JPH04103795U - digital channel divider - Google Patents

Abstract

(57) [Summary] [Purpose] Regarding the overall transmission frequency characteristics of each channel,
The object of the present invention is to obtain a digital channel divider that simultaneously realizes flattening of amplitude characteristics and linearization of phase frequency characteristics, and enables faithful transmission and faithful reproduction of acoustic signals of each channel. [Structure] The digital channel divider of this invention connects multiple filters in parallel that can arbitrarily set desired transmission frequency characteristics for digital input signals, and outputs the signals output from each filter independently. The configuration includes a calculation means for calculating a time-series impulse response based on inverse characteristics for flattening the amplitude characteristics and linearizing the phase frequency characteristics of the overall transmission frequency characteristics of each channel, and an output by the calculation means. A real-time processing digital filter is provided which uses the time-series impulse response obtained as a filter coefficient and convolves the filter coefficient with a digital input signal.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention is applicable to digital channel devices used in audio systems, for example. It is about Ida.

0002

[Conventional technology]

Conventionally, for example, multi-channel speakers that use a combination of multiple speakers dedicated to frequency bands have been used. In a way-type speaker system, the structure consists of a coil and a capacitor. The method using the LC network that is created and the method for each frequency band (channel) A multi-amplifier system using a dedicated channel divider is adopted. LCne Channel dividers used in networks and multi-amplifier systems operate in the audio frequency range. The frequency range is divided into several necessary frequency bands, and a speaker dedicated to the corresponding frequency band is created. It has the function of supplying an acoustic signal to the car.

By the way, in the multi-amplifier system, progress has been made in the digitalization of channel dividers composed of electronic circuits. FIG. 1 is an embodiment of the channel divider disclosed in Utility Model No. 2-6673, and is a block diagram showing an example of a speaker system using the multi-amplifier method described above using a digital method. In the figure, 2 _{, 2 1} , 2 ₂ , ... 2 _n are multiple power amplifiers, 3, 3 ₁ , 3 ₂ , ... 3 _n are multiple speaker units, and 4 is a channel divider (frequency band division circuit). ), and is composed of a plurality of linear phase FIR type filters 4 ₁ , 4 ₂ , . . . 4 _n . 4 _{1 1} , 4 ₂₂ , . . . 4 _nn are a plurality of filter coefficient variable devices 5, 5, each of which is an arithmetic means for providing filter coefficients for giving the linear phase FIR type filter a desired frequency band division characteristic. ₁ , 5 ₂ , . . . 5 _n are a plurality of D/A conversion circuits.

0004 In the above multi-way speaker system, the digital signal input is is applied to the channel divider 4, and the linear phase FIR type filter 4₁ ,4₂ ,...4_n and a filter coefficient variable device 4 for providing desired frequency band division characteristics.₁₁,4 _{twenty two} ,...4_nnis convolved with the filter coefficients. Next, the linear phase FIR Ruta 4,4₁ ,4₂ ,...4_n The output of each D/A converter 5, 5₁ ,5₂ ,...5_n It is converted into an analog signal by the power amplifier 2, 2.₁ ,2₂ ， ...2_n is amplified to a predetermined level by speaker units 3, 3.₁ ,3₂ ， ...3_n and converted into sound.

[0005]

[Problem that the idea aims to solve]

The multi-way speaker system described above uses linear phase FIR type filters 4, _{4 1} , 4 ₂ , ... 4 _n as channel dividers, so although the linear phase characteristics are maintained in the channel divider section, the speaker Since the sound pressure frequency characteristics of the unit generally do not exhibit a linear phase, the finally obtained sound pressure characteristics cannot always have a linear phase. As a result, the waveform of the reproduced sound is distorted, making it difficult to reproduce the sound faithfully.

[0006] This invention was made to solve the above problems, and each channel Simultaneously flatten the amplitude characteristics and linearize the phase frequency characteristics of the overall transmission frequency characteristics of A digital device that enables faithful transmission and faithful reproduction of audio signals for each channel. The purpose is to obtain a channel divider.

[0007]

[Means to solve the problem]

The digital channel divider according to the present invention has a total transmission frequency of each channel. A special feature that simultaneously flattens the amplitude characteristics of the wave number characteristics and linearizes the phase frequency characteristics. An inverse filter for gender correction is provided.

[0008]

[Effect]

The digital channel divider according to the present invention has a total transmission frequency of each channel. It is possible to flatten the amplitude characteristic of the wave number characteristic and linearize the phase frequency characteristic, so the waveform Realizes faithful transmission and faithful reproduction of audio signals without distortion.

[0009]

【Example】

Figure 1 shows the digital channel divider according to the present invention used in a multi-amplifier system. 1 is a block diagram showing an example of use in a car system. In Figure 1 mark 2, 2₁ ,2₂ ,...2_n is a power amplifier, 3,3₁ ,3₂ ,...3_n teeth a speaker unit; 10 is a digital channel divider according to the present invention; 4; 4₁ ,4₂ ,...4_n are the component frequencies of the digital channel divider 10. A multi-band dividing circuit 7 is a component of the digital channel divider 10, and each Flattening the amplitude characteristics of the overall transmission frequency characteristics of the channel and directing the phase frequency characteristics Inverse filter for characteristic correction to realize linearization, 7₁ ,7₂ ,…7_n is characteristic correction FIR filter for characteristic correction, 7, which is a component of the inverse filter 7 for₁₁,7_{twenty two},…7 _nn is an inverse filter coefficient generation circuit, 5,5₁ ,5₂ ,...5_n is a digital signal. This is a D/A conversion circuit for converting into analog signals.

