JPS63281508A - Tone control device - Google Patents

Abstract

PURPOSE:To correct a phase frequency characteristic to express the characteristic of a system with a group delay characteristic of a speaker, etc., by integrating a signal to be inputted to a phase input means with a phase integrating means. CONSTITUTION:A signal from an amplitude input means 11 is directly inputted to a transfer function arithmetic means 14 and a signal from a phase input means 12 is inputted through a phase operating means 13 to build in an integrating means 303 to the means 14. After that, a transfer function from here is reverse-Fourier-transformed by a reverse-Fourier-transforming means 15, a transversal filter coefficient is obtained and this is sent through a setting means 16 to a transversal filter 17. After that, an input signal from a signal input means 18 is passed through the filter 17 and a signal whose phase characteristic is corrected is outputted from a signal output means 19. Thus, for a phase input, a group delay characteristic is integrated by a frequency and a phase frequency characteristic is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a transversal filter (hereinafter referred to as l'IR) that realizes arbitrary amplitude frequency characteristics and phase frequency characteristics.
This invention relates to a sound quality adjustment device using a filter (called a filter).

2. Description of the Related Art In recent years, along with the digitalization of audio equipment, there has been a demand for the development of equalizers using FIR filters.

However, conventionally, it has not been possible to independently control the amplitude frequency characteristic and the phase frequency characteristic using one FIR filter.

FIG. 8 shows a block diagram of a conventional sound quality adjustment device using an FIR filter that can control only amplitude frequency characteristics. In FIG. 8, 1 is an amplitude input means for inputting an arbitrary amplitude-frequency characteristic IH1, and 6 is a transfer function using the input amplitude-frequency characteristic as a transfer function, and obtains a filter coefficient by performing inverse 7-lier transform on this transfer function. Inverse Fourier transform means, 6 is a setting means for setting the determined filter coefficients in the FIR filter, and 7 is the actually given amplitude frequency characteristic? 8 is a signal input means for inputting a signal to the FIR filter, and 9 is a signal output means for outputting a result processed by the FIR filter 7.

The desired amplitude frequency characteristic IH-1 is input by the amplitude input means 1. FIG. 9 shows an example of input amplitude frequency characteristics. In FIG. 9A, the input point is indicated by a black circle. However, the characteristic for ω=π-2π is created by folding the input characteristic for ω=0-π as shown in FIG. 9B.

Next, in the inverse Fourier transform means 6, the transfer function H = I
Hu)1 (1) By performing inverse Fourier transform on H(→, the filter coefficient (impulse response to H(4)) can be obtained.

The inverse Fourier transform is performed as shown in the following equation.

h(n)=1/NxΣHfu) x @ '<17"
-=i)(ω=2xπ/Nxk width n≦N-1)(
h(n) determined by equation 2) is set as a filter coefficient in the FIR filter 7 by the setting circuit 6, and the amplitude frequency characteristic given here is realized. The phase frequency characteristic becomes a linear phase by giving a transfer function using equation (1).

Problems to be Solved by the Invention However, in the conventional example shown in FIG. 8, although arbitrary amplitude frequency characteristics can be achieved as mentioned at the beginning, the phase frequency characteristics are uniquely determined by the number of tap coefficients of the FIR filter. The disadvantage is that the linear phase is fixed and the phase frequency characteristics cannot be set arbitrarily. Furthermore, in order to realize the amplitude and phase characteristics of a certain circuit, it is necessary to measure the amplitude and phase characteristics of the circuit and input them using amplitude and phase input means. Furthermore, it was not possible to easily input phase and amplitude characteristics obtained by external calculation means.

In view of the above problems, the present invention provides an FIR that allows arbitrary amplitude frequency characteristics and arbitrary phase frequency characteristics to be set independently.
This is a sound quality adjustment device using a filter, and by analyzing the phase and amplitude characteristics of the input signal, it is possible to use the input means to obtain FIR filter characteristics that are the same as those of a circuit that has the same or opposite amplitude and phase characteristics as the input signal. The present invention provides a sound quality adjustment device using an FIR filter that can be realized without inputting amplitude and phase characteristics.

