close

Вход

Забыли?

вход по аккаунту

?

JP2015015618

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2015015618
An audio system and an audio signal transmission method capable of obtaining high sound
quality with low power consumption without increasing cost. SOLUTION: While applying a power
supply voltage to a single transmission path, an audio reproduction unit 11 converts it into a
digital reproduction audio data signal AD and supplies it to a transmission signal processing unit
13. The volume operation unit 12 separately receives the volume adjustment operation of the
speaker 4a and the volume adjustment operation on the speaker 4b, and supplies volume
adjustment data VOLa and VOLb indicating the volume adjustment amount to the transmission
signal processing unit. The volume operation unit supplies, to the transmission signal processing
unit 13, volume adjustment data VOLa indicating the volume adjustment amount for the speaker
4a and volume adjustment data VOLb indicating the volume adjustment amount for the speaker
4b. [Selected figure] Figure 1
Audio system and method of transmitting audio signal
[0001]
The present invention relates to an audio system and an audio signal transmission method for
transmitting an audio signal to a speaker via a transmission path.
[0002]
In an on-vehicle audio system, since power is supplied from a battery of a car, reduction in power
consumption is desired.
09-05-2019
1
On the other hand, in order to achieve high sound quality, an on-vehicle audio system equipped
with a large-output class A or class B power amplifier with large power consumption as a power
amplifier for driving a speaker has been commercialized. Therefore, in order to achieve both low
power consumption and high sound quality, an audio system has been proposed that uses a
digital amplifier capable of obtaining high output with low power consumption, a so-called class
D amplifier, as this power amplifier. (See, for example, FIG. 8 of Patent Document 1). In such an
audio system, a class D power amplifier is provided on the speaker side, and an audio signal is
supplied to the class D power amplifier through a transmission path.
[0003]
When a class D power amplifier is provided on the speaker side, a power cable for supplying
power to the class D power amplifier is required. As a result, the scale of the entire system has
become large, resulting in an increase in cost.
[0004]
Moreover, in such an acoustic system, since the amplitude of the audio signal is small when the
volume is small, there is a problem that the sound quality deterioration due to the loss in the
transmission path becomes remarkable.
[0005]
JP, 2006-267534, A
[0006]
An object of the present invention is to provide an audio system and an audio signal transmission
method capable of obtaining high sound quality with low power consumption without increasing
cost.
[0007]
An audio system according to the present invention generates a transmission signal processing
unit for transmitting a modulated audio signal obtained by modulating an audio signal and a
control data signal including information indicating volume adjustment amount to a single
transmission path, and a power supply voltage. An audio signal transmission unit including a
power supply voltage generation unit for applying the same to the transmission path; and a
09-05-2019
2
reception signal processing unit for demodulating the audio signal and the control data signal
from the modulated audio signal received via the transmission path An amplifier for supplying an
amplified audio signal obtained by amplifying the audio signal with a gain corresponding to the
volume adjustment amount indicated by the control data signal to a speaker; and taking out the
power supply voltage from the transmission path; And a reception amplification unit including a
power supply voltage deriving unit to be supplied to the reception signal processing unit.
[0008]
Further, a method of transmitting an audio signal according to the present invention is a method
of transmitting an audio signal of an audio system, which transmits an audio signal and supplies
an amplified audio signal obtained by amplifying the received audio signal by an amplifier to a
speaker. A modulated audio signal obtained by modulating the audio signal and a control data
signal including information indicating the volume adjustment amount is sent to the transmission
path while applying a voltage to a single transmission path, and is taken out from the
transmission path. It demodulates the audio signal and the control data signal from the
modulated audio signal received through the transmission path while supplying the power
supply voltage to the amplifier, and corresponds to the volume adjustment amount indicated by
the control data signal. The amplifier is controlled to amplify the audio signal with a fixed gain.
[0009]
FIG. 1 is a block diagram showing an audio system according to the present invention.
FIG. 6 is a block diagram showing an example of an internal configuration of a transmission
signal processing unit 13.
FIG. 5 is a frequency characteristic diagram showing reproduction frequency bands of the
speakers 4a and 4b.
It is a time chart which shows an example of operation in the audio system concerning the
present invention.
It is a block diagram which shows an example of an internal structure of receiving signal
processing part 32a and 32b.
