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JPH04103795

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DESCRIPTION JPH04103795
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
digital channel dividers used, for example, in audio systems.
[0002]
2. Description of the Related Art Conventionally, in a multi-way speaker system using, for
example, a combination of a plurality of dedicated speakers for the frequency band, a system
using an LC network composed of a coil and a capacitor, each frequency band A multi-amplifier
system using a dedicated channel divider for each channel is adopted. A channel divider used in
the LC network or multi-amplifier system has a function of frequency dividing an audio
frequency band into several necessary frequency bands and supplying an acoustic signal to a
speaker dedicated to the corresponding frequency band.
[0003]
By the way, in the multi-amplifier system, digitization of channel dividers composed of electronic
circuits has been advanced. FIG. 1 is an embodiment of a channel divider disclosed in Japanese
Utility Model Application Publication No. 2-6673 and is a block diagram showing an example of a
speaker system by the above-mentioned multi-amplifier system using a digital system. In the
figure, 2, 21, 22,... 2n are a plurality of power amplifiers, 3, 31, 32,... 3n are a plurality of speaker
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units, and 4 is a channel divider (frequency band division circuit). The linear phase FIR type
filters 41, 42,. , 411, 422,..., 4 nn are a plurality of filter coefficient variable devices which are
operation means for giving filter coefficients for giving the desired frequency band division
characteristics to the linear phase FIR type filter, 5, 51, 52,. .. 5n are a plurality of D / A
conversion circuits.
[0004]
In the above-described multi-way speaker system, digital signal input is applied to the channel
divider 4 and filter coefficients for providing desired frequency band division characteristics with
the linear phase FIR type filters 41, 42,. The variable devices 411, 422,... Next, the outputs of the
linear phase FIR filters 4, 41, 42,... 4n are converted into analog signals by the respective D / A
converters 5, 51, 52,. 22 2... 2 n The signal is amplified to a predetermined level and supplied to
the speaker units 3 31 32 3.
[0005]
Since the above-mentioned multi-way speaker system uses the linear phase FIR type filters 4, 41,
42, ... 4n as channel dividers, the channel dividers should be linear. Although the phase
characteristics are maintained, the sound pressure frequency characteristics of the speaker unit
generally do not exhibit a linear phase, so the finally obtained sound pressure characteristics can
not always be a linear phase. As a result, the waveform of the reproduced sound is distorted,
making it difficult to faithfully reproduce the sound.
[0006]
The present invention has been made to solve the above-mentioned problems, and at the same
time realizes flattening of the amplitude characteristic of the total transmission frequency
characteristic of each channel and linearization of the phase frequency characteristic. It is an
object of the present invention to provide a digital channel divider that enables faithful
transmission and faithful reproduction of an acoustic signal.
[0007]
SUMMARY OF THE INVENTION In the digital channel divider according to the present invention,
an inverse filter for characteristic correction which simultaneously realizes flattening of the
amplitude characteristic of the total transmission frequency characteristic of each channel and
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linearization of the phase frequency characteristic. Provide
[0008]
The digital channel divider according to the present invention can flatten the amplitude
characteristic of the total transmission frequency characteristic of each channel and linearize the
phase frequency characteristic, thereby faithfully transmitting the acoustic signal without
waveform distortion, Realize faithful reproduction.
[0009]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram showing
an embodiment in which the digital channel divider according to the present invention is used in
a multi-amplifier speaker system.
In FIG. 1, symbols 2, 21, 22,... 2n are power amplifiers, 3, 31, 32,... 3n are speaker units, 10 is a
digital channel divider according to the present invention, 4, 41, 42,. , Which is a component of
the frequency band dividing circuit 7 is a component of the digital channel divider 10, and is for
characteristic correction for realizing flattening of the amplitude characteristic of the total
transmission frequency characteristic of each channel and linearization of the phase frequency
characteristic. Inverse filters 71, 72,... 7n are FIR filters for characteristic correction which are
components of the inverse filter 7 for characteristic correction, 711, 722,... 7nn are coefficient
generating circuits for inverse filters 5, 51, 52,. Is a D / A conversion circuit for converting a
digital signal into an analog signal.