Means for Solving the Problems In order to achieve the above object, the present invention provides an amplitude input means for inputting an arbitrary amplitude frequency characteristic, and a means for inputting an arbitrary amplitude frequency characteristic, and inputting means for inputting an arbitrary amplitude frequency characteristic, and inputting a phase characteristic, a group delay characteristic, an amplitude characteristic, or a resonance condition to obtain a phase frequency characteristic. A phase input means for inputting data, a phase calculation means for calculating a phase frequency characteristic based on the data input by the phase input means, and a transfer function is calculated using the input amplitude frequency characteristic and the phase frequency characteristic determined by the calculation. A transfer function calculating means to obtain, an inverse Fourier transform means to obtain an inno(Russian response) for the transfer function calculated by the transfer function calculating means, and a setting for setting the impulse response obtained by the inverse Fourier transform to a transversal filter as a filter coefficient. means, a transno filter for realizing a filter with set coefficients, a signal input means for inputting a signal to the transno filter, and a transno filter for adjusting the sound quality. The phase calculating means calculates the phase frequency characteristic by integrating the group delay characteristic inputted by the phase inputting means by the frequency. The phase frequency characteristic is calculated based on the resonance frequency, resonance sharpness, and resonance type data.Alternatively, the phase frequency characteristic is calculated from the Hilbert transform relationship from the amplitude characteristic input by the phase input means. It has become.

Operation The present invention is effective in correcting the phase frequency characteristics of a speaker, etc., whose system characteristics are expressed by group delay characteristics, due to the above-described configuration. Furthermore, by calculating the phase frequency characteristic from the Hilbert transform relationship, it is possible to obtain a phase frequency characteristic that accurately approximates a system with a certain phase frequency characteristic. It is easy to approximate a system that performs this and to correct the phase-frequency characteristics of such a system.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of a sound quality adjustment device in an embodiment of the present invention.

In FIG. 1, 11 is an amplitude input means for inputting desired amplitude frequency characteristics, 12 is a phase input means for inputting data necessary to calculate a desired phase frequency characteristic, and 13 is input by the phase input means 12. It has an integrating means 303 that integrates the group delay characteristic obtained by the frequency, and thereby obtains a phase frequency characteristic. A transfer function calculation means 16 calculates a transfer function having frequency characteristics, an inverse Fourier transform means 16 performs an inverse Fourier transform on the transfer function obtained by the transfer function calculation means 14, and a filter 16 filters the impulse response obtained by the inverse Fourier transform means 15. Setting means for setting coefficients; 17 is an FIR filter that realizes the actually set amplitude-phase-frequency characteristics;
8 is a signal input means for inputting a signal to the FIR filter 17, and 19 is a signal output means for outputting a result processed by the FIR filter 17.

The operation of this embodiment will be described below with reference to the drawings.

In the amplitude input means 11, a desired amplitude frequency characteristic IH(4)1 of ω=0 to 2π is set. In addition, as a setting method, once the desired amplitude frequency characteristic IH(4)1 of ω=0 to π is set in the amplitude input means 11, this input amplitude frequency characteristic is folded around ω=π. Alternatively, an amplitude frequency characteristic of ω=π to 2π may be created.

Next, the phase input means 12 inputs data used in the calculation of the phase frequency characteristic in the phase calculation means 13 to ω=0 to 2.
It is input in the frequency range of π, and the phase calculation means 1
3 determines the phase frequency characteristic in the frequency range of ω=0 to 2π based on this. Furthermore, even in this case,
The phase input means 12 inputs data in the frequency range of ω=0 to π, and based on this, the phase calculation means 13 inputs data in the frequency range of ω=0 to π.
The amplitude frequency characteristic of ω=π to 2π may be created by finding the phase frequency characteristic in the frequency range of π, and then reversing the sign of this phase frequency characteristic and folding it back around ω=π.

The transfer function calculation means 14 calculates the transfer function using the amplitude and phase frequency characteristics in the frequency range of ω=Q to 2π.

The transfer function calculated by the transfer function calculating means 14 is inversely Fourier transformed by the inverse Fourier transforming means 16 to find an FIR filter coefficient that satisfies both the amplitude and phase characteristics.
By setting a signal to the FIR filter 17 using the signal input means 18 and outputting the signal output from the FIR filter 17 to the outside using the signal output means 19, the sound quality that satisfies both the amplitude and phase characteristics is achieved. A regulating device is realized.