09-05-2019
3
FIG. 16 is a block diagram showing another example of the internal configuration of the
transmission signal processing unit 13. It is a block diagram which shows an example of an
internal structure of receiving signal processing part 32a and 32b. It is a time chart which shows
another example of operation in the audio system concerning the present invention. It is a block
diagram which shows another example of the audio system which concerns on this invention. It
is a block diagram which shows the internal structure of the transmission output control part
35a and the received signal processing part 320b. It is a time chart which shows the
transmission timing of the audio signal transmission part 1, and the transmission output control
parts 35a and 35b. FIG. 3 is a block diagram showing an internal configuration of a transmission
signal processing unit 130 and a transmission output control unit 16; It is a block diagram
showing a schematic structure of an audio system including a speaker system for right and left 2
channels. It is a time chart which shows an example of operation | movement in the audio system
shown in FIG.
[0010]
FIG. 1 is a block diagram showing the configuration of an audio system according to the present
invention.
[0011]
The audio system shown in FIG. 1 includes an audio signal transmission unit 1, a transmission
cable 2, reception amplification units 3a and 3b, and speakers 4a and 4b.
[0012]
The audio signal transmission unit 1 includes an audio reproduction unit 11, a volume control
unit 12, a transmission signal processing unit 13, a capacitor 14, and a power supply voltage
generation unit 15.
[0013]
The audio reproduction unit 11 is, for example, a music player (not shown) that reproduces an
audio signal from a storage medium such as a magnetic disk, an optical disk, or a semiconductor
memory, or a reproduction supplied via a communication network such as broadcast waves or
the Internet. It includes a radio receiver or an information reproduction device (not shown) for
acquiring an audio signal.
09-05-2019
4
The audio reproduction unit 11 converts an audio signal reproduced from the storage medium or
the communication network as described above into a digital reproduction audio data signal AD
having a format according to, for example, I2S (Inter-IC Sound) standard, and transmits this The
signal processing unit 13 is supplied.
[0014]
The volume operation unit 12 individually receives the volume adjustment operation by the user,
that is, the volume adjustment operation for the speaker 4a and the volume adjustment operation
for the speaker 4b, respectively, and transmits volume adjustment data VOLa and VOLb
indicating the volume adjustment amount to the transmission signal processing unit 13 Supply to
That is, the volume operation unit 12 supplies the transmission signal processing unit 13 with
volume adjustment data VOLa indicating the volume adjustment amount for the speaker 4 a and
volume adjustment data VOLb indicating the volume adjustment amount for the speaker 4 b.
[0015]
FIG. 2 is a block diagram showing an internal configuration of the transmission signal processing
unit 13.
[0016]
As shown in FIG. 2, the transmission signal processing unit 13 includes filters 131 and 132, error
correction coding circuits 133 and 134, a frame generation circuit 135, a modulation circuit 136,
a DA converter 137, and a transmission amplifier 138.
[0017]
The filter 131 is a digital band pass filter made of, for example, an FIR (Finite Impulse Response)
filter.
09-05-2019
5
The filter 131 is obtained by filtering the above-mentioned reproduced audio data signal AD with
a band pass characteristic to transmit only the component of the frequency band equal to the
reproduced frequency band fa of the speaker 4a as shown in FIG. The audio data signal FDa is
supplied to the error correction coding circuit 133.
Incidentally, as shown in FIG. 3, the reproduction frequency band fa is a frequency band on the
bass side when the audio frequency band is divided into two parts, the high band side and the
low band side.
Therefore, the filter 131 functions as a dividing network on the low frequency band side.
However, as described above, not the low pass filter but the band pass filter is used as the filter
131.
[0018]
The error correction coding circuit 133 supplies an audio data signal CDa obtained by
performing an error correction coding process such as a BCH code or a Reed-Solomon code to
the audio data signal FDa to a frame generation circuit 135.
[0019]
The filter 132 is a digital band pass filter made of, for example, an FIR filter.
The filter 132 is obtained by filtering the above-mentioned reproduced audio data signal AD with
a band pass characteristic to transmit only the component of the frequency band equal to the
reproduced frequency band fb of the speaker 4b as shown in FIG. The audio data signal FDb is
supplied to the error correction coding circuit 134. As shown in FIG. 3, the reproduction
frequency band fb is a frequency band on the high sound side when the audio frequency band is
divided into two parts, the high sound side and the low sound side. Thus, the filter 132 functions
as a high band side dividing network. However, as described above, not the high pass filter but
the band pass filter is used as the filter 132.
