficient is stored in the distortion removing device. The distortion removing device sequentially generates a distortion compensation signal of the speaker using the coefficient with respect to the input audio signal, adds the signal to the original audio signal, and outputs the signal to the power amplifier. This signal is input to the speaker via the power amplifier. Therefore, the distortion that has conventionally occurred is canceled by the distortion compensation signal, and only the audio signal originally output from the sound source is radiated from the speaker. As a result,
In a speaker, it is possible to reproduce an audio signal with high fidelity without generating nonlinear distortion.

Further, according to the present invention, it is possible to save the trouble of analyzing in detail the cause of distortion in a non-linear system which generates distortion, for example, a speaker.

Further, according to the present invention, a distortion compensation signal can be generated in real time for an arbitrary input audio signal.

Further, according to the present invention, it is possible to have a band limiting filter function of allowing only an input audio signal to pass through a signal of a certain frequency band and outputting the signal.

Further, according to the present invention, in the distortion removing device having the function of the band limiting filter, the amount of calculation of the two-dimensional filter can be reduced.

Further, according to the present invention, even when a graphic equalizer is connected to the subsequent stage of the distortion removing device, the distortion of the speaker can be removed.

Further, according to the present invention, when a power amplifier for driving a speaker generates non-linear distortion, distortion of the amplifier can also be removed.

[0095]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a block diagram showing a first embodiment of the present invention. The first embodiment provides a configuration and an operation method of a distortion removing apparatus that can reduce distortion of a system that generates nonlinear distortion even if the cause of the distortion is not clear. This distortion removing device 10 has an A / D converter 11 to which a signal output from the signal source 1 is input, and a relationship between N and N1 is N>
N1 and the output signal of the A / D converter is N-N1
Frame dividing device 1 that divides and takes in length N for each +1 unit
And 2. Further, a Fourier transform device 13 for Fourier transforming the signal divided by the frame dividing device 12
And a first storage device 15 for storing a first coefficient of a one-dimensional digital filter having a tap length N in a frequency domain.
And a multiplier 14 for multiplying the first term of (Equation 1) using the first coefficient and the output signal of the Fourier transform device 13.

[0097]

[Equation 69]

Further, the distortion removing device 10 comprises a second storage device 17 for storing a second coefficient which is a two-dimensional array N × N in the frequency domain, a second coefficient and the Fourier transform device 13 A multiplier / adder 16 for performing a multiplication / addition of the second term of (Equation 1) using the output signal of
And an adder 18 for adding the output signal of the multiplier 16 to the output signal of the multiplier 16. Further, an inverse Fourier transform device 19 for performing an inverse Fourier transform on the output signal of the adder 18
And a frame synthesizing device 20 for sequentially connecting and outputting the N1-th to N-th data of the output signal of the inverse Fourier transforming device 19, and D for converting the output signal of the frame synthesizing device 20 into an analog signal. / A conversion device 21.

The distortion removing apparatus 10 removes distortion of a general nonlinear system that generates second-order distortion. Here, the second-order distortion is a second-order nonlinear distortion constituted by harmonic distortion and cross-modulation distortion.

The nonlinear system is, for example, a speaker 22.

Here, the distortion generated in the speaker 22 will be described.

When the non-linear system is the speaker 22, the signal source 1 is a sound source such as a CD player, and the signal output from the sound source is a time-domain audio signal. When an audio signal of a frequency m is input to a speaker, harmonic distortion of a frequency of 2 m is generated and reproduced together with the signal of the frequency m. When two signals of frequencies m1 and m2 are input, the frequency (m1 + m2) and | m1
−m2 | is generated and reproduced together with the signals of the frequency m1 and the frequency m2.

Now, the distortion removing apparatus 10 having the above-described configuration will be described.
In FIG. 1, when an analog audio signal x (t) is input from the CD player or the like via an audio amplifier to the distortion removing apparatus 10, the A / D converter 11 outputs x (t).
To a digital signal x (n). As shown in FIG. 2A and FIG. 2B, the frame division device 12 sets the length from the last of the signal x (n) every time N−N1 + 1 output signals x (n) from the A / D converter 11 are input. Then, a frame of N is cut out and output. Therefore, N1 from the beginning of the frame
-1 data is N1-from the end of the immediately preceding frame.
It overlaps with one data part and is the same data.
Here, N> N1. The signal of length N divided as the i-th frame is input to the Fourier transformer 13 and converted into a frequency domain signal Xi (m).
m is an integer value representing the number of points on the frequency axis discretized, and corresponds to the frequency.

For the signal Xi (m), a multiplier 14,
First storage device 15, multiplier / adder 16, second storage device 1
7. The arithmetic processing shown in (Equation 2) is performed by the adder 18, and the signal Wi (m) is derived.

[0105]

[Equation 70]

The operation of (Equation 2) will be described in detail. The multiplier 14 multiplies the first coefficient G1 of the tap length N stored in the first storage device 15 by the output signal Xi (m) of the Fourier transform device 13 for each m. This is the first term in (Equation 2). On the other hand, the multiplying / adding unit 16 includes a second coefficient G2 (m1, m2), which is an N × N two-dimensional array stored in the second storage device 17, a signal Xi (m1), and a signal Xi (m2). ) Is used to calculate the second term of (Equation 2). m1 and m2 each represent a certain integer value corresponding to the frequency. The second term in (Equation 2) means that all combinations of m1 and m2 satisfying m = m1 + m2 or m = | m1-m2 | are added. For example, if m corresponds to a frequency of 5 kHz, the combination of m1 and m2 is (1 + 4) k
Hz, (2 + 3) kHz, | 7-2 | kHz, etc., and there are N combinations at maximum.

Next, the adder 18 adds the output signal of the multiplier 14 and the output signal of the multiplier / adder 16 for each m, and outputs a signal Wi (m). This adder means adding the first and second terms on the right side of (Equation 2).

The output signal Wi (m) of the adder 18 is input to the inverse Fourier transform device 19, and the signal wi in the time domain is output.
(N). The frame synthesizer 20 outputs the signal w
Of the i (n), the data from the head to the N1-1st data are discarded, and wi (N1) to wi (N) are cut out.
1 (N1),... W1 (N), w2 (N1),.
Output continuously in the order of w2 (N), w3 (N1),... The D / A conversion device 21 includes the frame synthesis device 20
Is converted into an analog signal w (t) and output. The output signal w (t) of the distortion removing device is
Is input to

Next, a method of obtaining the first coefficient and the second coefficient in the distortion removing device 10 will be described. First,
When the loudspeaker 22 that generates distortion is modeled by a block diagram, the loudspeaker becomes a system 23 having a linear transfer function H1 (m).
And a non-linear second-order transfer function H2 (m
1, m2) and an adder 25. The input / output characteristics of the speaker 22 are expressed as (Equation 3) when the display in the frequency domain is performed.

[0110]

[Equation 71]

Here, the relationship between the audio signal x (t) passed through an amplifier from a CD player or the like and the output sound pressure y (t) from the speaker 22 is expressed in the frequency domain. ) Is substituted for (Equation 3) and erased to obtain (Equation 4).

[0112]

[Equation 72]

The first term in (Equation 4) is the audio signal x
(T) shows a component passing through the multiplier 14 and the system 23 of the transfer function H1 of the speaker 22. The first term in the parentheses of the second term in (Equation 4) indicates that the audio signal x (t) is
And components passing through the system 23 of the transfer function H1 (m) of the speaker 22. The second term in parentheses of the second term in (Equation 4) is a component that causes the audio signal x (t) to pass through the multiplier 14 and the system 24 of the transfer function H2 (m1, m2) representing the distortion of the speaker. Show.

The component of x (t) passing through the multiplier / adder 16 and the system 24 of the transfer function H2 representing the distortion of the loudspeaker 22 is negligible as compared with the other terms.

Now, in order to remove the distortion component of the speaker 22, the two terms in the parentheses of the second term in (Equation 4) need only be canceled and their values become zero.

First, the coefficient G1 of the first storage device 15
(M) may be determined so that the first term of (Equation 4) is equal to a desired output sound pressure output from the speaker 22. For example, if the output signal Y (m) is the audio signal X
In order to make it equal to (m), (Equation 6) is derived from (Equation 5).

[0117]

[Equation 73]

[0118]

[Equation 74]

Alternatively, as the output signal Y (m),
If the audio signal is affected by the transfer characteristic H1 (m) of the speaker 22 and it is desired to obtain a signal obtained when the audio signal is delayed by the delay unit, the following equation is used.
What is necessary is just to make the transfer function G1 of the first filter as (Equation 8).

[0120]

[Equation 75]

[0121]

[Equation 76]

Next, the coefficient G2 (m
1, m2) will be described. In order to remove distortion generated in the speaker 22, it is only necessary to cancel two terms in parentheses of the second term of (Equation 4). Therefore, assuming that the values in parentheses are equal to 0, the coefficient G2 (m1, m2) Solving for
(Equation 9).

[0123]

[Equation 77]

To determine the coefficient G2 (m1, m2),
(Equation 9) shows the first-order transfer function H1 (m) of the speaker 22.
And a transfer function H2 (m1, m
2) and the coefficient G1 (m) of the first storage device 15 determined by the above method may be substituted.

Therefore, the coefficient G1 of the first storage device 15
(M) and the coefficient G2 (m
1, m2), the distortion removing device 10
The harmonic distortion and the cross modulation distortion of the speaker 22 can be removed.

Next, the primary transfer function H1 of the speaker 22
(M) and a method of determining the transfer function H2 (m1, m2) of the second-order distortion will be described.

First-order transfer function H1 (m) of speaker 22
Can be easily obtained by actual measurement using a test signal having a frequency m, for example, a sine wave. First-order transfer function H1
The tap length N2 of (m) is the speaker 2 in the time domain.
It is sufficient if the impulse response of No. 2 is longer than a length that sufficiently converges within the tap length. This N2 is actually the speaker 22
May be measured by inputting an impulse signal to the H.sub.1 or by inversely Fourier-transforming H1 (m) obtained in the frequency domain into a time-domain waveform, and determining whether the waveform has sufficiently converged. . The tap length N2
Must be equal to or shorter than N1, which defines the overlap length (N1-1) of the frames in the frame division device 12.

The transfer function H2 of the secondary distortion of the speaker 22
(M1, m2) are test signals of frequencies m1 and m2,
For example, it can be easily obtained using a signal obtained by adding a sine wave of frequency m1 and a sine wave of frequency m2. 2
Transfer function H2 (m1, m2) of second-order distortion that is a two-dimensional array
The tap length N3 of one side is obtained by converting the H2 (m1, m2) obtained in the frequency domain into a waveform in the time domain by performing a two-dimensional inverse Fourier transform, and the two-dimensional waveform becomes N3 × N
It is sufficient that the length is longer than the length that sufficiently converges in the plane of No. The tap length N3 is N1 which defines the overlap length (N1-1) of the frame in the frame division device 12.
Must be equal to or shorter than N1.

Next, the frame length N when the audio signal is divided by the frame dividing device 12, the overlap length (N1-1), and the primary transfer function H of the speaker 22
FIGS. 2A, 2B, 2C, and 2C show the relationship between the tap length N2 of 1 (m) and the tap length N3 of one side of the array H2 (m1, m2) representing the transfer function of the secondary distortion of the speaker 22.
This will be described with reference to FIG. 2D. Here, in order to make the explanation easy to understand, it is assumed that N1, N2, and N3 are equal.

First, the first-order transfer function H1 of the speaker 22
(M) and the transfer function H2 of the second-order distortion (m1, m2)
Are measured at tap lengths N1 and N1 × N1, respectively. Then, the first coefficient G1 (m) and the second coefficient G2 (m1, m
2) is calculated. Here, the tap length of the first G1 (m) is N1, and the tap length of the second coefficient G2 (m1, m2) is N1 × N1. The operation performed by the multiplier 14 of the distortion removing apparatus 10 is essentially a one-dimensional convolution operation on the input signal. The operation performed by the multiplying / adding unit 16 is essentially a two-dimensional convolution operation.

There are several methods for performing a convolution operation on an aperiodic signal such as a general audio signal. Here, the overlap saving method (Overlap-
SaveMethod: “FAST ALGORITHMS FOR DIGITAL SIGNAL P
ROCESSING '' Chapter 9 pp.283-289 Richard E. Blahut
By 1985 ADDUSON-WESLEY PUBLISHING COMPANY
Inc.) (see Issuance of Inc.) in the frequency domain. Therefore, it is necessary to extend the first coefficient G1 (m) to the tap length N here. Also, the second coefficient G2 (m
1, m2) must be extended to a tap length N × N.

Therefore, in the present invention, in order to extend the tap length, the first coefficient G1 (m) and the second coefficient G2 (m1, m2) are transformed into the time domain. Next, as shown in FIG. 2C, (N−N1) 0 data are added to the first coefficient converted into the time domain. FIG.
As shown in D, the second coefficient converted to the time domain includes:
0 data is added. After that, the first coefficient and the second coefficient are again transformed into the frequency domain. Thereby, the first
Is extended to the tap length N, and the second coefficient is
This means that the tap length has been extended to N × N.

To summarize the above tap length, the tap length of the first coefficient G1 (m) calculated using the first-order transfer characteristic and the second-order distortion transfer characteristic of the speaker is N1, and The tap length of the second coefficient G2 (m1, m2) is N1 × N1. Next, the tap length is extended by the method described above, and the first distortion removal device 10
The tap length of the first coefficient G1 (m) stored in the storage device 15 is N, and the tap length of the second coefficient G2 (m1, m2) stored in the second storage device 17 is N. is there. A first coefficient G1 (m) and a second coefficient G2 (m1, m
2) has essentially the same characteristics before and after the extension of the tap length. Therefore, for the sake of simplicity, in this specification, the first coefficient is G1 both before and after the tap length is extended.
(M), the second coefficient is described using the symbol G2 (m1, m2).

Next, the frame length N in the frame dividing device 12 and the length N1 for defining the overlap length at the time of capturing a signal will be described.

The distortion removing apparatus of the present invention converts an input audio signal into a frequency domain for each frame, performs signal processing, converts the signal into a time domain again, and outputs the converted signal.