As described above, according to this embodiment, by providing the integration means 303 that integrates the group delay characteristic inputted in the phase manual means 12 with respect to the frequency, it is possible to input the group delay characteristic obtained by differentiating the phase with respect to the frequency. Therefore, it is particularly effective when correcting the phase frequency characteristics of a speaker, etc. whose system characteristics are expressed by group delay characteristics.

FIG. 2 shows a block diagram of a sound quality adjustment device according to a second embodiment of the present invention.

Since the group delay characteristic input from the phase input means 12 of this embodiment is an arbitrary frequency characteristic, the deviation from a certain value (
distortion), making it impossible to accurately calculate the phase frequency characteristics that can actually be achieved. Therefore, the average value subtraction calculation means 302
The average value of the integral value over all frequencies of the input group delay characteristic is calculated, the input group delay characteristic is rewritten as the deviation from this average value, and the integrator 303 calculates the value of the corrected group delay characteristic. Determine the phase frequency characteristics from the integral value. By performing such operations, it becomes possible to obtain more accurate phase frequency characteristics.

FIG. 3 shows a block diagram of a sound quality adjustment device according to a third embodiment of the present invention.

In FIG. 3, reference numeral 304 denotes a resonance phase conversion means that calculates a phase frequency characteristic based on data on the resonance frequency, resonance sharpness, and resonance type inputted from the phase input means 12&C.

This resonance phase conversion means 5o41ri calculates a function as shown in equation (4) to obtain the phase frequency characteristic. ←) What is shown in the formula represents the phase frequency characteristic of a low-pass filter (corresponding to a type of resonance) using a two-hokage active filter, and the resonance frequency fc and resonance sharpness ζ are given by formula (c). It is.

(Phase) = -tan-' wC2(R4+R2)/
(1-w2C1C2R,R2)・・・・・・(4) f0=1〆[Komi East 7koT・・・・・・←）
ζ=02(R4+R2)Z "Insect summer luck maq..."
(@(W: angular frequency, R4, R2: resistance value, C1, C2
: capacitor value) Figures 4A and 4B show a diagram of a low-pass filter using a secondary active filter configured with an operational amplifier and a transistor, and Figure 4C shows the characteristics when the sharpness of resonance in this resonant system is varied. Show the diagram. However, the amplitude-frequency characteristics shown in these four figures are amplitude-frequency characteristics corresponding to the phase-frequency characteristics with respect to the sharpness of each resonance of the low-pass filter by the secondary active filter, and the amplitude-frequency characteristics in this example are only the amplitude-frequency characteristics. This is input by the input means 11.

Although an example is shown in which equation (3) is used as the function for calculating the phase frequency characteristic, any function may be used as long as it is a function for calculating the phase frequency characteristic of the low-pass filter. Although the type of resonance is shown as low-pass, it may also be high-pass or band-pass, or it may be a function that approximates the phase frequency characteristics of a speaker or the like.

As described above, the resonance frequency, the sharpness of resonance, and the type of resonance are input by the phase input means 12, and the resonance phase conversion means 3
By calculating the phase frequency characteristic at φ in 04, it becomes possible to easily obtain a phase frequency characteristic that accurately approximates a system having a certain phase frequency characteristic.

FIG. 5A shows a professional diagram of a sound quality adjustment device according to a fourth embodiment of the present invention.

In this embodiment, after the resonance phase conversion means 304, a differentiating means 301 that differentiates the phase with respect to frequency, an average value subtracting means 302 that calculates the average value of the results of the differentiating means 301 and subtracts the average value from the result of the differentiating means 301, and an average An integrating means 303 for integrating the result of the value calculating means 302 with respect to frequency is connected.

In this embodiment, the phase frequency data is inputted in the phase input means 12, while the resonance frequency, resonance sharpness, and resonance type explained in the previous embodiment are inputted from the amplitude input means 11. Based on the resonant phase conversion means 30
4 differs in that the phase frequency characteristics are determined,
According to the phase calculation means 13 of this embodiment, the phase input means 1
Even if the phase frequency characteristic obtained using the data input in step 2 changes greatly as shown in Figure 5B, the above configuration allows the phase frequency to be changed with little phase change as shown in Figure 5C. Characteristics can be obtained and highly accurate filter coefficients can be found.