[0020]
The error correction coding circuit 134 supplies an audio data signal CDb obtained by
performing an error correction coding process such as a BCH code or a Reed-Solomon code to
09-05-2019
6
the audio data signal FDb to a frame generation circuit 135.
[0021]
The frame generation circuit 135 arranges the audio data signals CDa and CDb in time division
for each frame of a predetermined length as shown in FIG. 4, and together with CDa and CDb in
each frame, volume adjustment data VOLa and VOLb, and phase adjustment A frame audio signal
FA formed by arranging data PCa and PCb in order is generated.
That is, the frame generation circuit 135 generates a frame audio signal FA obtained by time
division multiplexing audio data signals (CDa, CDb) and control data signals including volume
adjustment data VOLa and VOLb and phase adjustment data PCa and PCb. It is to do. The phase
adjustment data PCa (PCb) is an adjustment value for adjusting the phase of an audio signal
(described later) supplied to the speaker 4a (4b), that is, the phase of sound output from the
speakers 4a and 4b. It is information indicating a phase adjustment value for making the position
match. The frame generation circuit 135 supplies the above-described frame audio signal FA to
the modulation circuit 136.
[0022]
The modulation circuit 136 performs DA modulation on a modulated audio data signal MD
obtained by performing digital modulation such as QPSK (Quadrature phase shift keying)
modulation or QAM (Quadrature amplitude modulation) on the frame audio signal FA described
above. Supply to 137. The DA converter 137 converts the modulated audio data signal MD into a
modulated audio signal MA of an analog signal, and supplies this to the transmission amplifier
138.
[0023]
The transmission amplifier 138 transmits the modulated audio signal TX obtained by amplifying
the modulated audio signal MA to the reception amplifiers 3 a and 3 b via the capacitor 14 and
the transmission cable 2. The transmission cable 2 is composed of one signal line for
transmitting the above-mentioned modulated audio signal TX and one ground line, for example, a
single transmission such as a coaxial cable, a twisted pair line, or a parallel line. It is a road. One
09-05-2019
7
end of the capacitor 14 is connected to the output end of the transmission signal processing unit
13, and the other end is connected to the signal line of the transmission cable 2. The capacitor
14 blocks the direct current component on the signal line from flowing into the transmission
signal processing unit 13.
[0024]
The power supply voltage generation unit 15 generates a DC power supply voltage VDD for
driving the reception amplification units 3 a and 3 b, and applies the generated power supply
voltage VDD to the signal line of the transmission cable 2.
[0025]
With the above configuration, the audio signal transmission unit 1 generates a frame audio signal
FA obtained by time-division multiplexing the audio data signals (CDa, CDb) and the control data
signals (VOLa, VOLb, PCa, PCb), and modulates the frame audio signal FA. The applied modulated
audio signal TX is supplied to the reception amplification units 3a and 3b via the transmission
cable 2 together with the DC power supply voltage VDD.
[0026]
The reception amplification unit 3a includes a capacitor 31a, a reception signal processing unit
32a, a class D amplifier 33a, and a power supply voltage derivation unit 34a.
One end of the capacitor 31a is connected to the signal line in the transmission cable 2, and the
other end is connected to the input end of the reception signal processing unit 32a.
The capacitor 31a blocks the direct current component on the signal line of the transmission
cable 2 from flowing into the input end of the reception signal processing unit 32a. The
modulated audio signal TX transmitted from the audio signal transmission unit 1 is supplied to
the reception signal processing unit 32a as a reception modulated audio signal RXa via the
transmission cable 2 and the capacitor 31a.
[0027]
FIG. 5 is a block diagram showing an internal configuration of the reception signal processing
units 32a and 32b.
09-05-2019
8
[0028]
As shown in FIG. 5, the reception signal processing unit 32a includes a reception amplifier 321a,
an AD converter 322a, a demodulation circuit 323a, a data extraction circuit 324a, an error
correction circuit 325a, a control signal generation circuit 326a, and a variable delay circuit
327a.
The reception amplifier 321a supplies a modulated audio signal RAa obtained by amplifying the
reception modulated audio signal RXa to the AD converter 322a. The AD converter 322a
converts the modulated audio signal RAa into a modulated audio data signal RDa in digital form
and supplies it to the demodulation circuit 323a. The demodulation circuit 323a subjects the
modulated audio data signal RDa to demodulation processing corresponding to digital
modulation in the modulation circuit 136 of the transmission signal processing unit 13 described
above, to obtain frame audio having a data format as shown in FIG. The signal FA is restored and
supplied to the data extraction circuit 324a as a frame audio signal FRa.