The amount of operation required for one signal w (n) output from the distortion removing apparatus 10 of the first embodiment will be considered. For example, the primary impulse response length N1 of the speaker
When (= N2 = N3) is set to 128 taps and the frame division length N is set to 256 taps, the distortion removing device 1
The calculation amount at 0 is the smallest. This is (Equation 1)
0).

[0137]

[Equation 78]

Next, the significance of converting the input audio signal into the frequency domain, performing signal processing, converting it again into the time domain, and outputting the converted signal as in the distortion removal apparatus of the present invention will be considered.

As a conventional method for removing distortion of a general nonlinear system, there is a method in which a convolution operation is performed only in the time domain using a one-dimensional digital filter and a two-dimensional digital filter. Since the amount of operation required for the dimensional convolution operation is enormous, a distortion removal device becomes huge for real-time processing of an input audio signal, and such a distortion removal device is not practical.

A feature of the distortion removing apparatus of the present invention is that the amount of calculation in the distortion removing apparatus can be reduced by converting an input audio signal into a frequency domain and performing an operation. Here, the number of multiplications and the number of additions required in the distortion removal apparatus of the present invention will be considered.

The number of times of multiplication and addition required in the distortion removing apparatus 10 to remove distortion of the speaker 22 is on the order of the first power of N for each digitally converted audio signal x (n). is there. On the other hand, in the conventional method using the convolution operation in the time domain, the number of times of multiplication required in the convolution operation is determined by the audio signal x (n)
Is of the order of the square of N, and the amount of calculation is very large.

Therefore, like the distortion removing device of the present invention,
By converting the input audio signal into the frequency domain to perform signal processing, and then converting it to the time domain and outputting it again, the amount of calculation is greatly reduced.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 3A, 3B, 3C and 3D.

In the second embodiment, the second storage device 1
7 and the amount of calculation in the multiplier / adder 16 can be further reduced.

The configuration of this distortion removing apparatus is almost the same as that of the first embodiment, except that the second storage device 17 of FIG. 1 stores only the coefficients of the area shown in FIG. 3A. That is good. When the area shown in FIG. 3A is expressed by a mathematical expression, it is an area defined by (Equation 11).

[0146]

[Expression 79]

In the distortion removing apparatus according to the first embodiment, the second right-hand side of (Equation 1) in the multiplier-adder 16 of the distortion removing apparatus 10 is used.
Although the multiplication and addition of the term operations occupy a large amount of the operation amount of the entire apparatus, in the second embodiment, the operation amount in the multiplication / addition unit 16 can be reduced, and the scale of the apparatus can be reduced.

The features of the second coefficient G2 (m1, m2) will be described. In the second coefficient G2 (m1, m2), the coefficient of the hatched portion in FIG.
There is a line-symmetric relationship with m2 as the axis of symmetry. FIG. 3C
The coefficients of the shaded area and other areas are (N / 2, N /
There is a conjugate relationship with 2) as the center of point symmetry. Also, the second
In the coefficient G2 (m1, m2) of
In the product-sum operation of the term, since the result of the product-sum operation always has a conjugate relationship in the shaded portion in FIG. 3D and in other portions, only the shaded portion needs to be considered in the actual calculation. Then, FIG. 3B,
When the intersection of FIGS. 3C and 3D is taken, the shaded area of FIG. 3A is obtained.
A product-sum operation may be performed on each coefficient G2 (m1, m2) in the hatched portion of A, and the results may be added as shown in (Equation 12).

[0149]

[Equation 80]

Thus, the multiplying / adding unit 16 required for one sample of the digitally converted audio signal is provided.
Is about 3/16, and the scale of the distortion removing apparatus 10 can be reduced.

(Third Embodiment) FIG. 4 is a block diagram showing a distortion removing apparatus according to a third embodiment of the present invention.

The distortion removing device 40 according to the third embodiment comprises:
Although it is almost the same as that of the first embodiment, a different point is that a new second multiplier 26 is provided at the subsequent stage of the Fourier transform device 13, and the second multiplier 26 has a coefficient D1
That is, a third storage device 27 storing (m) is provided.

Impulse response h1 (t) of speaker 22
Generally has a characteristic including a group delay with respect to the input signal x (t). The transfer function H1 (m) of the first-order system of the speaker 22 is obtained by discretizing h1 (t) and performing Fourier transform. When h1 (t) has a group delay, the transfer function H1 (m) is expressed by (Equation 6). When the first coefficient G1 (m) is determined in consideration of only the frequency characteristics as performed, the distortion removing device 40
The causality of the input / output characteristics of the entire system including the speaker 22 and the speaker 22 is violated. Here, there is a problem that even if a random audio signal having no periodicity is input to the distortion removing device 40, the distortion of the speaker 22 is not removed as desired.

In the third embodiment, to solve this problem, as shown in FIG. 4, a second multiplier 26 and a coefficient D
A third storage device 27 storing 1 (m) is provided.

In the above configuration, first, the third storage device 27 stores the Fourier-transformed coefficient of the impulse response characteristic of the N-tap delay device having a delay effect substantially equivalent to the group delay amount τ of h1 (t). D1 (m) is stored.

The multiplier 26 multiplies the signal X (m) by D1 (m) read from the third storage device 27 for each m and outputs the result. Thereby, the second
Of the components passing through the multiplier 26 of the speaker 22 are delayed according to the group delay amount of the primary system of the speaker 22.
For the component passing through the multiplier / adder 16, the coefficient X1 (m1) read from the third storage device 27 is multiplied by the signal X (m1) in the second multiplier 26, and the signal X (m1) is multiplied. X (m2) is multiplied by the coefficient D1 (m2) read from the third storage device 27, and is then output to the multiply-adder 16. As a result, the output is delayed with a delay corresponding to the group delay amount of the speaker distortion. Thereby, the first multiplier 14 and the second multiplier 2
6, the relationship between the signal X (m) and the signal W (m) by the multiplier / adder 16 and the adder 18 is given by (Equation 13).

[0157]

[Equation 81]

With the above operation, the distortion removing device 40
Even when a general audio signal having no periodicity is input, distortion of the speaker 22 can be removed.

Here, from (Equation 13), G1
(M) D (m) is stored in the first storage device 15 of FIG. 1 as a new first coefficient, and G2 (m1, m2) D1 (m
1) Using D1 (m2) as a new second coefficient, the second coefficient in FIG.
It is also possible to perform equivalent distortion removal using the distortion removal device 10 of FIG.

(Fourth Embodiment) FIG. 5 shows a processing speaker system 50 according to a fourth embodiment of the present invention. This processing speaker system 50 incorporates any of the distortion removing devices 10 and 40 of the first to third embodiments, and outputs the output of the distortion removing device to the speaker 22.

Particularly, in a business field or the like, since a large volume is generated by the speaker 22, non-linear distortion is likely to occur, and the above-described distortion removing devices 10 and 40 are used.
, And performing signal processing for distortion compensation, it is possible to improve sound quality.

(Fifth Embodiment) Next, FIG. 6 shows a multiprocessor 60 according to a fifth embodiment of the present invention. The multiprocessor 60 incorporates an equalizer and a de-example circuit 61 for adjusting frequency characteristics and delay time, and one of the distortion removing devices 10 and 40 of the first to third embodiments. Is applied to the speaker 22.

In general, when an audio signal is reproduced by a commercial speaker, a signal processor called a multiprocessor is inserted between the sound source and the speaker 22 to adjust the frequency characteristics and the delay time. Therefore, by incorporating the distortion removing device of any of the first to third embodiments in the multiprocessor 60, the distortion of the speaker 22 can be removed without increasing the number of devices constituting the sound reproduction system.

(Sixth Embodiment) FIG. 7 is a block diagram showing a distortion removing apparatus according to a sixth embodiment of the present invention.

The distortion removing device 70 includes an A / D converter 11 to which an audio signal output from a sound source 1 such as a CD player is input, a frame dividing device 12, a Fourier transform device 13, and a Fourier transform device 13. , A second filter 72 to which an output signal of the Fourier transform device 13 is input, an output signal of the first filter 71 and an output of the second filter 72 It has an adder 18 for adding the signal, an inverse Fourier transform device 19 for inputting the output signal of the adder, a frame synthesizing device 20, and a D / A converting device 21.

The first filter 71 is a one-dimensional filter having the function of combining the first storage device 15 and the multiplier 14 in the distortion removing device 10 of FIG. Also, the second
The filter 72 is a two-dimensional filter having the functions of the second storage device 17 and the multiplying / adding device 16 in the distortion removing apparatus 10 of FIG.

The distortion removing device 70 according to the sixth embodiment comprises:
Transfer characteristics of first filter 71 and second filter 7
By devising the transfer characteristic of No. 2, the distortion removing device 70 also has a function of a low-pass filter, thereby eliminating the need for a low-pass filter conventionally required in a sound reproducing system and simplifying the configuration of the sound reproducing system. It is an object of the present invention to provide a device capable of removing distortion.

Here, the relationship between the input signal X (m) of the distortion removal device 70 and the output signal WL (m) of the distortion removal device 70 is expressed by a discrete expression in the frequency domain (Equation 14).
Shown in

[0169]

(Equation 82)

Transfer characteristics G1L of the first filter 71
(M) is L (m) G1 (m) containing the transfer characteristic L (m) of the low-pass filter as a component, and the transfer characteristic G2L (m1, m2) of the second filter 72 is L including transfer characteristic L (m) as a component
(M1) L (m2) G2 (m1, m2).

With this configuration, when an analog audio signal x (t) is input from the signal source 1 such as a CD player to the distortion removal device 70, the A / D conversion device 11
Converts x (t) to a digital signal x (n). A
The output signal of the / D conversion device 11 is
After being divided and converted into the frequency domain via the Fourier transform device 13, it is input to the first filter 71. Here, the first filter 71 has a transfer characteristic L
(M) G1 (m), which performs a one-dimensional convolution operation on an input signal. This is the first term on the right side of (Equation 14).

On the other hand, the output signal of the Fourier transform device 13 is also input to the second filter 72. Here, the second
Is a two-dimensional digital filter,
Two-dimensional transfer characteristic L (m1) L (m2) G2 (m1, m
According to 2), a two-dimensional convolution operation is performed on the input signal. This is the second term on the right side of (Equation 14).

The output signal of the first filter 71 and the output signal of the second filter 72 are input to the adder 18 and added. This is the addition between the first and second terms on the right side of (Equation 14).

The output signal of the adder 18 is converted into the time domain and connected via the inverse Fourier transform unit 19 and the frame synthesizing unit 20 and then the D / A converter 2
1, and after D / A conversion, the distortion removal device 70
As an output signal.

Next, a method of determining the transfer characteristics of the first filter 71 and the second filter 72 will be described.

First, the transfer characteristic of the first filter (consisting of the first storage device 15 and the multiplier 14) of the distortion removing device 10 of the first embodiment which does not have the effect of the low-pass filter is represented by G1 (m). G2 (m1, m2) as the transfer characteristic of the second filter (comprising the second storage device 17 and the multiplier / adder 16).
Then, these are obtained in the same manner as in the method in the first embodiment.

[0177] On the other hand, for example, in a commercial sound reproducing system, when a woofer that reproduces mainly sound waves in a low frequency band is used as a speaker, a signal output from a sound source such as a CD player is passed through a low-pass filter. Input to the speaker. Therefore, in the sixth embodiment, the transfer characteristics of the first filter 71 and the second filter 72 are determined as follows, so that the distortion removing device 70 also has a function of a low-pass filter, and the sound removal system This makes it possible to omit the low-pass filter.

It is assumed that the transfer characteristic of the low-pass filter is L (m). Transfer characteristic G1L (m) of the first filter 71 of the distortion removing device 70 having a function of a low-pass filter.
Is multiplied by the previously determined G1 (m) and the transfer characteristic L (m) of the low-pass filter to obtain a characteristic G1 (m) L (m)
(G1L (m) = G1 (m) L
(M)). Next, the transfer characteristic of the second filter 72 is represented by G2
Let L (m1, m2). When the relationship between the input signal X (m) of the distortion removing device 70 and the output signal Y (m) of the speaker is expressed in the frequency domain, the following expression (15) is obtained.

[0179]

[Equation 83]

In order for the distortion removing device 70 to have the function of a low-pass filter, the first and second terms in the braces of the second term on the right side of (Equation 15) need only be canceled. G2L (m1, m2) may be determined as shown in (Equation 16).

[0181]

[Equation 84]

As described above, the present invention provides the distortion removing device 70
Has a function of a low-pass filter, and can also remove distortion of the speaker 22. As a result, even if the distortion removing device 70 is inserted into the sound reproduction system, the low-pass filter that has been required so far can be deleted from the system, and the distortion of the speaker can be reduced without increasing the scale of the sound reproduction system. Can be removed.

(Seventh Embodiment) Next, a seventh embodiment of the present invention will be described with reference to FIGS. 8A and 8B.

In the seventh embodiment, the distortion removing device 70
Assuming that the second filter 72 has a function of a low-pass filter, the amount of calculation in the second filter 72 is reduced to reduce the amount of calculation of the entire distortion removing device 70.

The seventh embodiment is different from the sixth embodiment in the area of the filter tap where the second filter 72 performs the operation.

The content of the calculation in the case where the calculation in the second filter 72 is performed in the frequency domain is the second term of (Equation 15). Here, in the seventh embodiment, in consideration of the symmetry and conjugate properties of the filter taps of the second filter 72 and the low-pass filter function, the seventh embodiment substantially corresponds to the shaded region of FIG. 8A or 8B. By performing multiplication and addition only for the filter taps of the second filter 72, the number of times of multiplication and addition can be reduced.

When FIG. 8A is represented by a mathematical expression, it is an area represented by (Equation 17) and (Equation 18).

[0188]

[Equation 85]

[0189]

[Equation 86]

FIG. 8B is expressed by the following equation (Equation 19).
, (Equation 20) and (Equation 21).