[0010]
In FIG. 1, the digital input signal is first led to the frequency band dividing circuit 4.
The frequency band division circuit 4 is divided into desired frequency bands by digital filters
such as FIR filters and IIR filters.
[0011]
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The output signal of the frequency band dividing circuit 4 is next inputted to the inverse filter 7
for characteristic correction.
In the characteristic correction inverse filter 7, the output signal from the frequency band
dividing circuit 4 and the coefficient data of the inverse filter coefficient generation circuits 711,
722,... 7nn are real time by the characteristic correction FIR filters 71, 72,. The convolution
operation is performed at.
[0012]
Here, the coefficient data of the inverse filter coefficient generation circuits 711, 722,..., 7 nn is a
comprehensive data system excluding the characteristic correction inverse filter 7 in the system
until the digital signal is input and finally reaches the microphone 20. Set as coefficient data that
gives the inverse characteristic of transmission characteristics.
[0013]
As described above, the digital signals previously corrected by the characteristic correction
inverse filter 7 are then converted into analog signals by the D / A conversion circuits 5, 51, 52,.
22,..., 2n are led to speaker units 3, 31, 32,.
In the speaker units 3, 31, 32,... 3n, the convolution operation of the corrected analog signal and
the impulse response of the speaker unit is performed, and the finally obtained characteristics
cancel each other out, and the sound pressure is flat and the phase is It becomes a straight line,
and faithful transmission and reproduction of an acoustic signal are realized. The operation is the
same even if the order of arrangement of the frequency band dividing circuit 4 and the inverse
filter for characteristic correction 7 is interchanged.
[0014]
Embodiment 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-amplifier speaker system
but also to other general audio systems. In the figure, the symbols 6, 61, 62,..., 6n are audio
systems connected to the channel divider 10 and are generally represented here by being
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represented in particular by transmission characteristics. The other symbols are the same as or
equivalent to those in FIG. 1, and the description will be omitted.
[0015]
The operation in FIG. 2 is basically the same as in FIG. However, since the audio system 6 is
generally connected to the D / A conversion circuits 5, 51, 52,... 5n, the coefficient data of the
inverse filter coefficient generation circuits 711, 722,. Data giving an inverse characteristic of the
overall transmission characteristic excluding the inverse filter 7 for characteristic correction until
the input signal finally completes the operation of the audio system 6 is given. At this time, the
characteristic finally obtained is that the transmission characteristic of the audio system 6 and
the characteristic of the inverse filter 7 for characteristic correction mutually cancel each other,
and the amplitude becomes flat and a phase straight line, realizing faithful transmission and
reproduction of the acoustic signal. .
[0016]
The digital channel divider of the present invention can be widely applied not only to the
application to the above audio system but also to an apparatus for dividing and processing a
frequency band in a digital signal system and an apparatus for extracting a desired frequency
band. is there.
[0017]
As described above, according to the digital channel divider of the present invention, the
flattening of the amplitude characteristic of the total transmission frequency characteristic of
each channel and the linearization of the phase frequency characteristic are simultaneously
realized. It has the effect of transmitting and reproducing without distortion.
[0018]
【0018】
[0019]
Brief description of the drawings
[0020]
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1 is a block diagram showing a first embodiment of the present invention.
[0021]
2 is a block diagram showing a second embodiment of the present invention.
[0022]
FIG. 3 is a block diagram showing a conventional example of a multi-amplifier speaker system
using a digital channel divider.
[0023]
Explanation of sign
[0024]
2, 21, 22,..., 2 n power amplifier 3, 31, 32, 32,... 3 n speaker unit 4 frequency band dividing
circuit 41, 42,... 4 n linear phase FIR type filter 411, 422,. 52, ... 5n D / A conversion circuit 6, 62,
..., 6n Audio system 7 Inverse filter 71 for characteristic correction 71, 72, ... 7i ... 7n FIR filter for
characteristic correction 711, 722, ... 7ii ... 7nn Coefficient generation for inverse filter Circuit 10
Digital Channel Divider 20 Microphone
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