0010 In FIG. 1, a digital input signal is first led to a frequency band division circuit 4. In FIG. The frequency band division circuit 4 uses digital filters such as FIR filters and IIR filters. The signal is divided into desired frequency bands by a filter.

[0011] The output signal of the frequency band division circuit 4 is then input to the characteristic correction inverse filter 7. Ru. In the characteristic correction inverse filter 7, the characteristic correction FIR filter 7₁ ,7₂ ,…7 _n Accordingly, the output signal from the frequency band division circuit 4 and the inverse filter coefficient generation circuit 7 ₁₁ ,7_{twenty two},…7_nnis convolved with the coefficient data in real time.

Here, the coefficient data of the inverse filter coefficient generation circuits 7 ₁₁ , 7 _{22 ,} . Set to coefficient data that gives the inverse characteristics of the overall transmission characteristics excluding.

In this way, the digital signal that has been corrected in advance by the characteristic correction inverse filter 7 is then converted into an analog signal by the D/A conversion circuits 5, _{5 1} , 5 ₂ , . _. . , 2 ₁ , 2 ₂ , . . . 2 _n to the speaker units 3, 3 ₁ , 3 ₂ , . . . 3 _n . In the speaker units 3, _{3 1} , 3 ₂ , ... 3 _n , a convolution operation is performed between the corrected analog signal and the impulse response of the speaker unit, and the characteristics finally obtained cancel each other out, resulting in a sound pressure It becomes flat and has a phase straight line, realizing faithful transmission and reproduction of acoustic signals. Note that even if the arrangement order of the frequency band division circuit 4 and the characteristic correction inverse filter 7 is changed, the operation remains the same.

Example 2. FIG. 2 is a block diagram showing an embodiment in which the digital channel divider according to the present invention is applied not only to a multi-amp speaker system but also to other general audio systems. In the figure, symbols 6, _{6 1} , 6 ₂ , . . . , 6 _n are audio systems connected to the channel divider 10, which are generally represented here by particularly expressing transmission characteristics. Other symbols are the same as or correspond to those in FIG. 1, and their explanation will be omitted.

The operation in FIG. 2 is basically the same as in FIG. 1. However, since the audio system 6 is generally connected to the D/A conversion circuits 5, ₅₁ , ₅₂ ,... _5n , the inverse filter coefficient generation circuits ₇₁₁ , ₇₂₂ ,... _7nn are As the coefficient data, data giving the inverse characteristic of the overall transmission characteristic excluding the characteristic correction inverse filter 7 until the digital input signal finally completes the operation of the audio system 6 is provided. At this time, the characteristics finally obtained are that the transmission characteristics of the audio system 6 and the characteristics of the characteristic correction inverse filter 7 cancel each other out, resulting in a flat amplitude and a linear phase, realizing faithful transmission and reproduction of the acoustic signal. .

[0016] The digital channel divider of this invention is compatible with the above audio system. In addition to applications, equipment that separates and processes frequency bands in digital signal systems, and Of course, the present invention can be widely applied to devices that extract a desired frequency band.

[0017]

[Effect of the idea] As described above, according to the digital channel divider of the present invention, each channel Simultaneously flatten the amplitude characteristics and linearize the phase frequency characteristics of the overall transmission frequency characteristics of This has the effect of transmitting and reproducing acoustic signals without distortion.

[0018]

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional example of a multi-amplifier speaker system using a digital channel divider.

[Explanation of symbols]

2 _, 2 1 , _{2 2} , ... 2 _n Power amplifier 3, _{3 1} , 3 ₂ , ... 3 _n Speaker unit 4 Frequency band division circuit 4 ₁ , 4 ₂ , ... 4 _n Linear phase FIR type filter 4 ₁₁ , 4 ₂₂ ,...4 _nn Filter coefficient variable device 5, _{5 1} , 5 ₂ ,... 5 _n D/A conversion circuit 6, _{6 2} ,..., 6 _n Audio system 7 Inverse filter for characteristic correction 7 ₁ , 7 ₂ ,... 7 _i ...7 FIR filter for _n characteristic correction 7 ₁₁ , 7 ₂₂ , ...7 _ii ...7 Coefficient generation circuit for _nn inverse filter 10 Digital channel divider 20 Microphone

Claims (1)

[Scope of utility model registration request] Claim 1: A digital channel divider configured to connect a plurality of filters in parallel so that desired transmission frequency characteristics can be arbitrarily set for a digital input signal, and to output the signals output from each filter independently. There is a calculation means for calculating a time-series impulse response based on the inverse characteristics for flattening the amplitude characteristics and linearizing the phase frequency characteristics of the overall transmission frequency characteristics of each channel, and A digital channel divider comprising: a real-time processing digital filter that uses the time-series impulse response as a filter coefficient and convolves the filter coefficient with a digital input signal.