[0191]

[Equation 87]

[0192]

[Equation 88]

[0193]

[Equation 89]

The first and second filters 71 and 7 are provided so that the distortion removing device 70 has the function of a low-pass filter.
When two taps are set, the output signal of the first filter 71 and the output signal of the second filter 72 are signals limited to components below the cutoff frequency of the desired low-pass filter characteristic. That is, the component above the cutoff frequency becomes very small.

In the seventh embodiment, of the multiplication and addition of the second term of (Equation 15) performed in the second filter 72, substantially only the shaded area in FIG. 8A or 8B is used. Since it suffices to perform this, it is possible to reduce the amount of calculation.

8A or 8B is determined by the relationship between the cutoff frequency of the low-pass filter and the tap length of the second filter 72. If the second filter 72 is a two-dimensional digital filter having N × N taps and a point on the frequency axis corresponding to the cutoff frequency of the low-pass filter function is mc, FIG. 8A shows the case where mc ≦ N / 4. In the case of N / 4 <mc, the multiplication and addition of the second term of (Equation 15) may be performed for the region of FIG. 8C.

As a result, the second filter 7 which has occupied a large part of the total operation amount in the distortion removing apparatus 70 up to now.
The number of times of multiplication and addition of 2 is reduced, and the distortion removal device 70
Can be considerably reduced.

(Eighth Embodiment) FIG. 9 is a block diagram showing a distortion removing apparatus according to an eighth embodiment of the present invention.

The distortion removing device 90 includes an A / D converter 11 to which an audio signal output from a sound source 1 such as a CD player is input, a frame dividing device 12, a Fourier transforming device 13, and a Fourier transforming device 13. , A second filter 92 to which an output signal of the Fourier transformer 13 is input, an output signal of the first filter 91, and an output of the second filter 92. It has an adder 18 for adding the signal, an inverse Fourier transform device 19 for inputting the output signal of the adder, a frame synthesizing device 20, and a D / A converting device 21.

The first filter 91 is a one-dimensional filter having the function of combining the first storage device 15 and the multiplier 14 in the distortion removing device 10 of FIG. Also, the second
The filter 92 is a two-dimensional filter having the functions of the second storage device 17 and the multiplying and adding device 16 in the distortion removing device 10 of FIG.

The distortion removing device 90 according to the eighth embodiment comprises:
The difference from the distortion removing device 10 of the first embodiment is as follows. When the speaker 22 whose distortion is to be removed by the distortion removing device 90 is a mid-range horn speaker, a bandpass filter is originally required between the sound source 1 such as a CD player and the speaker 22 in the sound reproducing system. . Therefore, the eighth embodiment is characterized in that the distortion removing device 90 also has a band-pass filter characteristic.

Here, the relationship between the input signal X (m) of the distortion removing device 90 and the output signal WB (m) of the distortion removing device 90 is represented by (Expression 22) by the expression in the frequency domain.

[0203]

[Equation 90]

The transfer characteristic G1B of the first filter 91
(M) is B (m) G1 (m) including the transfer characteristic B (m) of the band-pass filter as a component, and the transfer characteristic G2B (m1, m2) of the second filter 92 is B (m1) B (m2) G2 (m1, m2) containing the transfer characteristic B (m) of the filter as a component.

Next, a method for determining the transfer characteristics of the first filter 91 and the second filter 92 will be described.

The first having no bandpass filter effect
The transfer characteristic of the first filter (consisting of the first storage device 15 and the multiplier 14) in the distortion removal device 10 of the embodiment is represented by G1 (m), and the second filter (the second storage device 17).
And the transfer characteristic of the multiplier / adder 16 are represented by G2 (m1, m
If 2), these are obtained in the same manner as in the method in the first embodiment.

As described above, for example, in a sound reproducing system for business use, when a mid-range speaker that mainly reproduces a middle-range sound wave is used as the speaker 22, the sound is output from the sound source 1 such as a CD player. The resulting signal is passed through a bandpass filter and then input to the speaker 22. Therefore, the eighth
In the embodiment, the transfer characteristics of the first filter 91 and the second filter 92 are determined as follows, so that the distortion removing device 90 also has a band-pass filter function. This makes it possible to eliminate the need for vitals.

First, the transfer characteristic of the band-pass filter is represented by B
(M). Transfer characteristics G1 of the first filter 91 of the distortion removing device 90 having a band-pass filter function.
A characteristic G1 (m) obtained by multiplying B (m) by G1 (m) determined in advance and the transfer characteristic B (m) of the band-pass filter.
B (m) (G1B (m) = G1
(M) B (m)). Next, when the transfer characteristic of the second filter 92 is G2B (m1, m2) and the relationship between X (m) and Y (m) is expressed by a mathematical expression, the following expression (23) is obtained.

[0209]

[Equation 91]

In order for the distortion removing device 90 to have a band-pass filter function, the first and second terms in the curly braces of the second term on the right side of (Equation 23) need only be canceled. G2B (m1, m2) may be determined as shown in (Equation 24).

[0211]

(Equation 92)

As described above, in the eighth embodiment, the distortion removing device 90 also has the function of a band-pass filter, and removes the distortion of the speaker 22. As a result, even if the distortion removing device 90 is inserted into the sound reproducing system, the band pass filter which has been required so far can be deleted from the system, and the size of the speaker 22 can be reduced without increasing the size of the sound reproducing system.
Can be removed.

(Ninth Embodiment) Next, a ninth embodiment of the present invention will be described with reference to FIGS. 10A and 10B.

In the ninth embodiment, the distortion removing device 90
With the function of a bandpass filter
The amount of calculation in the second filter 92 is reduced, so that the amount of calculation in the entire distortion removal device 90 is reduced.

The ninth embodiment is different from the eighth embodiment in the area of the filter tap where the second filter 92 performs the operation.

The content of the calculation in the case where the calculation in the second filter 92 is performed in the frequency domain is the second term of (Equation 22). Here, considering the symmetry and conjugation of the filter taps of the second filter 92 and the band-pass filter function, the filter of the second filter 92 substantially in the shaded region of FIG. 10A or 10B is considered. By performing multiplication and addition only for taps, the number of multiplications and additions can be reduced.

When FIG. 10A is represented by a mathematical expression, it is an area represented by (Equation 25) and (Equation 26).

[0218]

[Equation 93]

[0219]

[Equation 94]

FIG. 10B is expressed by the following equation.
7), (Equation 28) and (Equation 29).

[0221]

[Equation 95]

[0222]

[Equation 96]

[0223]

(97)

First, the taps of the first and second filters 91 and 92 are set so that the distortion removing device 90 has the function of a band-pass filter.
1 and the output signal of the second filter 92 are
The signal is limited to the frequency components within the pass band of the desired band-pass filter characteristics. In other words, components below the lower cut-off frequency and components above the higher cut-off frequency are very small.

Therefore, in the ninth embodiment, of the multiplication and addition of the second term of (Equation 22) performed in the second filter 91, substantially the shaded area in FIG. 10A or 10B is used. Only needs to be performed, whereby the amount of calculation can be reduced.

Which of the shaded areas in FIG. 10A and FIG. 10B is to be operated is determined by the relationship between the cut-off frequency mch on the high frequency side of the band-pass filter and the tap length of the second filter 92. If the second filter 92 is a two-dimensional digital filter having N × N taps and a point on the frequency axis corresponding to the high-frequency cutoff frequency of the band-pass filter function is mch ≦ mch ≦
In the case of N / 4, the area of FIG.
When 4 <mch, the region of FIG.
The multiplication and addition of the second term in 2) may be performed.

As a result, the second filter 9 which has occupied a large part of the total operation amount in the distortion removing apparatus 90 up to now.
The number of multiplications and additions of 2 is reduced, and the distortion removal device 90
Can be considerably reduced.

(Tenth Embodiment) FIG. 11 is a block diagram showing a distortion removing apparatus according to a tenth embodiment of the present invention.

The distortion removing device 110 includes an A / D converter 11 to which an audio signal output from the sound source 1 such as a CD player is input, a frame dividing device 12, a Fourier transforming device 13, and a Fourier transforming device 13. And the second filter 112 to which the output signal of the Fourier transformer 13 is input.
An adder 18 for adding an output signal of the first filter 111 and an output signal of the second filter 112;
Inverse Fourier transform device 1 for inputting the output signal of the adder
9, a frame synthesizing device 20, and a D / A converter 21.

The first filter 111 is a one-dimensional filter having the function of combining the first storage device 15 and the multiplier 14 in the distortion removing device 10 of FIG. The second filter 112 is a two-dimensional filter having the functions of the second storage device 17 and the multiplier / adder 16 in the distortion removing device 10 of FIG.

The distortion removing device 110 according to the tenth embodiment is used.
Is different from the distortion removing device 10 of the first embodiment in the following points. When the speaker 22 whose distortion is to be removed by the distortion removing device 110 is a high-frequency horn speaker,
In the sound reproduction system, a high-pass filter is required between the sound source 1 such as a CD player and the speaker 22. Therefore, the tenth embodiment is characterized in that the distortion removing device 110 also has a high-pass filter characteristic.

Here, the relationship between the input signal X (m) of the distortion removing device 110 and the output signal WF (m) of the distortion removing device 110 is expressed by a discrete expression in the frequency domain (Equation 3).
0).

[0233]

[Equation 98]

The transfer characteristic G1 of the first filter 111
F (m) is F (m) G1 (m) containing the transfer characteristic F (m) of the high-pass filter as a component, and the transfer characteristic G2F (m1, m2) of the second filter 112 is a high-pass filter. F (m1) F (m2) G2 (m1, m2) including the transfer characteristic F (m) of the above as a component.

Next, a method for determining the transfer characteristics of the first filter 111 and the second filter 112 will be described.

The first filter (first storage device 1) in the distortion removing apparatus 10 having no high-pass filter effect is used.
Assuming that the transfer characteristic of the second filter (comprising the second storage device 17 and the multiplying adder 16) is G2 (m1, m2), the transfer characteristic of the second filter (consisting of the multiplier 5 and the multiplier 14) is G1 (m). Is obtained in the same manner as in the first embodiment.

As described above, for example, in a general-purpose audio reproduction system, when a high-frequency speaker that mainly reproduces high-frequency sound waves is used as a speaker, the sound is output from the sound source 1 such as a CD player. The signal passes through a high-pass filter before being input to the speaker 22. Accordingly, in the tenth embodiment, the transfer characteristics of the first filter 111 and the second filter 112 are determined as follows, so that the distortion removing device 110 also has a function of a high-pass filter, and the This eliminates the need for a high-pass filter.

First, the transfer characteristic of the high-pass filter is expressed by F
(M). Transfer characteristic G of the first filter 111 of the distortion removing device 110 having a function of a high-pass filter.
1F (m) is multiplied by G1 (m) determined earlier and the transfer characteristic F (m) of the band-pass filter.
(M) Make it equal to F (m) (G1F (m)
= G1 (m) F (m)). Next, the second filter 112
Is defined as G2F (m1, m2), X (m) and Y
When the relationship of (m) is expressed by a mathematical expression, it is (Equation 31).

[0239]

[Equation 99]

In order for the distortion removing device 110 to have a band-pass filter function, the first and second terms in the curly braces in the second term on the right side of (Equation 31) need only be canceled. G2F (m1, m2) may be determined as shown in (Equation 32).

[0241]

[Equation 100]

As described above, in the tenth embodiment, the distortion removing device 110 is also provided with a function of a high-pass filter so that the distortion of the speaker 22 can be removed. Thereby, even if the distortion removal device 110 is inserted into the sound reproduction system,
The high-pass filter which has been required until then can be deleted from the system, and the distortion of the speaker can be removed without increasing the scale of the sound reproduction system.

(Eleventh Embodiment) Next, the eleventh embodiment of the present invention will be described.
An embodiment will be described with reference to FIG.

In the eleventh embodiment, the distortion removing device 1
Assuming that the filter 10 has a function of a high-pass filter, the calculation amount of the second filter 112 is reduced to reduce the calculation amount of the entire distortion removal device 110.

The eleventh embodiment differs from the tenth embodiment in the area of the filter tap where the second filter 112 performs the operation.

The content of the calculation when the calculation in the second filter 112 is performed in the frequency domain is the second term of (Equation 30). Here, considering the symmetry and conjugation of the filter taps of the second filter 112 and the high-pass filter function, the second portion of the region substantially shaded in FIG.
By performing multiplication and addition only for the taps of the filter 112, the number of times of multiplication and addition can be reduced.

When FIG. 12 is represented by a mathematical expression, it is an area represented by (Equation 33), (Equation 34), and (Equation 35).

[0248]

[Equation 101]

[0249]

[Equation 102]

[0250]

[Equation 103]

First, when the taps 111 and 112 of the first and second filters are set so that the distortion removing device 110 has the function of a high-pass filter, the output signal of the first filter 111 and the output signal of the second filter 112 are set. The output signal is a signal limited to components below the cutoff frequency of the desired high-pass filter characteristic. That is, components below the cut-off frequency are very small.

Therefore, in the eleventh embodiment, the second
Of the multiplication and addition of the second term in (Equation 30) performed by the filter 112, it is sufficient to substantially perform the addition only on the area indicated by the hatched portion in FIG. 12, whereby the calculation amount can be reduced. Become.

As a result, the distortion removing device 110
Can reduce the number of times of multiplication and addition of the second filter 112, which has occupied a large part of the total operation amount, and can considerably reduce the total operation amount in the distortion removing apparatus.

Note that the distortion removing devices 70, 90, and 110 of the sixth to eleventh embodiments are the same as the distortion removing device 1 in the processing speaker system 50 of the fourth embodiment.
It may be applied instead of 0 and 40, or may be applied instead of the distortion removal devices 10 and 40 in the multiprocessor 60 of the fifth embodiment.

In the distortion removing devices 70, 90, and 110 of the sixth to eleventh embodiments, the audio signal output from the sound source 1 is converted into a signal in the frequency domain, and then the signal is subjected to arithmetic processing. Although the signal obtained by this arithmetic processing is converted back into a signal in the time domain and returned, the arithmetic processing (convolution operation) is performed without performing the conversion between the time domain and the frequency domain, that is, while keeping the signal in the time domain. Also, when performing the above, the parts corresponding to the first and second filters are provided with the functions of a low-pass filter, a band-pass filter, and a high-pass filter, so that these filters can be reduced. Therefore, the present invention having such an effect also includes a distortion removing device configured to perform arithmetic processing with a signal in the time domain as it is.

