JPH026673Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates primarily to a channel divider used in digital audio equipment.

BACKGROUND ART Conventionally, for example, in a stereo device of a multi-way speaker system (dividing the audible band into several parts and reproducing them with dedicated speakers),
The LC network method or multiple channel amplifier method (hereinafter referred to as the multi-amplifier method) is adopted.

The multi-amplifier method uses a channel divider that includes a plurality of filters for dividing the audible band into several necessary bands (a plurality of frequency bands corresponding to the speaker system).

FIG. 1 is a block diagram showing an example of the configuration of essential parts of the multi-amplifier type audio device. In the figure, 1 is a channel divider that consists of a plurality of filters 1 each having different amplitude and frequency characteristics.
₁ , 1 ₂ , ...1 _o . 2, _{2 1} , 2 ₂ ,…
...2 _o is a plurality of power amplifiers, and 3 is a multiway speaker including a plurality of speakers 3 ₁ , 3 ₂ , . . . 3 _o .

When an analog input signal is input to the channel divider 1, it is divided into frequency bands corresponding to each of the multiway speakers 3 (for example, super tweeter, tweeter, squawker, woofer, super woofer, etc.), and this filtered signal is is output. This output is amplified by independent power amplifiers 2 _{, 2 1} , 2 ₂ , . . . 2 _o , respectively, and drives dedicated speakers 3 _{, 3 1} , 3 ₂ , .

In the above conventional configuration, each filter 1 ₁ , 1 ₂ , . . . 1 _o constituting the channel divider 1
Because they use analog filters, they each cause phase rotation, causing problems such as mislocalization of the sound and loss of clarity of the sound, making it difficult to reproduce the sound faithfully.

DISCLOSURE OF THE INVENTION An object of the present invention is to solve the problems in the prior art described above and to provide a channel divider that does not cause phase rotation in the filter.

In order to achieve the above object, the digital channel divider of the present invention calculates a time-series impulse response, which is a filter coefficient, based on a desired amplitude-frequency characteristic in which the phase-frequency characteristic is linear, that is, the phase-frequency characteristic does not change. A linear phase transversal filter (linear phase FIR) is a real-time processing digital filter equipped with calculation means.
It is constructed by arranging multiple filters in parallel.

The calculation means performs a discrete inverse Fourier transform to calculate a time-series impulse response. This time series impulse response is the above linear phase FIR
Provided to the filter as filter coefficients.

Also, when the phase frequency characteristic is a straight line (linear phase),
This means that in a filter having an impulse response that provides an arbitrary amplitude frequency characteristic that satisfies this condition, the phase frequency characteristic does not change. This can be seen on pages 158 to 160 and pages 235 to 237 of ``Digital Signal Processing (Part 1)'' translated by Gen Date, published by Coronasha Publishing.
It has already been mentioned on page etc.

With this configuration, the digital channel divider of the present invention can completely eliminate phase rotation.
When this is used, for example, as a channel divider in a multi-amp digital audio device, faithful reproduction of sound can be easily realized.

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of main parts when the digital channel divider of the present invention is used in a multi-amplifier type digital audio device. In the figures, the same reference numerals as those described above indicate the same or equivalent parts. 4 is a digital channel divider of the present invention;
₁ , 4 ₂ , ... 4 _o are linear phase transversal filters (linear phase FIR filters), 4 ₁₁ , 4 ₂₂ , ...
...4 _oo is a calculation means, which is composed of a console and a calculation circuit (not shown), into which the user inputs amplitude data (amplitude frequency characteristics) at the frequency point to be controlled from the console. , supplies this data to the arithmetic circuit. The arithmetic circuit performs a discrete inverse Fourier transform to calculate a time-series impulse response. This time-series impulse response is generated by the linear phase FIR filters 4 ₁ , 4 ₂ ,...
…4 Desired frequency characteristics (frequency band) for each _o
It is supplied as a filter coefficient to have . 5, 5 ₁ , 5 ₂ , ... 5 _o is a D/A converter,
This is for converting the digital signals filtered and divided into a plurality of bands by the digital channel divider 4 into analog signals, respectively.

The above linear phase FIR filter 4 ₁ , 4 ₂ ,...4 _o
is a digital signal input and the calculation means 4 ₁₁ ,
The filter coefficients given by 4 _{22 ,} .

Next, the operation and usage of an audio device using the digital channel divider of the present invention will be explained.

A digital signal input is _applied to a plurality of linear phase _FIR filters _{4 1} , 4 ₂ , . _D /A conversion is performed at the power amplifier _{2 1 , 2 2} , _. It is what drives the. and each linear phase FIR
The amplitude frequency characteristics of filters 4 ₁ , 4 ₂ , ... 4 _o are as follows:
The calculation means 4 ₁₁ , 4 ₂₂ , ... 4 _oo calculates the amplitude at the frequency point that the user wants to control from the operation console ( _not shown) according to the frequency band of the driven speakers 3 ₁ , 3 ₂ , ... 3 o. It can be changed arbitrarily by inputting data.

As explained above, the digital channel divider of the present invention is constructed using a linear phase transversal filter that does not cause phase rotation and can produce a predetermined amplitude frequency characteristic. When used in an amplifier type digital audio device, it is possible to connect various speakers with different amplitude and frequency characteristics, and faithful reproduction of sound can be realized.

In addition to the above-mentioned application of the digital channel divider of the present invention to the audio equipment,
It goes without saying that the present invention can be widely applied to devices that divide and process frequency bands in digital signal systems, and devices that extract desired frequency bands.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the main part configuration of a conventional multi-amplifier type audio device, and Fig. 2 is a block diagram showing the main part structure when the digital channel divider of the present invention is used in a multi-amplifier type digital audio device. It is. 1... Channel divider, 2, 2 ₁ , 2 ₂ ,
...2 _o ... power amplifier, 3, 3 ₁ , 3 ₂ , ...
3 _o ... multiway speaker, 4 ... digital channel divider, 4 ₁ , 4 ₂ , ... 4 _o ...
...Real-time processing digital filter (linear phase transversal filter), 4 ₁₁ , 4 ₂₂ , ... 4 _oo ...
...Arithmetic means (filter coefficient variable device), 5, 5 ₁ ,
5 ₂ ,...5 _o ...D/A converter.

Claims (1)

[Claims for Utility Model Registration] A digital channel in which a plurality of filters that can arbitrarily set desired amplitude-frequency characteristics for digital input signals are connected in parallel, and the signals output from each filter are output independently. The divider is a calculation means for calculating a time series impulse response based on a desired amplitude frequency characteristic in which the phase frequency characteristic does not change, and the time series impulse response outputted by the calculation means is used as a filter coefficient, and the filter A digital channel divider comprising a real-time processing digital filter that convolves coefficients and a digital input signal.