FIG. 5 shows a block diagram of a sound quality adjustment device according to a fifth embodiment of the present invention.

In FIG. 5, reference numeral 305 is a Hilbert phase characteristic calculation means for calculating a phase frequency characteristic that causes the minimum phase shift with respect to the amplitude frequency characteristic from the Hilbert transform relationship from the amplitude characteristic inputted by the phase input means 12. With the above configuration, in this embodiment, the Hilbert phase characteristic calculation means 305 can find the phase frequency characteristic with the minimum phase shift with respect to the amplitude frequency characteristic inputted by the phase input means 12. The advantage is that it is easy to approximate a system in which a certain system exhibits a minimum phase shift and to correct the phase frequency characteristics of such a system.

FIG. 7 shows a professional diagram of the sound quality adjustment device in the embodiment of FIG. 5 of the present invention.

This embodiment has a lid configuration in which a differentiation means 301, an average value subtraction operation means 302, and an integration means 303 are connected after the Hilbert phase characteristic calculation means 305 described in the previous embodiment.

In this embodiment, while the phase frequency data is inputted to the phase input means 12, the amplitude frequency characteristic explained in the previous embodiment is inputted from the amplitude input means 11, and based on this, the Hilbert phase The difference is that the phase frequency characteristic is obtained in the characteristic calculation means 305, and the same effects as in the previous embodiment can be obtained.

Effects of the Invention As described above, according to the present invention, there is provided an amplitude input means for inputting arbitrary amplitude frequency characteristics, and inputting data of phase characteristics, group delay characteristics, amplitude characteristics, or resonance conditions to obtain phase frequency characteristics. A phase input means, a phase calculation means for calculating a phase frequency characteristic based on the data input by the phase input means, and a transfer function calculation for calculating a transfer function from the input amplitude frequency characteristic and the phase frequency characteristic determined by the calculation. means, inverse Fourier transform means for obtaining an impulse response to the transfer function calculated by the transfer function calculation means, setting means for setting the impulse response obtained by the inverse Fourier transform as a filter coefficient in the transversal filter; a transversal filter for realizing a coefficient filter; a signal input means for inputting a signal into the transversal filter; and a signal output means for outputting a signal whose sound quality has been adjusted by the transversal filter; The phase calculation means corrects the phase frequency characteristics of a speaker or other device whose system characteristics are expressed by the group delay characteristics, by integrating the group delay characteristics input by the phase input means by frequency and calculating the phase frequency characteristics. It is effective in some cases.

In addition, the phase calculation means calculates the phase frequency characteristic based on the data regarding resonance, so that it is possible to easily obtain a phase frequency characteristic that accurately approximates a system having a well-defined phase frequency characteristic. can.

In addition, the phase calculation means calculates the phase frequency characteristics from the Hilbert transform relationship based on the amplitude characteristics input by the phase input means, thereby approximating a system or a system that performs a minimum phase shift. The phase frequency characteristics of a system can be easily corrected.

[Brief explanation of drawings]

Figure 4 A and B are circuit diagrams of the low-pass filter, Figure 4 C is the characteristic diagram, Figure 5 A is the professional diagram of the fourth embodiment, Figure 5 B, The CF1% sex diagram, Figures 5 and 7 are the 5. FIG. 8 is a block diagram of a conventional sound quality adjustment device, and FIGS. 9A and 9B are characteristic diagrams showing the same-person power state. 11... Amplitude input means, 12... Phase input means, 13-... Phase calculation means, 14...
- Transfer function calculation means, 16... Inverse Fourier transform means, 16... Setting means, 17... Transversal filter, 18... Signal input means,
19... Signal output means, 301... Differentiation means, 302... Average value subtraction calculation means, 30
3...Integration means, 304...Resonance phase conversion means, 305.306...Hilbert phase characteristic calculation means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 2 鵡a - 勺 sword 1 1 - V Hosu family mi ward - υ) grudge 5th figure (B)

Claims (6)