(Twelfth Embodiment) FIG. 13 is a block diagram showing a distortion removing apparatus according to a twelfth embodiment of the present invention.

The distortion removing device 130 includes an A / D converter 11 to which an audio signal output from a sound source 1 such as a CD player is input, a frame dividing device 12, a Fourier transform device 13, and a Fourier transform device 13. And a second filter 132 to which the output signal of the Fourier transformer 13 is input.
A low-pass filter 133 to which an output signal of the second filter 132 is input;
Adder 18 for adding the output signal of the low-pass filter 133 and the output signal of the low-pass filter 133; an inverse Fourier transform device 19 for receiving the output signal of the adder;
And a D / A converter 21.

The first filter 131 is a one-dimensional filter having the function of combining the first storage device 15 and the multiplier 14 in the distortion removing device 10 of FIG. Further, the second filter 132 is a two-dimensional filter having the functions of the second storage device 17 and the multiplication / addition unit 16 in the distortion removal device 10 of FIG.

The distortion removing device 130 is different from that of the first embodiment in that a low-pass filter 133 is provided downstream of the D / A converter 21.

Assuming that the cutoff frequency of the high-frequency side reproduction band of the speaker 22 is mc, the transfer function H1 (m) of the primary system 23 of the speaker 22 is represented by the cutoff frequency mc
It becomes a very small value in a band larger than. Looking at (Equation 9) for calculating the coefficient G2 (m1, m2) of the second filter 132, since H1 (m) is present in the denominator on the right side, the calculated G2 (m1, m2) is compared. It becomes a large value. Therefore, even if the input signal to the distortion removing device 130 satisfies m ≦ mc within the reproduction band of the speaker, the output signal of the second filter 132 is a signal in which the component in the band of mc <m is very large. In this case, this G2 (m
1, m2) to convert the audio signal into a second filter 1
Even if the signal processing is performed at 32, the signal input to the speaker 22 as the distortion compensation signal is a signal having a frequency higher than mc, and thus cannot be actually reproduced.

However, when an audio signal having a very large component in the band of m> mc is input to the speaker 22, the speaker 22 is broken.

Therefore, the distortion removing apparatus 1 of the twelfth embodiment
30 is provided with a low-pass filter 133 at a stage subsequent to the second filter 132, and outputs an output signal of the distortion removing device 130 as mc
By limiting the band below, the speaker 22 is protected from excessive input in the band of mc or more.

On the other hand, the output signal of the
The band can be limited to c or less by devising the characteristics of the second filter 132 instead of providing the low-pass filter 133.

When the reproduction band of the speaker 22 is equal to or less than mc, another problem is as follows. When signal processing is performed on an audio signal using G2 (m1, m2) having a relatively large value in a band where m is equal to or greater than mc,
The output signal of the distortion removing device 130 includes a new distortion due to the signal processing, and is adversely affected such as deterioration of the S / N ratio. Also, when designing the tap G2 (m1, m2) of the second filter 132 by the above method, the characteristic calculated in the frequency domain is converted to the time domain, 0 data is added, and the tap is added to the frequency domain. An operation of re-conversion is performed, but the primary transfer characteristic H1 (m) of the speaker 22 is obtained.
Of the calculated G2 (m1, m2), m ≦ m
Even the components in the band c may be adversely affected, and the distortion compensation effect may be degraded.

Therefore, G2 (m
1, m2) is passed through the area represented by the shaded area in FIG. 14 and is subjected to a two-dimensional band-pass filter that blocks the other areas to obtain a new G2 (m1, m2). When the shaded area in FIG. 14 is expressed by an equation, (Equation 36)
Becomes

[0266]

[Equation 104]

A new G2 (m) obtained by this method
In (1, m2), the region other than the hatched portion in FIG. 14 has very small taps, so that the multiplication and addition operation in the second filter may be performed substantially on the region only in the hatched portion in FIG.

As a result, a distortion compensation signal component having a large amplitude equal to or higher than the cut-off frequency of the high-frequency side reproduction band of the speaker 22 being used is not input to the speaker 22, thereby causing new distortion. And the speaker 22 is not damaged by excessive input outside the reproduction band. Further, according to the new G2 (m1, m2), the filter tap of the component in the band equal to or lower than the cutoff frequency of the speaker 22 is not adversely affected by the tap of the component in the band of m> mc, and the distortion compensation effect is obtained. Is designed.

Next, by utilizing the symmetry and the conjugate property of the tap of the second filter 132, the second
A configuration for reducing the calculation amount in the filter 132 will be described.

The calculation in the second filter 132 may be performed substantially only in the shaded area of FIG. When this area is represented by a mathematical expression, it is expressed by (Equation 37).

[0271]

[Equation 105]

The amount of operation in the second filter 132 is
Since most of the calculation amount in the distortion removing device 130 is occupied, the calculation amount of the distortion removing device 130 is greatly reduced by limiting the calculation to the area shown by the hatched portion in FIG.

Also, G2 (m1, m2
When calculating 2), the transfer function H2 (m1, m2) of the distortion of the speaker 22 represented as a two-dimensional array of N3 × N3.
m2) needs to be measured.
At 0, the measurement may be performed only in the region indicated by the hatched portion in FIG. When this is expressed by a mathematical formula, (Equation 38)
Becomes

[0274]

[Equation 106]

In the twelfth embodiment, the low-pass filter 133 can be inserted after the adder 18.

(Thirteenth Embodiment) FIG. 17 is a block diagram showing a distortion removing apparatus according to a thirteenth embodiment of the present invention.

The distortion removing device 170 includes an A / D converting device 11 to which an audio signal output from the sound source 1 such as a CD player is input, a frame dividing device 12, a Fourier transforming device 13, and a Fourier transforming device 13. And a second filter 172 to which the output signal of the Fourier transform device 13 is input.
A bandpass filter 173 to which an output signal of the second filter 172 is input;
1, an adder 18 for adding the output signal of the band-pass filter 173, an inverse Fourier transform device 19 for inputting the output signal of the adder, a frame synthesizing device 20, a D / A converting device 21 And

The first filter 171 is a one-dimensional filter having the function of combining the first storage device 15 and the multiplier 14 in the distortion removing device 10 of FIG. Further, the second filter 172 is a two-dimensional filter having the functions of the second storage device 17 and the multiplying / adding device 16 in the distortion removing device 10 of FIG.

The distortion removing device 170 differs from that of the first embodiment in that a band-pass filter 173 is provided downstream of the second filter 172.

It is assumed that the lower cut-off frequency of the reproduction band of speaker 22 is mcl, and the cut-off frequency of the higher reproduction band is mch. Frequency m is m <m
In the band of cl and mch <m, the transfer function H1 (m) of the primary system 23 of the speaker 22 has a very small value. Therefore, according to (Equation 9) for calculating the coefficient of the second filter 172, since the denominator on the right side has H1 (m), the calculated G2 (m1, m2) is a relatively large value. Become. Therefore, even if the input signal to the distortion removing device 170 satisfies mcl ≦ m ≦ mch in the reproduction band of the speaker 22, the output signal of the second filter 172 is
2 is a signal in which the component outside the reproduction band is very large. In this case, even if the audio signal is processed by the second filter 172 using G2 (m1, m2), the signal input to the speaker 22 as the distortion compensation signal is a signal outside the reproduction band, and therefore, in reality, I can't play it.

However, when a very large audio signal outside the reproduction band is input to the speaker 22, there is a problem that the speaker 22 is broken.

Therefore, the distortion removing apparatus 1 of the thirteenth embodiment
70 protects the speaker 22 from an excessive input outside the reproduction band by providing a band-pass filter 173 at the subsequent stage of the second filter 172 and limiting the output signal of the distortion removing device 170 to within the reproduction band of the speaker 22. ing.

On the other hand, in order to limit the output signal of the distortion removing device 170 to within the reproduction band of the speaker, the D / A converter 2
Instead of providing the band-pass filter 173 at the subsequent stage of one, it can also be realized by devising the characteristics of the second filter 172.

[0284] The reproduction band of the speaker 22 is not less than mcl and mc.
When it is less than h, there is another problem as follows. G2 of a relatively large value outside the reproduction band of the speaker 22
If the signal processing is performed on the audio signal according to (m1, m2), the output signal of the distortion removing device 170 will have an adverse effect such as including a new distortion due to the signal processing and a deterioration in the S / N ratio. Further, when designing the tap G2 (m1, m2) of the second filter 172 by the above method, the characteristic calculated in the frequency domain is converted into the time domain, 0 data is added, and the tap is added to the frequency domain tap. An operation of re-conversion is performed.
3 out of the reproduction band of the speaker 22 in the transfer characteristic H1 (m) of FIG.
Of 2 (m1, m2), even components within the reproduction band of the speaker 22 may be adversely affected, and the distortion compensation effect may be degraded.

Therefore, G2 (m
1, m2) is passed through a shaded area in FIG. 18 and is subjected to a two-dimensional band-pass filter that blocks the other areas to obtain a new G2 (m1, m2). When the shaded area in FIG. 18 is represented by an equation, (Equation 39)
Becomes

[0286]

[Equation 107]

A new G2 (m) obtained by this method
According to (1, m2), since the area other than the hatched area in FIG. 18 has very small taps, the multiplication and addition operation in the second filter may be performed substantially on the area only in the hatched area in FIG. .

As a result, a large-amplitude distortion compensation signal component outside the reproduction band of the speaker 22 being used is not input to the speaker 22, thereby causing new distortion or causing a distortion outside the reproduction band. The excessive input does not damage the speaker 22. Further, according to the new G2 (m1, m2), the filter tap related to the component in the reproduction band of the speaker 22 is not adversely affected by the tap related to the component outside the reproduction band, and the distortion compensation effect is large. A filter tap is designed.

Next, by utilizing the symmetry and the conjugate property of the tap of the second filter 172, the second
A configuration for reducing the amount of calculation in the filter 172 will be described.

The calculation in the second filter 172 may be performed substantially only in the shaded region of FIG. When this area is represented by a mathematical expression, it is (Equation 40).

[0291]

[Equation 108]

Since the amount of calculation in the second filter occupies most of the amount of calculation in the distortion removing device 170, the amount of calculation in the distortion removing device is limited by limiting the calculation to the area shown by the hatched portion in FIG. Is greatly reduced.

Further, G2 (m1, m
When calculating 2), the transfer function H2 (m1, m2) of the distortion of the speaker 22 represented as a two-dimensional array of N3 × N3.
m2) needs to be measured.
At 0, the measurement may be performed only in the area indicated by the hatched portion in FIG. When this is expressed by a mathematical formula, (Equation 41)
Becomes

[0294]

(Equation 109)

In the thirteenth embodiment, the band pass filter 173 can be inserted after the adder 18.

(Fourteenth Embodiment) FIG. 21 is a block diagram showing a distortion removing apparatus according to a fourteenth embodiment of the present invention.

The distortion removing device 210 includes an A / D converter 11 to which an audio signal output from a sound source 1 such as a CD player is input, a frame dividing device 12, a Fourier transforming device 13, and a Fourier transforming device 13. And a second filter 212 to which the output signal of the Fourier transform device 13 is input.
A high-pass filter 213 to which an output signal of the second filter 212 is input;
Adder 18 for adding the output signal of the high-pass filter 213 to the output signal of the high-pass filter 213; an inverse Fourier transform device 19 for receiving the output signal of the adder;
And a D / A converter 21.

The first filter 211 is a one-dimensional filter having the function of combining the first storage device 15 and the multiplier 14 in the distortion removing device 10 of FIG. The second filter 212 is a two-dimensional filter having the functions of the second storage device 17 and the multiplier / adder 16 in the distortion removing device 10 of FIG.

The distortion removing device 210 differs from that of the first embodiment in that a high-pass filter 213 is provided at a stage subsequent to the second filter 212.

The speaker 22 is a high-frequency horn speaker, and can reproduce an audio signal having a low-frequency cut-off frequency mc or higher. In this case, in a band lower than the cutoff frequency mc of the speaker 22, the transfer function H1 (m) of the primary system 23 of the speaker 22 has a very small value. Therefore, according to (Equation 9) for calculating the coefficient of the second filter 212, the denominator on the right side is H1
G2 (m1, m2) calculated due to (m)
Is a relatively large value in the region of m <mc. Therefore, the input signal to the distortion removing device 210 is
Even if mc ≦ m in the reproduction band of the second filter 21
The output signal of No. 2 has a very large component outside the reproduction band of the speaker 22. In this case, G2 (m1, m2)
Even if the audio signal is signal-processed by the second filter 212, the signal input to the speaker 22 as the distortion compensation signal is out of the reproduction band, and cannot be actually reproduced.

However, when a very large audio signal outside the reproduction band is input to the speaker 22, there is a problem that the speaker 22 is broken.

Therefore, the distortion removing device 2 of the fourteenth embodiment
10, a high-pass filter 213 is provided after the second filter 212 to limit the output signal of the distortion removing device 210 to within the reproduction band of the speaker 22, thereby protecting the speaker 22 from an excessive input outside the reproduction band. I have.

To limit the output signal of the distortion removing device 210 to within the reproduction band of the speaker 22, a high-pass filter 2
Instead of providing 13, it can also be realized by devising the characteristics of the second filter 212.

When the reproduction band of the speaker 22 is equal to or more than mc, there is another problem as follows. G2 (m1, m2) of a relatively large value outside the reproduction band of the speaker 22
When the signal processing is performed on the audio signal, the output signal of the distortion removal device 210 includes a new distortion due to the signal processing, or has an adverse effect such as a deterioration in the S / N ratio. In designing the tap G2 (m1, m2) of the second filter 212 by the above method,
An operation of converting the characteristic calculated in the frequency domain to the time domain, adding 0 data, and converting the characteristic again into a tap in the frequency domain is performed, but the transfer characteristic H1 (m) of the primary system 23 of the speaker 22 is changed. Of these, the component outside the reproduction band of the speaker 22 is too small, so that the calculated G2 (m1, m2
In 2), even components within the reproduction band of the speaker 22 may be adversely affected, and the distortion compensation effect may be degraded.

Therefore, G2 (m
1, m2) is multiplied by a two-dimensional band-pass filter that passes an area indicated by the hatched portion in FIG. 22 and blocks the other areas to obtain a new G2 (m1, m2).
Expressing the shaded area in FIG. 22 by an equation gives (Equation 42).

[0306]

[Equation 110]

The new G2 (m
According to (1, m2), since the area other than the shaded area in FIG. 22 has very small taps, the multiplication and addition operation in the second filter may be performed substantially on the area only in the shaded area in FIG. .

As a result, a large-amplitude distortion compensation signal component outside the reproduction band of the speaker 22 being used is not inputted to the speaker 22, thereby causing new distortion or causing a distortion outside the reproduction band. The excessive input does not damage the speaker 22. Further, according to the new G2 (m1, m2), the filter tap related to the component in the reproduction band of the speaker 22 is not adversely affected by the tap related to the component outside the reproduction band, and the distortion compensating effect is not affected. Large filter taps are designed.

Next, by utilizing the symmetry and the conjugate property of the tap of the second filter 212, the second
A configuration for reducing the amount of multiplication and addition performed by the filter 212 will be described.

The calculation in the second filter 212 may be substantially performed by multiplying and adding only in the shaded area of FIG. When this area is represented by a mathematical expression, it is represented by (Equation 43).

[0311]

(Equation 111)

The amount of calculation in the second filter 212 is
Since most of the calculation amount in the distortion removal device 210 is occupied, the calculation amount of the distortion removal device 210 is greatly reduced by limiting the calculation to the area shown by the hatched portion in FIG.

Also, G2 (m1, m2
When calculating 2), the transfer function H2 (m1, m2) of the distortion of the speaker 22 represented as a two-dimensional array of N3 × N3.
m2) needs to be measured.
At 0, the measurement may be performed only in the region indicated by the hatched portion in FIG. When this is expressed by a mathematical formula, (Equation 44)
Becomes

[0314]

[Equation 112]

In the fourteenth embodiment, the high-pass filter 213 can be inserted after the adder 18.

Further, the distortion removing devices 130, 170, 210 of the twelfth to fourteenth embodiments may be applied in place of the distortion removing devices 10, 40 in the processing speaker system 50 of the fourth embodiment, or the fifth embodiment. May be applied instead of the distortion removing devices 10 and 40 in the multiprocessor 60.

(Fifteenth Embodiment) FIG. 25 is a block diagram showing a distortion removing apparatus according to a fifteenth embodiment of the present invention. In the fifteenth embodiment, as apparent from FIG. 25, it is assumed that a distortion removing device 250 is provided in an audio reproduction system in which a processor 253 such as a graphic equalizer is connected in front of the speaker 22.

[0318] The distortion removing device 250 of the fifteenth embodiment comprises:
Processor 2 such as a graphic equalizer in the subsequent stage
Even when there is 53, distortion generated in the speaker 22 can be removed. The configuration of the distortion removing device 250 is the same as that of each of the other embodiments described above.
90, etc., but the second filter 252
Are different in the method of calculating the coefficient G2 (m1, m2).

[0319] In the distortion removing devices 10, 70, 90, etc. of the other embodiments described above, after the first filter and the second filter are designed to remove the distortion generated in the speaker 22, However, if a processor 253 such as a graphic equalizer is connected to the subsequent stage of the distortion removing device, there is a problem that the distortion removing effect of the speaker 22 is deteriorated, and in some cases, the effect is almost lost. In order to solve this problem, it is necessary to newly measure the first-order transfer characteristics and the second-order distortion transfer characteristics of the entire downstream side of the distortion removing device and calculate the coefficient of the second filter.

However, when the processor 253 is replaced with another model, or when the characteristics of the processor 253 are changed in the process of sound quality adjustment, the transfer characteristics H1 (m) of the primary system 23 of the speaker 22 and Secondary system 24
It was very troublesome to newly measure the distortion transfer characteristic H2 (m1, m2).

Therefore, in the fifteenth embodiment, the characteristic of the second filter 252 is corrected using the characteristic of the inserted processor 253, so that the distortion of the speaker 22 can be removed without performing new measurement. Removal device 250
Is provided.

Next, the distortion removing device 25 of the fifteenth embodiment will be described.
A method of determining the transfer characteristics of the first filter 251 and the second filter 252 at 0 will be described.

First, by expression in the frequency domain,
Input signal X (m) and output signal W of distortion removing device 250
The relationship of (m) is expressed by (Equation 45) similarly to the distortion removing apparatuses 10, 70, 90, etc. of the other embodiments described above.

[0324]

[Equation 113]

Next, the input signal W to the processor 253
The relationship between (m) and the output signal Y (m) of the speaker 22 is shown in (Equation 46).

[0326]

[Equation 114]

E (m) is a transfer function of the processor 253,
H1 (m) is the transfer function of the primary system 23 of the speaker 22,
H2 (m1, m2) is a transfer function of the second-order system 24 which is a transfer function of the harmonic distortion component and the intermodulation distortion component of the speaker 22, and the addition of the first and second terms on the right side is a function of the adder 25. Represents

By substituting (Equation 45) into (Equation 46), X
When the relationship between (m) and Y (m) is obtained, it becomes (Equation 47).

[0329]

[Equation 115]

In the first term on the right side of (Equation 47), X (m) is the first filter 251, the processor 253, and the speaker 22.
The first term in the curly braces of the second term on the right side of the component that has passed through the first-order system 23 is that the X (m) has passed through the first-order system 23 of the second filter 252, the processor 253, and the speaker 22. component,
The second term in the curly braces of the second term on the right side is a component in which X (m) has passed through the first filter 251, the processor 253, and the secondary system 24 of the speaker 22. Note that X (m) is the second filter 252, the processor 253, and the speaker 22.
Components that have passed through the next system 24 are omitted because they are too small compared to the other terms.

In order for the output signal Y (m) of the speaker 22 to have the desired characteristics, first, as in the distortion removing devices 10, 70, 90, etc. of the other embodiments, (Equation 4)
G1 so that the first term on the right side of 7) becomes equal to the desired characteristic.
(M) is determined. For example, the processor 25 is stored in X (m).
In the case where it is desired to make Y (m) equal to the characteristic obtained by multiplying the characteristic of No.3, that is, when it is desired to set Y (m) = E (m) X (m), G1 (m) is set to the primary system of the speaker 22. Inverse characteristics (G
1 (m) = 1 / H1 (m)).

Next, in order to compensate for the secondary distortion generated in the secondary system of the speaker 22, the first and second terms in the braces on the right side of (Equation 47) may be canceled. . Therefore, G
2 (m1, m2) is determined as in (Equation 48).

[0333]

[Equation 116]

The new G2 (m1, m2) is obtained by adding the transfer characteristics E (m1) and E (m2) of the processor 253 to G2 (m1, m2) before the processor 253 is inserted.
Is multiplied by Therefore, when the processor 253 is inserted into the sound reproduction system, the processor 253
, The coefficient G2 (m1, m2) of the second filter 252 of the distortion removing device 250 can be corrected. Therefore, it is possible to remove the distortion of the speaker 22 without having to newly measure the transfer characteristic on the subsequent stage of the distortion removing device 250.

(Sixteenth Embodiment) FIG. 26 is a block diagram showing a distortion removing apparatus according to a sixteenth embodiment of the present invention.

The difference between the distortion removing device 260 and the distortion removing device 250 of the fifteenth embodiment is that the processor 25
3 in that it includes a detection device 264 for the transfer characteristic E (m) and an updating device 263 for updating the characteristic G2 (m1, m2) of the coefficient of the second filter 262.

When the transfer characteristic E (m) of the processor 253 is changed, the detecting device 264 detects E (m) and sends it to the updating device 263. The updating device 263 receives the characteristic E of the processor 253 sent from the detecting device 264.
By substituting (m) into (Equation 48) described in the fifteenth embodiment, the coefficient G2 (m1, m2) of the second filter 262 is calculated, and the coefficient of the second filter 262 is updated.

Thus, even if the characteristics of the processor 253 provided at the subsequent stage of the distortion removing device 260 are changed, the distortion of the speaker 22 can be removed.

In order to actually make the transfer characteristic G1 (m) of the first filter 261 the inverse characteristic of the primary system 23 of the speaker 22, the inverse characteristic (1 / H1 (m)) is used. It must be multiplied, but is omitted in the above expression for simplicity.

The transfer characteristic E of the processor 253
(M) may be considered as a transfer characteristic of a graphic equalizer or a power amplifier.

(Seventeenth Embodiment) FIG. 27 is a block diagram showing a speaker multiprocessor according to a seventeenth embodiment of the present invention.

In the seventeenth embodiment, the distortion removing device 250 of FIG. 25 or the distortion removing device 260 of FIG. 26 is incorporated in the speaker multiprocessor 270.

In general, when an audio signal is reproduced by a professional speaker, a sound source 1 and a speaker 22
A signal processor called a multiprocessor is inserted to adjust sound quality. However, if the transfer characteristic of the multiprocessor is changed after the coefficient of the second filter of the distortion removing device is determined, the distortion removing effect of the speaker 22 is deteriorated or almost eliminated. Therefore, when the transfer characteristics of the multiprocessor are changed,
The coefficients of the second filter 262 need to be updated.

Therefore, the distortion removing device 250 of FIG. 25 or the distortion removing device 260 of FIG.
Built-in. Thereby, the distortion of the speaker 22 can be removed without increasing the number of devices constituting the sound reproduction system.

(Eighteenth Embodiment) FIG. 28 is a block diagram showing a speaker power amplifier according to an eighteenth embodiment of the present invention.

In the eighteenth embodiment, the distortion removing device 250 shown in FIG. 25 or the distortion removing device 260 shown in FIG. 26 is built in the speaker power amplifier 280.

Generally, when an audio signal is reproduced by the speaker 22, a power amplifier is connected in front of the speaker 22 to adjust the volume. However, if the gain of the power amplifier is changed after the coefficient of the second filter of the distortion removal device is determined, the distortion removal effect of the speaker 22 is deteriorated or almost eliminated. Therefore, when the gain of the power amplifier is changed, it is necessary to update the coefficient of the second filter 262.

Therefore, the power amplifier 280 incorporates the distortion removing device 250 of FIG. 25 or the distortion removing device 260 of FIG. Thereby, the distortion of the speaker 22 can be removed without increasing the number of devices constituting the sound reproduction system.

(Nineteenth Embodiment) FIG. 29 is a block diagram showing a processing speaker system according to a nineteenth embodiment of the present invention.

In the nineteenth embodiment, the multiprocessor 270 shown in FIG. 27 or the power amplifier 280 shown in FIG. 28 is incorporated in the processing speaker system 290.

In particular, since the professional speaker 22 reproduces an audio signal at a high volume, non-linear distortion is likely to occur. The processing speaker system 290 shown in FIG.
Multiprocessor 270 or power amplifier 2 of FIG.
If the signal processing of the distortion compensation is performed by incorporating the built-in 80, the sound quality can be improved.

(Twentieth Embodiment) FIG. 30 is a block diagram showing a distortion removing apparatus according to a twentieth embodiment of the present invention. The distortion removing apparatus 300 of the twentieth embodiment is capable of simultaneously removing the distortion generated in the power amplifier 303 and the distortion generated in the speaker 22 when the power amplifier 303 in the subsequent stage generates secondary distortion. . The configuration of the distortion removing device 300 is almost the same as the distortion removing devices 10, 70, 90, etc. of the respective embodiments described above, except that the coefficient G2 (m1,
The calculation method of m2) is different.

[0353] The distortion removing device 1 of each of the embodiments described above.
For 0, 70, 90, etc., the amplifier 303 and the speaker 2
The first filter and the second filter were designed to remove the distortion generated on the entire rear side of the distortion removing device including the second filter.

However, after designing these filters, if the gain of the power amplifier 303 that causes distortion is changed, or if the model is changed to a model having a different transfer characteristic of second-order distortion, the distortion of the speaker 22 will be reduced. There has been a problem that the removal effect is deteriorated, and in some cases, the effect is almost lost. To solve this problem,
The first-order transfer characteristic and the second-order distortion transfer characteristic of the entire rear stage of the distortion removing device must be newly measured to calculate the coefficient of the second filter.

However, when the gain of the amplifier 303 is adjusted or replaced with another model, the transfer characteristics of the primary and secondary distortions of the entire rear side of the distortion removing device are newly measured. Was very troublesome.

Therefore, the distortion removing device 3 according to the twentieth embodiment is described.
00 is 1 of the power amplifier 303 in the previous stage of the speaker 22.
A new measurement is performed by correcting the characteristic of the second filter 302 using the transfer characteristic A1 (m) of the next system 304 and the transfer characteristic A2 (m1, m2) of the second-order distortion system 305. Thus, the distortion of the speaker 22 can be removed.

Next, the distortion removing device 30 of the twentieth embodiment will be described.
A method for determining the transfer characteristics of the first filter 301 and the second filter 302 at 0 will be described.

First, by expression in the frequency domain,
Input signal X (m) and output signal W of distortion removing apparatus 300
The relationship of (m) is represented by (Equation 45), similarly to the distortion removal devices 10, 70, 90, etc. of the above embodiments.

The relationship between the input signal W (m) and the output signal U (m) of the power amplifier 300 that causes the secondary distortion is as shown in (Equation 49).

[0360]

[Formula 117]

A1 (m) is the primary system 30 of the amplifier 303.
A2 (m1, m2) is the transfer function of the amplifier 303
The transfer function of the second-order distortion system 305, the addition of the first and second terms on the right side, represents the function of the adder 18.

Next, the input signal U (m) to the speaker 22
And the output signal Y (m) of the speaker 22 is given by (Equation 50).

[0363]

[Equation 118]

Here, (Equation 45), (Equation 49), and (Equation 5)
0), W (m) and U (m) are deleted, and the relationship between X (m) and Y (m) is obtained.