[Claims] (1) An amplitude input means for inputting arbitrary amplitude frequency characteristics, a phase input means for inputting data on phase characteristics, group delay characteristics, amplitude characteristics, or resonance conditions in order to obtain phase frequency characteristics; a phase calculation means for calculating a phase frequency characteristic based on input data; a transfer function calculation means for calculating a transfer function from the input amplitude frequency characteristic and the phase frequency characteristic determined by the calculation; an inverse Fourier transform means for obtaining an impulse response to the calculated transfer function; a setting means for setting the impulse response obtained by the inverse Fourier transform as a filter coefficient in a transversal filter; and the transformer for realizing a filter with the set coefficients. the transversal filter and the signal to the transversal filter.
The phase calculation means includes a signal input means for inputting a signal into a filter, and a signal output means for outputting a signal whose sound quality has been adjusted by the transversal filter, and the phase calculation means converts the group delay characteristic inputted by the phase input means into a frequency. A sound quality adjustment device characterized in that a phase frequency characteristic is calculated by integrating with . (2) The phase calculation means is an integration means for calculating the average value of the group delay frequency characteristic inputted by the phase inputting means and integrating the result of subtracting the average value from the group delay frequency characteristic inputted by the phase inputting means by frequency. The sound quality adjustment device according to claim 1, characterized by comprising:. (3) amplitude input means for inputting arbitrary amplitude frequency characteristics; phase input means for inputting data on phase characteristics, group delay characteristics, amplitude characteristics, or resonance conditions to obtain phase frequency characteristics; a phase calculation means for calculating a phase frequency characteristic based on input data; a transfer function calculation means for calculating a transfer function from the input amplitude frequency characteristic and the phase frequency characteristic determined by the calculation;
an inverse Fourier transform means for calculating an impulse response to the transfer function calculated by the transfer function calculation means; a setting means for setting the impulse response obtained by the inverse Fourier transform as a filter coefficient in a transversal filter; The transversal filter realizes a filter, a signal input means for inputting a signal to the transversal filter, and a signal output means for outputting a signal whose sound quality has been adjusted by the transversal filter, A sound quality adjustment device characterized in that the calculation means includes a resonance phase conversion means for calculating a phase frequency characteristic based on the data of the resonance frequency, the sharpness of resonance, and the type of resonance inputted by the phase input means. (4) The phase calculation means includes a resonance phase conversion means that calculates a phase frequency characteristic based on the resonance frequency, resonance sharpness, and resonance type data inputted by the phase input means, and further includes the resonance phase conversion means. a differentiating means for differentiating the phase frequency characteristic determined by the frequency, an average value subtraction calculation means for calculating an average value of the differential results obtained by the differentiating means and subtracting the average value from the differential result, and the average value subtracting means 4. The sound quality adjustment device according to claim 3, further comprising an integrating means for integrating the result of . (5) amplitude input means for inputting arbitrary amplitude frequency characteristics; phase input means for inputting data on phase characteristics, group delay characteristics, amplitude characteristics, or resonance conditions to obtain phase frequency characteristics; a phase calculation means for calculating a phase frequency characteristic based on input data; a transfer function calculation means for calculating a transfer function from the input amplitude frequency characteristic and the phase frequency characteristic determined by the calculation; an inverse Fourier transform means for obtaining an impulse response to the calculated transfer function; a setting means for setting the impulse response obtained by the inverse Fourier transform as a filter coefficient in a transversal filter; and the transformer for realizing a filter with the set coefficients. the transversal filter and the signal to the transversal filter.
It comprises a signal input means for inputting to a filter, and a signal output means for outputting a signal whose sound quality has been adjusted by the transversal filter, and the phase calculation means calculates a Hilbert transform from the amplitude characteristic input by the phase input means. A sound quality adjustment device comprising Hilbert phase characteristic calculation means for calculating phase frequency characteristics from a relationship. (6) The phase calculation means includes a differentiating means for differentiating the phase frequency characteristic obtained by the Hilbert phase characteristic calculation means with respect to frequency, which calculates the phase frequency characteristic from the Hilbert transform relationship from the amplitude characteristic input by the phase input means; It is characterized by comprising an average value subtraction calculation means for calculating the average value of the differentiation results obtained by the differentiation means and subtracting the average value from the differentiation result, and an integration means for integrating the result of the average value calculation subtraction means with respect to frequency. A sound quality adjustment device according to claim 5.