[0365]

[Equation 119]

The first term on the right side of (Equation 51) is the component of X (m) passing through the first filter 301, the primary system 304 of the amplifier 303, and the primary system 23 of the speaker 22, and the second term on the right side. The first term in square brackets of the term is that X (m) is the second filter 30
2 and the primary system 304 of the power amplifier 303 and the speaker 2
The first component in the second brace in the square bracket of the second term on the right-hand side of the component passing through the first-order system 23 of X2 is X (m) in the first filter 301 and the power amplifier 303 in the second term. The component that has passed through the next system 305 and the first-order system 23 of the speaker 22, the second term in the curly braces in the second bracket in the second term on the right side, and X (m) is the first filter 301 And the primary system 3 of the power amplifier 303
This is a component that has passed through the secondary system 24 of the speaker 04 and the speaker 22. Note that the component of X (m) passing through at least two or more of the second system 302 of the second filter 302, the power amplifier 303, and the secondary system 24 of the speaker 22 is smaller than the other terms. Therefore, it is omitted.

In order for the output signal Y (m) of the speaker 22 to have desired characteristics, first, G1 (m) is set so that the first term on the right side of (Equation 51) becomes equal to the desired characteristics. decide. For example, Y (m) is a characteristic in which X (m) is amplified by power amplifier 303, that is, Y (m) = A
(M) If we want to be X (m), G1
(M) is the inverse characteristic of the primary system 23 of the speaker 22 (G1
(M) = 1 / H1 (m)).

To actually make G1 (m) the inverse characteristic of the primary system 23 of the speaker 22, the inverse characteristic (1 / H1
It is necessary to multiply (m)) by the delay characteristic,
The above expression is omitted for simplicity.

Next, the speaker 22 and the power amplifier 30
Consider the characteristic G2 (m1, m2) of the second filter 302 that can compensate for the distortion generated in the third filter 302. In order to prevent the distortion signal from being included in the output signal Y (m) of the speaker 22, the first term and the second term in the brackets of the second term in (Equation 51) need only be canceled. Thus, G2 (m1, m2) is determined as in (Equation 52).

[0370]

[Equation 120]

This new G2 (m1, m2) is obtained by replacing G2 (m1, m2) before the amplifier 303 is inserted with the amplifier 3
03 transfer characteristics A1 (m1) and A of the primary system 304
1 (m2) and the transfer characteristic A2 (m1, m2) of the system 305 of the secondary distortion of the amplifier. Therefore, when the power amplifier 303 is changed to another model in the sound reproduction system, the amplifier 303
Using the transfer characteristic A1 (m) of the first-order system 304 and the transfer characteristic A2 (m1, m2) of the second-order distortion system 305, the coefficient G2 of the second filter 302 of the distortion removal apparatus 300.
(M1, m2) can be corrected. therefore,
The distortion of the loudspeaker 22 and the distortion of the power amplifier 303 can be eliminated without the need to newly measure the transfer characteristic on the subsequent stage of the distortion elimination device 300.

(Twenty-First Embodiment) FIG. 31 is a block diagram showing a twenty-first embodiment which is a distortion removing apparatus according to the present invention. In the distortion removing apparatus 310 of the twenty-first embodiment, even if the gain of the power amplifier 303 is changed,
And the distortion of the amplifier 303 can be removed.

The distortion removing device 310 is different from the distortion removing device 300 of the twentieth embodiment in that the transfer characteristic A1 (m) of the primary system 304 of the amplifier 303 and the amplifier 30
The storage device 314 detects the model of the amplifier 0 and the transfer characteristic of the second-order distortion system 305 of the amplifier 303 according to the model A1 (m) of the primary system 304 of the amplifier 303 and the amplifier. A device 315 and an updating device 313 for updating the characteristic G2 (m1, m2) of the coefficient of the second filter 312
It is equipped with.

When the transfer characteristic A1 (m) of the primary system 304 of the amplifier 303 is changed, the detection device 314
(M) is detected and sent to the updating device 313. The update device 313 stores, from the storage device 315, the transfer characteristic A2 (m1, m2) of the second-order distortion system 305 of the new amplifier corresponding to the characteristic A1 (m) of the new amplifier 303 sent from the detection device 314. read out. Then, the update device 313
Is the new A1 (m) and the new A2 (m1, m2)
Is substituted into (Equation 52) described in the twentieth embodiment, the coefficient G2 (m1, m2) of the second filter 312 is calculated, and the coefficient of the second filter 312 is updated.

Thus, even when the characteristics of the amplifier 303 provided at the subsequent stage of the distortion removing device 310 are changed, the distortion generated in the speaker 22 and the distortion generated in the amplifier 303 can be removed.

In order to actually make G1 (m) the inverse characteristic of the primary system 23 of the speaker 22, the inverse characteristic (1 / H1
It is necessary to multiply (m)) by the delay characteristic,
The above expression is omitted for simplicity.

(Twenty-second Embodiment) FIG. 32 is a block diagram showing a speaker power amplifier according to a twenty-second embodiment of the present invention.

In the twenty-second embodiment, the distortion removing device 300 shown in FIG. 30 or the distortion removing device 310 shown in FIG. 31 is incorporated in the speaker power amplifier 320.

In general, when an audio signal is reproduced by the speaker 22, a power amplifier is connected in front of the speaker 22 to adjust the volume. However, if the gain of the power amplifier is changed after the coefficient of the second filter of the distortion removal device is determined, the distortion removal effect of the speaker 22 is deteriorated or almost eliminated. Therefore, when the gain of the power amplifier is changed, it is necessary to update the coefficient of the second filter 262.

Therefore, the power amplifier 320 incorporates the distortion removing device 300 of FIG. 30 or the distortion removing device 310 of FIG. As a result, it is possible to remove the distortion generated in the secondary distortion system 305 of the power amplifier and the speaker 22 without increasing the number of devices constituting the sound reproduction system.

(Twenty-third Embodiment) FIG. 33 is a block diagram showing a speaker multiprocessor according to a twenty-third embodiment of the present invention.

In the twenty-third embodiment, the distortion removing device 300 of FIG. 30 or the distortion removing device 310 of FIG. 31 is incorporated in the speaker multiprocessor 330.

Generally, when an audio signal is reproduced by a commercial speaker, a signal processing device called a multiprocessor is inserted between a sound source and a power amplifier for driving the speaker to adjust sound quality. However, if the transfer characteristic of the multiprocessor is changed after the coefficient of the second filter 312 of the distortion removal device is determined, the distortion removal effect of the speaker 22 is deteriorated or almost lost. Therefore, when the transfer characteristic of the multiprocessor is changed, it is necessary to update the coefficient of the second filter 312.

Therefore, the distortion removing device 300 of FIG. 30 or the distortion removing device 310 of FIG.
Built-in. As a result, the second-order distortion system 3 of the multiprocessor can be used without increasing the number of devices constituting the sound reproduction system.
05 and the speaker 22 can be eliminated.

(24th Embodiment) FIG. 34 shows a processing speaker system 3 according to a 24th embodiment of the present invention.
40 is shown. The processing speaker system 340 incorporates the distortion removing device 300 of FIG. 30 or the distortion removing device 310 of FIG. 31, and applies the output of the distortion removing device to the speaker 22.

Particularly, in the field of business use, since a large volume is generated by the speaker 22, non-linear distortion is likely to occur, and the distortion removing device 300 of FIG.
The sound quality can be improved by incorporating the distortion removal device 310 of (1) and performing signal processing for distortion compensation.

[0387]

As described above, according to the present invention, even if the cause of the distortion is not clear, a test signal is input to the nonlinear system to measure the transfer function of the distortion. By designing a Volterra filter and performing convolution of the Volterra filter in the frequency domain, nonlinear distortion is removed.

Even when the first-order transfer characteristic of the nonlinear system includes a delay, the distortion of the nonlinear system is removed by reflecting the delay characteristic on a two-dimensional filter that generates a nonlinear distortion compensation signal.

[0389] Further, in the distortion removing apparatus, the input audio signal is processed in the frequency domain, thereby enabling real-time processing.

When the audio signal is divided into frames and captured by the distortion removal apparatus capable of real-time processing, the frame length and the overlap width are determined so that the amount of convolution operation after the capture is minimized.

Further, in a two-dimensional filter for generating a distortion compensation signal for removing non-linear second-order distortion, the amount of operation is reduced by reducing the substantial convolution operation area.

Also, by including a low-pass filter characteristic, a band-pass filter characteristic, or a high-pass filter characteristic in the one-dimensional and two-dimensional filter characteristics of the distortion removing device, the frequency band of the audio signal to be reproduced is limited. Only let through. As a result, the distortion removing device can have those functions without adding a device such as a low-pass filter, a band-pass filter, or a high-pass filter to the sound reproducing system.

Further, in a distortion removing device having a function of a low-pass filter, a band-pass filter, or a high-pass filter, the amount of computation is reduced by reducing the area of the convolution operation in the two-dimensional filter in the distortion removing device. .

Further, when the reproduction band of the speaker generating the distortion is limited to a certain frequency band, it is not necessary to output the distortion compensation signal for canceling the distortion generated outside the reproduction band of the speaker from the distortion removing device. . This prevents the distortion compensation signal from being forcibly input to the speaker when the distortion compensation signal is out of the reproduction band of the speaker.

Further, in a distortion removing apparatus designed so as not to output a distortion compensation signal outside the reproduction band of the speaker, the amount of computation is reduced by reducing the area of the convolution operation in the two-dimensional filter in the distortion removing apparatus. Let it be reduced.

[0396] Even when a processor such as a graphic equalizer is inserted at the subsequent stage of the distortion removing device, it is possible to remove the distortion generated by the speaker. In general, if a graphic equalizer or the like is newly inserted after the distortion removing device after determining the coefficients of the one-dimensional and two-dimensional filters in the distortion removing device, the distortion removing effect is deteriorated. By correcting the coefficients in the processor, the same distortion removing effect as before can be obtained.

Further, in a sound reproduction system having a processor such as a graphic equalizer at the subsequent stage of the distortion removing device, when the characteristics of the graphic equalizer are changed, the filter coefficients in the distortion removing device are automatically updated, and are always updated. The distortion generated in the speaker is removed.

In addition, it is possible to remove the distortion generated in the speaker and the distortion generated in the power amplifier for the speaker installed at the subsequent stage of the distortion removing device.

Further, in a distortion removing device which can remove distortion generated in a speaker power amplifier installed on the subsequent stage of the distortion removing device, when the gain of the power amplifier is changed, the distortion removing device Are automatically updated, and the nonlinear distortion of the speaker can always be removed.

When the convolution operation area of the two-dimensional filter in the distortion removing device is reduced in order to reduce the operation amount, the transfer function of the speaker distortion necessary for determining the coefficient of the two-dimensional filter is reduced. Reduce the number of measurement points,
Provided is a measurement method capable of shortening the measurement time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a distortion removing apparatus according to a first embodiment of the present invention.

FIG. 2A is a frame diagram in a time domain showing a method of dividing a frame in a frame dividing device of the distortion removing device of the first embodiment.

FIG. 2B is a time-domain frame diagram showing a method of connecting audio signals in the frame synthesizing apparatus.

FIG. 2C is a diagram showing a part of an operation performed in a time domain in a process of calculating a coefficient to be stored in the first storage device.

FIG. 2D is a diagram showing a part of an operation performed in a time domain in a process of calculating a two-dimensional coefficient stored in a second storage device.

FIG. 3A is a diagram illustrating a region of a two-dimensional filter to be substantially calculated in a multiply-adder that performs a calculation of a two-dimensional filter in a distortion removal device according to a second embodiment.

FIG. 3B is a diagram showing that taps of a two-dimensional filter have line-symmetric characteristics with a diagonal axis as a symmetry axis.

FIG. 3C is a diagram showing that taps of the two-dimensional filter have a conjugate relationship with the center point of the tap being a point-symmetric center point.

FIG. 3D is a diagram showing that the result of the convolution operation in the two-dimensional filter in the distortion removal device according to the second embodiment has a conjugate relationship between the hatched portion and the other region.

FIG. 4 is a block diagram showing a distortion removing device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a processing speaker system according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram illustrating a multiprocessor according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram showing a distortion removing device according to a sixth embodiment of the present invention.

FIG. 8A is a diagram illustrating a first example of a region of a two-dimensional filter to be substantially calculated in a second filter of the distortion removal device of the seventh embodiment having a low-pass filter characteristic.

FIG. 8B is a diagram illustrating a second example of a two-dimensional filter area to be substantially calculated in the second filter of the distortion removing apparatus according to the seventh embodiment having a low-pass filter characteristic.

FIG. 9 is a block diagram showing a distortion removing apparatus according to an eighth embodiment of the present invention.

FIG. 10A is a diagram illustrating a first example of a region of a two-dimensional filter to be substantially calculated in a second filter of the distortion removal device according to the ninth embodiment having bandpass filter characteristics.

FIG. 10B is a diagram illustrating a second example of a two-dimensional filter region to be substantially calculated in the second filter of the distortion removing apparatus according to the ninth embodiment that also has bandpass filter characteristics.

FIG. 11 is a block diagram showing a distortion removing apparatus according to a tenth embodiment of the present invention.

FIG. 12 is a diagram showing a region of a two-dimensional filter to be substantially calculated in a second filter of the distortion removing device of the eleventh embodiment having a high-pass filter characteristic.

FIG. 13 is a block diagram showing a distortion removing apparatus according to a twelfth embodiment of the present invention.

FIG. 14 shows a region in which a convolution operation is to be substantially performed in a two-dimensional filter provided in a distortion removing apparatus according to a twelfth embodiment in order to limit an output signal to a reproduction band cutoff frequency of a nonlinear system or lower. FIG.

FIG. 15 illustrates a two-dimensional filter provided in the distortion removal apparatus in order to reduce the amount of calculation in the distortion removal apparatus according to the twelfth embodiment that restricts the output signal to be equal to or lower than the reproduction band cutoff frequency of the nonlinear system. FIG. 4 is a diagram showing a region where a convolution operation is to be performed substantially.

FIG. 16 is a diagram illustrating a transfer function of a second-order distortion of a nonlinear system when determining a tap of a two-dimensional filter in the distortion removing apparatus according to the twelfth embodiment that limits an output signal to a frequency equal to or lower than a reproduction band cutoff frequency of the nonlinear system. FIG. 3 is a diagram showing a region to be measured among the above.

FIG. 17 is a block diagram illustrating a distortion removing apparatus according to a thirteenth embodiment of the present invention.

FIG. 18 shows a region where a convolution operation is to be substantially performed in a two-dimensional filter provided in the distortion removing apparatus of the thirteenth embodiment in order to limit the output signal to within the reproduction band of the nonlinear system. FIG.

FIG. 19 is a block diagram of a distortion removing apparatus according to a thirteenth embodiment for limiting an output signal to within a reproduction band of a nonlinear system.
FIG. 4 is a diagram illustrating a region where a convolution operation is to be substantially performed in a dimensional filter.

FIG. 20 illustrates a second embodiment of the distortion removing apparatus according to the thirteenth embodiment for limiting the output signal to within the reproduction band of the nonlinear system.
FIG. 7 is a diagram illustrating a region to be measured in a transfer function of a second-order distortion of a nonlinear system when a tap of a dimensional filter is determined.

FIG. 21 is a block diagram showing a distortion removing device according to a fourteenth embodiment of the present invention.

FIG. 22 is a diagram showing a region where a convolution operation is to be substantially performed in a two-dimensional filter provided in a distortion removing apparatus according to a fourteenth embodiment in order to limit an output signal to within a reproduction band of a nonlinear system. It is.

FIG. 23 is a diagram illustrating a configuration of a distortion removal apparatus according to a fourteenth embodiment for limiting the output signal to within the reproduction band of the nonlinear system, in order to reduce the amount of computation.
FIG. 6 is a diagram illustrating a region where a convolution operation is to be substantially performed in a dimensional filter.

FIG. 24 shows a second embodiment of the distortion removing apparatus according to the fourteenth embodiment for limiting the output signal to within the reproduction band of the nonlinear system.
FIG. 7 is a diagram illustrating a region to be measured in a transfer function of a second-order distortion of a nonlinear system when a tap of a dimensional filter is determined.

FIG. 25 is a block diagram showing a distortion removing device according to a fifteenth embodiment of the present invention.

FIG. 26 is a block diagram showing a distortion removing device according to a sixteenth embodiment of the present invention.

FIG. 27 is a block diagram illustrating a multiprocessor according to a seventeenth embodiment of the present invention.

FIG. 28 is a block diagram illustrating a speaker power amplifier according to an eighteenth embodiment of the present invention.

FIG. 29 is a block diagram showing a processing speaker system according to a nineteenth embodiment of the present invention.

FIG. 30 is a block diagram showing a distortion removing apparatus according to a twentieth embodiment of the present invention.

FIG. 31 is a block diagram showing a distortion removing apparatus according to a twenty-first embodiment of the present invention.

FIG. 32 is a block diagram showing a speaker power amplifier according to a twenty-second embodiment of the present invention.

FIG. 33 is a block diagram showing a speaker multiprocessor according to a twenty-third embodiment of the present invention.

FIG. 34 is a block diagram showing a processing speaker system according to a twenty-fourth embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 11 A / D conversion device 12 Frame division device 13 Fourier transformation device 14 Multiplier 15 First storage device 16 Multiplication adder 17 Second storage device 18 Adder 19 Inverse Fourier transformation device 20 Frame synthesis device 21 D / A conversion Device 22 speaker 27 third storage device 50 processing speaker system 60 multiprocessor 10, 70, 90, 110, 130, 170, 210,
250, 260, 300, 310, distortion removal device 71, 91, 111, 131, 171, 211, 25
1,261,301,311 First filter 72,92,112,132,172,212,25
2,262,302,312 Second filter 133 Low pass filter 173 Band pass filter 213 High pass filter 253 Processor

Claims (39)

[Claims] 1. A system for removing distortion in a system connected between a signal source and a signal input of the system, the signal processing being performed on a signal output from the signal source to compensate for a distortion component generated in the system. An apparatus, comprising: a frame dividing unit that divides and outputs a signal output from a signal source by a length N while partially overlapping the signal; and Fourier-transforms a time-domain signal divided by the frame dividing unit. A Fourier transform unit for converting to a domain signal, N first coefficients and N × N second coefficients in the frequency domain
A storage unit that stores the coefficients of the Fourier transform unit, and an arithmetic operation based on the first coefficient and the output signal of the Fourier transform unit, and an arithmetic operation based on the second coefficient and the output signal of the Fourier transform unit. An operation unit that removes a distortion component from an output signal of the conversion unit; an inverse Fourier transform unit that performs an inverse Fourier transform of the output signal of the operation unit to convert the output signal into a time-domain signal; And a frame synthesizing section for sequentially connecting and outputting the sections. 2. A system according to claim 1, wherein said system is connected between a signal source and a signal input section of said system, and performs signal processing for compensating a distortion component generated in said system for a signal output from said signal source. An apparatus, comprising: a frame dividing unit that divides and outputs a signal output from a signal source by a length N while partially overlapping the signal; and Fourier-transforms a time-domain signal divided by the frame dividing unit. Using a Fourier transform unit that converts the signal into a domain signal, a first storage unit that stores N first coefficients in the frequency domain, and an output signal of the Fourier transform unit using the first coefficient. A first multiplier for multiplying the first term on the right side of equation (1); (Where m, m1, and m2 are integer values representing the number of discrete points on the frequency axis, W (m) is the component of the m-th frequency point of the output signal of the distortion removal device in the frequency domain, G1 (M) is the first coefficient, X (m) is the m component of the signal obtained by discretizing the input signal and then transforming it to the frequency domain by Fourier transform, G2 (m1, m2) is the second coefficient, and X (m1) Is the m1 component of the signal obtained by discretizing the input signal and then transforming it to the frequency domain by Fourier transform, X
(M2) represents the m2 component of the signal obtained by discretizing the input signal and then transforming the signal into the frequency domain by Fourier transform. The second term on the right side of (Equation 1) using a second storage unit that stores N × N second coefficients in a frequency domain, and the output signal of the Fourier transform unit. A multiplier and an adder for performing multiplication and addition of: an adder for adding an output signal of the first multiplier and an output signal of the multiplier and an output signal of the adder; A distortion removing apparatus comprising: an inverse Fourier transform unit for converting the output signal into a signal; and a frame combining unit for sequentially connecting and outputting a part of the output signal of the inverse Fourier transform unit. 3. A system for removing distortion in a system, which is connected between a signal source and a signal input of the system and performs signal processing on a signal output from the signal source to compensate for a distortion component generated in the system. An apparatus, comprising: a frame dividing unit that divides and outputs a signal output from a signal source by a length N while partially overlapping the signal; and Fourier-transforms a time-domain signal divided by the frame dividing unit. A Fourier transform unit for converting the impulse response of the N-tap delay device having a delay amount substantially equal to the group delay amount of the first-order impulse response of the system from which the distortion is to be removed; A third storage unit that stores the taps in the frequency domain to be obtained, and a tap stored in the third storage unit that is read and multiplied by an output signal of the Fourier transform unit The first to do the arithmetic
A first storage unit that stores N first coefficients in a frequency domain; and a right side of (Equation 1) using the first coefficient and an output signal of the first multiplier. A second multiplier for multiplying the first term; (Where m, m1, and m2 are integer values representing the number of discrete points on the frequency axis, W (m) is the component of the m-th frequency point of the output signal of the distortion removal device in the frequency domain, G1 (M) is the first coefficient, X (m) is the m component of the signal obtained by discretizing the input signal and then transforming it to the frequency domain by Fourier transform, G2 (m1, m2) is the second coefficient, and X (m1) Is the m1 component of the signal obtained by discretizing the input signal and then transforming it to the frequency domain by Fourier transform, X
(M2) represents the m2 component of the signal obtained by discretizing the input signal and then transforming the signal into the frequency domain by Fourier transform. Using a second storage unit that stores N × N second coefficients in the frequency domain, and using the second coefficient and the output signal of the first multiplier, A multiplier-adder that performs multiplication and addition of two terms; an adder that adds an output signal of the second multiplier and an output signal of the multiplier-adder; and an inverse Fourier transform of the output signal of the adder. A distortion removal apparatus comprising: an inverse Fourier transform unit that converts a signal into a time domain signal; and a frame synthesis unit that sequentially connects and outputs a part of an output signal of the inverse Fourier transform unit. 4. The second storage section stores, among two-dimensional N × N second coefficients represented in a frequency domain, coefficients in a region defined by (Expression 11), 3] The multiplier / adder uses the second coefficient of only the defined area and the output signal of the Fourier transform unit to obtain (Equation 1)
Perform the operation shown in 2). The distortion removing device according to claim 2 or 3, wherein: 5. A processing speaker system equipped with the distortion removing device according to claim 1, wherein the system that generates the distortion is a speaker that reproduces an audio signal. Speaker system. 6. A multiprocessor equipped with the distortion removing device according to claim 1, wherein the system for generating the distortion is a speaker for reproducing an audio signal, and a signal source and the speaker are connected to each other. A multiprocessor inserted between driving amplifiers. 7. The coefficient determining method of the distortion removing apparatus according to claim 2, wherein the first coefficient G1 (m), which is a sequence of N numerical values, is obtained by: The transfer function of the system is measured as a numerical sequence of the number of points N2 in the frequency domain, where N2 ≦
N1 <N, and the numerical sequence in the frequency domain is converted into a numerical sequence with the number of points N2 in the time domain by an inverse Fourier transform. At the end of the numerical sequence in the time domain, N-N2 0 data are added. Is converted to a numerical sequence of the number of points N in the frequency domain by Fourier transform by the Fourier transform, and stored in the storage unit as the first coefficient. In order to obtain the N second coefficients G2 (m1, m2), the transfer function of a second-order system that generates distortion of the system is measured as a numerical array of the number of points N3 × N3 in the frequency domain, where , N3 ≦ N1 <N, and converting the numerical array in the frequency domain into a numerical array of the number of points N3 × N3 in the time domain by two-dimensional inverse Fourier transform; N-N3 pieces of 0 data are added to the final end in both the row direction and the column direction to form an N × N numerical array. The numerical data array having the number of points N × N to which the 0 data is added is a two-dimensional array. A coefficient of the distortion removing apparatus is converted into a numerical array of N × N points in the frequency domain by Fourier transform, and the N × N numerical array is stored in the storage unit as the second coefficient. How to determine. 8. The larger value of the number of points N2 of the transfer function of the primary system of the system and the number of points N3 of one side of the array which is the transfer function of the secondary system of the system is:
The distortion according to claim 7, wherein the tap length N1 is equal to a tap length N1 defining an overlap length (N1-1) of frames in the frame division unit, and the tap length N1 has a relationship of N1 = N / 2. How to determine the coefficient of removal and transfer. 9. A signal which is connected between a signal source and a signal input section of a system and which adds a characteristic of a low-pass filter to a signal output from the signal source and compensates for a distortion component generated in the system. An A / D converter for converting an analog signal output from a signal source into a digital signal, and a one-dimensional convolution with respect to an output signal of the A / D converter. A first filter that performs an operation, a second filter that performs a two-dimensional convolution operation on the digital signal, and an addition that adds an output signal of the first filter and an output signal of the second filter. D / A for converting an output signal of the adder into an analog signal
And m is an integer value representing the number of points on the frequency axis, and m1 and m2 are integer values representing the number of points on the frequency axis, where m = m1 + m2 or m = | m1-m2 |, H1 (m) is a value expressing the transfer characteristic of the first-order system of the system in the frequency domain, and H2 (m1, m2) is the second-order value of the system. Assuming that the transfer characteristics of the harmonic distortion and the intermodulation distortion are values expressed in a two-dimensional frequency domain, the transfer characteristics G1L (m) of the first filter are arbitrarily determined as the characteristics L (m) of the low-pass filter. A characteristic G1 obtained by multiplying a possible first-order transfer characteristic G1 (m).
(M) L (m), and the transfer characteristic G2L (m1, m2) of the second filter
Is a characteristic represented by (Equation 16). A distortion removing device characterized by the above-mentioned. 10. The filter according to claim 1, wherein the second filter has a tap length N × N.
When the number of points on the frequency axis corresponding to the cut-off frequency of the low-pass filter is mc, when mc is equal to or less than N / 4, the second filter: Substantial calculation is performed on taps only in the areas indicated by (Equation 17) and (Equation 18). (Equation 7) The distortion removing device according to claim 9, wherein: 11. The second filter has a tap length N ×
N is a two-dimensional digital filter, and assuming that the number of points on the frequency axis corresponding to the cutoff frequency of the low-pass filter is mc, when mc is larger than N / 4, the second filter: A substantial operation is performed on taps only in the regions shown in (Equation 19) to (Equation 21). (Equation 9) (Equation 10) The distortion removing device according to claim 9, wherein: 12. A signal which is connected between a signal source and a signal input section of the system, adds a characteristic of a band-pass filter to a signal output from the signal source, and compensates for a distortion component generated in the system. An A / D converter for converting an analog signal output from a signal source into a digital signal, wherein the A / D converter outputs a one-dimensional signal to the output signal of the A / D converter. A first filter that performs a convolution operation, a second filter that performs a two-dimensional convolution operation on the digital signal, and an output signal of the first filter and an output signal of the second filter are added. An adder; and a D / A for converting an output signal of the adder into an analog signal.
And m is an integer value representing the number of points on the frequency axis, and m1 and m2 are integer values representing the number of points on the frequency axis, where m = m1 + m2 or m = | m1-m2 |, H1 (m) is a value expressing the transfer characteristic of the first-order system of the system in the frequency domain, and H2 (m1, m2) is the second-order value of the system. Assuming that the transfer characteristics of the harmonic distortion and the intermodulation distortion are values expressed in a two-dimensional frequency domain, the transfer characteristics G1B (m) of the first filter are arbitrarily set to the characteristics B (m) of the bandpass filter. A characteristic G obtained by multiplying the determinable primary transfer characteristic G1 (m).
1 (m) B (m), and the transfer characteristic G2L (m1, m2) of the second filter
Is a characteristic represented by (Equation 24). A distortion removing device characterized by the above-mentioned. 13. The filter according to claim 1, wherein the second filter has a tap length N × N.
The number of points on the frequency axis corresponding to the cut-off frequency on the high frequency side of the band-pass filter is mch, and the number of points on the frequency axis corresponds to the cut-off frequency on the low frequency side of the band-pass filter. Assuming that the number of points on the frequency axis is mcl, when mch is equal to or smaller than N / 4, the second filter performs a substantial operation on taps only in the regions indicated by (Equation 25) and (Equation 26). [Equation 12] (Equation 13) 13. The distortion removing device according to claim 12, wherein: 14. The filter according to claim 1, wherein the second filter has a tap length N × N.
The number of points on the frequency axis corresponding to the cut-off frequency on the high frequency side of the band-pass filter is mch, and the number of points on the frequency axis corresponds to the cut-off frequency on the low frequency side of the band-pass filter. Assuming that the number of points on the frequency axis is mcl, when mch is larger than N / 4, the second filter performs a substantial operation on taps only in the regions indicated by (Expression 27) to (Expression 29). [Equation 14] (Equation 15) (Equation 16) 13. The distortion removing device according to claim 12, wherein: 15. A signal which is connected between a signal source and a signal input section of a system, adds a characteristic of a high-pass filter to a signal output from the signal source, and compensates for a distortion component generated in the system. An A / D converter for converting an analog signal output from a signal source into a digital signal, and a one-dimensional convolution with respect to an output signal of the A / D converter. A first filter for performing an operation, a second filter for performing a two-dimensional convolution operation on the digital signal, and an output signal of the first filter and an output signal of the second filter are added. An adder; and a D / A for converting an output signal of the adder into an analog signal.
A converter, wherein m is an integer value representing the number of points on the frequency axis, and m1 and m2 are integer values representing the number of points on the frequency axis, and m = m1 + m2 or m for the integer value m.
= | M1-m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is the second harmonic of the system. Assuming that the transfer characteristics of the wave distortion and the intermodulation distortion are values expressed in a two-dimensional frequency domain, the transfer characteristics G1F (m) of the first filter can be arbitrarily determined to be the characteristics F (m) of the high-pass filter. Characteristic G1 multiplied by first-order transfer characteristic G1 (m)
(M) F (m), and the transfer characteristic G2H (m1, m2) of the second filter
Is a characteristic represented by (Equation 32). A distortion removing device characterized by the above-mentioned. 16. The method according to claim 16, wherein the second filter has a tap length N × N.
Where the number of points on the frequency axis corresponding to the cutoff frequency of the high-pass filter is mc, the second filter is represented by (Equation 33) to (Equation 35). Perform a substantial operation on taps only in the area. [Equation 19] (Equation 20) The distortion removing device according to claim 15, wherein: 17. A processing speaker system equipped with the distortion removing device according to claim 9, wherein the system that generates the distortion is a speaker that reproduces an audio signal. Processing speaker system. 18. A multiprocessor equipped with the distortion removing device according to claim 9, wherein the system for generating the distortion is a speaker for reproducing an audio signal, and a signal source and the signal source. A multiprocessor inserted between amplifiers for driving speakers. 19. A distortion removal apparatus for a system, which is connected between a signal source and a signal input unit of the system and performs signal processing for compensating a distortion component generated in the system for a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source; a second filter that performs a two-dimensional convolution operation on a signal from the signal source; A low-pass filter to which an output signal of the second filter is input, and an adder that adds the output signal of the first filter and the output signal of the low-pass filter, wherein a cut-off frequency of the low-pass filter is A distortion removing device, wherein the frequency is equal to or lower than the upper limit of the reproduction frequency band of the system. 20. A distortion removal apparatus for a system, which is connected between a signal source and a signal input section of the system and performs signal processing for compensating a distortion component generated in the system for a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source; a second filter that performs a two-dimensional convolution operation on a signal from the signal source; An adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value expressing an input signal from the signal source in a frequency domain is X (m), and m is a frequency. Where m1 and m2 are m = m1 + m2 with respect to the integer value m.
Or m = | m1−m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is the second order of the system. G1 (m) is a value representing the transfer characteristic of the first filter in the frequency domain, and G2 (m1, m2 is a value representing the transfer characteristic of the harmonic distortion and the cross-modulation distortion in the two-dimensional frequency domain. ) Is a value expressing the transfer characteristic of the secondary system of the second filter in the frequency domain, and mc is an integer value corresponding to a cutoff frequency on a higher frequency side of the transfer characteristic of the primary system of the system. Then, the second filter is a two-dimensional digital filter having a tap length of N × N, and has a transfer characteristic G2 (m1, m2) for the input signal X (m) as a characteristic represented by (Equation 9). And (Equation 36) Region represented Te only the input signal X (m) is the convolution operation and output,
Block areas other than (Equation 36). (Equation 22) A distortion removing device characterized by the above-mentioned. 21. The second filter substantially performs a convolution operation only in a region represented by (Expression 37). The distortion removing device according to claim 20, wherein: 22. The one-dimensional tap of the first filter,
And when setting a two-dimensional tap of the second filter, the transfer characteristics H1 (m) and 2 of the primary system of the system
The transfer function is measured only in the region represented by (Expression 38) in the component of the transfer characteristic H2 (m1, m2) of the following system. 22. The distortion removing device according to claim 21, wherein: 23. A distortion removal apparatus for a system, which is connected between a signal source and a signal input unit of the system and performs signal processing for compensating a distortion component generated in the system for a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source; a second filter that performs a two-dimensional convolution operation on a signal from the signal source; A band-pass filter to which an output signal of the second filter is input, and an adder for adding an output signal of the first filter and an output signal of the band-pass filter, and a low-pass side of the band-pass filter. The cutoff frequency is
The frequency is equal to or higher than the lower limit of the reproduction frequency band of the system, and the high-side cutoff frequency of the bandpass filter is
A distortion removing apparatus, wherein the frequency is equal to or lower than a reproduction frequency band upper limit of the system. 24. A distortion removal apparatus for a system, which is connected between a signal source and a signal input section of the system and performs signal processing for compensating a distortion component generated in the system for a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source; a second filter that performs a two-dimensional convolution operation on a signal from the signal source; An adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value expressing an input signal from the signal source in a frequency domain is X (m), and m is a frequency. Where m1 and m2 are m = m1 + m2 with respect to the integer value m.
Or m = | m1−m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is the second order of the system. G1 (m) is a value representing the transfer characteristic of the first filter in the frequency domain, and G2 (m1, m2 is a value representing the transfer characteristic of the harmonic distortion and the cross-modulation distortion in the two-dimensional frequency domain. ) Is a value expressing the transfer characteristic of the second filter in a frequency domain, and mc is an integer value corresponding to a cutoff frequency on a higher frequency side of a transfer characteristic of a primary system of the system. Is a two-dimensional digital filter having a tap length N × N, wherein the transfer characteristic G2 (m1, m2) for the input signal X (m) is a characteristic represented by (Equation 9), and (Equation 39) Represented by) Region only the input signal X (m) of the convolution operation to output that,
Block areas other than (Equation 39) (Equation 26) A distortion removing device characterized by the above-mentioned. 25. The second filter substantially performs a convolution operation only in a region represented by (Expression 40). The distortion removing device according to claim 24, wherein: 26. The one-dimensional tap of the first filter,
And when setting a two-dimensional tap of the second filter, the transfer characteristics H1 (m) and 2 of the primary system of the system
The transfer function is measured only in the region represented by (Expression 41) in the component of the transfer characteristic H2 (m1, m2) of the following system. 26. The distortion removing device according to claim 25, wherein: 27. A distortion removal apparatus for a system, which is connected between a signal source and a signal input unit of the system and performs signal processing for compensating a distortion component generated in the system for a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source; a second filter that performs a two-dimensional convolution operation on a signal from the signal source; A high-pass filter to which the output signal of the second filter is input, and an adder that adds the output signal of the first filter and the output signal of the high-pass filter, wherein the cut-off frequency of the high-pass filter is A distortion removing device having a frequency mc equal to or higher than a lower limit of a reproduction frequency band of a system. 28. A distortion removing apparatus for a system, which is connected between a signal source and a signal input section of the system and performs signal processing for compensating a distortion component generated in the system for a signal output from the signal source. A first filter that performs a one-dimensional convolution operation on a signal from the signal source; a second filter that performs a two-dimensional convolution operation on a signal from the signal source; An adder for adding an output signal of the first filter and an output signal of the second filter, wherein a value expressing an input signal from the signal source in a frequency domain is X (m), and m is a frequency. Where m1 and m2 are m = m1 + m2 with respect to the integer value m.
Or m = | m1−m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is the second order of the system. G1 (m) is a value representing the transfer characteristic of the first filter in the frequency domain, and G2 (m1, m2 is a value representing the transfer characteristic of the harmonic distortion and the cross-modulation distortion in the two-dimensional frequency domain. ) Is a value expressing the transfer characteristic of the second filter in a frequency domain, and mc is an integer value corresponding to a cutoff frequency on a higher frequency side of a transfer characteristic of a primary system of the system. Is a two-dimensional digital filter having a tap length N × N, wherein the transfer characteristic G2 (m1, m2) for the input signal X (m) is a characteristic represented by (Expression 9), and (Expression 42) Represented by) Region only the input signal X (m) of the convolution operation to output that,
Block areas other than (Equation 42) [Equation 30] A distortion removing device characterized by the above-mentioned. 29. The second filter substantially performs a convolution operation only in a region represented by (Expression 43). 29. The distortion removing device according to claim 28, wherein: 30. The one-dimensional tap of the first filter,
And when setting a two-dimensional tap of the second filter, a transfer characteristic H1 of a primary system of the system is set.
The transfer function is measured only in the region represented by (Equation 44) in the component of (m) and the transfer characteristic H2 (m1, m2) of the second-order system. 30. The distortion removing device according to claim 29, wherein: 31. The method according to claim 19,20,23,24,27,
29. A processing speaker system equipped with the distortion removal device according to any one of claims 28, wherein the system that generates the distortion is a speaker that reproduces an audio signal. 32. The method of claim 19, 20, 23, 24, 27,
28. A multiprocessor equipped with the distortion removal device according to any one of claims 28 to 28, wherein the system that generates the distortion is a speaker that reproduces an audio signal, and is inserted between a signal source and an amplifier that drives the speaker. A multiprocessor characterized by the above. 33. A processor in front of the system, inserted between a signal source and a signal input of the processor,
What is claimed is: 1. A distortion removing device that performs signal processing of distortion component compensation occurring in the system, comprising: a first filter that performs a one-dimensional convolution operation on a signal from the signal source; A second filter that performs a two-dimensional convolution operation, and an adder that adds the output signal of the first filter and the output signal of the second filter. Let X (m) be a value expressed in the frequency domain, m be an integer value representing a frequency point, and m1 and m2 be m = m1 + m2 with respect to the integer value m.
Or m = | m1−m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is the second order of the system. The transfer characteristics of the harmonic distortion and the intermodulation distortion are represented in a two-dimensional frequency domain, E (m) is the value representing the transfer characteristics of the processor in the frequency domain, and G1 (m) is the first Let G2 (m1, m2) be a value expressing the transfer characteristic of the second filter in the frequency domain, and assume that G2 (m1, m2) is a value expressing the transfer characteristic of the second filter in the frequency domain. N, a two-dimensional digital filter having a two-dimensional transfer characteristic G2 (m1, m2) represented by (Equation 48).
(M) is convoluted and output. A distortion removing device characterized by the above-mentioned. 34. A detecting unit for detecting a transfer characteristic E (m) of the processor, and a transfer characteristic G2 (m1, m2) of the second filter using the detected transfer characteristic E (m). 34. The apparatus according to claim 33, further comprising: a tap updating unit for updating.
3. The distortion removing device according to 1. 35. A processor in front of the system, inserted between a signal source and a signal input of the processor,
What is claimed is: 1. A distortion removing apparatus for performing signal processing of distortion component compensation generated by said system and said processor, comprising: a first filter for performing a one-dimensional convolution operation on a signal from said signal source; A second filter that performs a two-dimensional convolution operation on the signal; and an adder that adds an output signal of the first filter and an output signal of the second filter. Let X (m) be a value representing the input signal in the frequency domain, m be an integer value representing a frequency point, and m1 and m2 be m = m1 + m2 with respect to the integer value m.
Or m = | m1−m2 |, H1 (m) is a value expressing the transfer characteristic of the primary system of the system in the frequency domain, and H2 (m1, m2) is the second order of the system. A1 (m) is a value expressing the transfer characteristic of the first-order system of the processor in the frequency domain, and A2 (m1 is a value expressing the transfer characteristic of the harmonic distortion and the intermodulation distortion in the two-dimensional frequency domain. , M2) is a value expressing the transfer characteristic of the secondary system of the processor in the frequency domain, G1 (m) is a value expressing the transfer characteristic of the first filter in the frequency domain, and G2 (m1, m2) ) Is a value expressing the transfer characteristic of the second filter in the frequency domain, the second filter is a two-dimensional digital filter having a tap length N × N, and is represented by (Expression 52). Dimensional transfer characteristics G (M1, m2) in the input signal X
(M) is convoluted and output. A distortion removing device characterized by the above-mentioned. 36. A detection unit for detecting a transfer characteristic A1 (m) of the processor, a storage unit for storing a transfer characteristic A2 (m1, m2) of the distortion of the processor measured in advance, and an output of the detection unit. And a transfer signal G2 of the second filter.
36. The distortion removing apparatus according to claim 35, further comprising a tap updating unit that updates (m1, m2). 37. A multiprocessor equipped with the distortion removing device according to claim 33, wherein the system that generates the distortion is a speaker that reproduces an audio signal, and a signal source and an amplifier that drives the speaker. A multiprocessor characterized by being inserted between. 38. An amplifier equipped with the distortion removing device according to claim 33, wherein the system for generating the distortion is a speaker for reproducing an audio signal, and the speaker is driven. Amplifier. 39. A processing speaker system equipped with the distortion removing device according to claim 33 or 35, wherein the system that generates the distortion is a speaker that reproduces an audio signal.