[0029]
The data extraction circuit 324a extracts the audio data signal CDa, the volume adjustment data
VOLa, and the phase adjustment data PCa from each frame in the frame audio signal FRa. Then,
the data extraction circuit 324a supplies the audio data signal CDa to the error correction circuit
325a, and supplies the volume adjustment data VOLa and the phase adjustment data PCa to the
control signal generation circuit 326a. The error correction circuit 325a performs error
correction processing on the audio data signal CDa to generate an audio data signal QDa in which
error bits are corrected, and supplies the audio data signal QDa to the variable delay circuit 327a.
The control signal generation circuit 326a generates a gain adjustment signal VLa whose gain
should be adjusted by the adjustment amount of the volume indicated by the volume adjustment
data VOLa, and supplies this to the class D amplifier 33a. Furthermore, as shown in FIG. 4, the
control signal generation circuit 326a performs phase adjustment indicated by the phase
adjustment data PCa at an offset delay time Tof1 for absorbing the time difference between the
audio data signals CDa and CDb in each frame. The delay control signal DLa indicating the delay
time obtained by adding the values is supplied to the variable delay circuit 327a. The offset delay
time Tof1 is a delay time with respect to the audio data signal CDa, which is set to eliminate the
time difference between the leading portions of the audio data signals CDa and CDb separated by
time division multiplexing. The variable delay circuit 327a delays the audio data signal QDa by
09-05-2019
9
the delay time indicated by the delay control signal DLa as an audio data signal AGa, and supplies
this to the class D amplifier 33a.
[0030]
The class D amplifier 33a is a class D power amplifier, which amplifies the audio data signal AGa
with the gain indicated by the above-mentioned gain adjustment signal VLa to generate an
amplified audio signal AVa for driving the speaker 4a. It supplies to the speaker 4a. The power
supply voltage deriving unit 34a derives the DC power supply voltage VDD superimposed on the
signal line of the transmission cable 2, and operates the received signal processing unit 32a and
the class D amplifier 33a described above. Supply to each as a power source.
[0031]
The speaker 4a is a so-called woofer that uses the reproduction frequency band fa shown in FIG.
3, that is, the low frequency band side when the audio frequency band is divided into two parts in
the high band side and the low band side, as the reproduction frequency band. Sound output
according to the signal AVa is performed. At this time, the amplified audio signal AVa is obtained
by band-limiting the frequency band of the reproduced audio data signal AD sent from the audio
reproducing unit 11 to the above-described reproduced frequency band fa. Therefore, the
speaker 4a as a woofer performs sound output in the low frequency range according to the
amplified audio signal AVa.
[0032]
In FIG. 1, the reception amplification unit 3b includes a capacitor 31b, a reception signal
processing unit 32b, a class D amplifier 33b, and a power supply voltage derivation unit 34b.
One end of the capacitor 31b is connected to the signal line of the transmission cable 2, and the
other end is connected to the input end of the reception signal processing unit 32b. The
capacitor 31 b blocks the direct current component on the signal line of the transmission cable 2
from flowing into the input end of the reception signal processing unit 32 b. The modulated
audio signal TX transmitted from the audio signal transmission unit 1 is supplied to the reception
signal processing unit 32b as a reception modulated audio signal RXb via the transmission cable
2 and the capacitor 31b.
09-05-2019
10
[0033]
As shown in FIG. 5, the reception signal processing unit 32b includes a reception amplifier 321b,
an AD converter 322b, a demodulation circuit 323b, a data extraction circuit 324b, an error
correction circuit 325b, a control signal generation circuit 326b, and a variable delay circuit
327b. The reception amplifier 321b supplies a modulated audio signal RAb obtained by
amplifying the reception modulated audio signal RXb to the AD converter 322b. The AD
converter 322 b converts the modulated audio signal RAb into a modulated audio data signal
RDb in digital form, and supplies it to the demodulation circuit 323 b. The demodulation circuit
323b subjects the modulated audio data signal RDb to demodulation processing corresponding
to digital modulation in the modulation circuit 136 described above to restore a frame audio
signal FA having a data format as shown in FIG. This is supplied to the data extraction circuit
324b as a frame audio signal FRb.
[0034]
The data extraction circuit 324b extracts the audio data signal CDb, the volume adjustment data
VOLb, and the phase adjustment data PCb from each frame in the frame audio signal FRb. Then,
the data extraction circuit 324b supplies the audio data signal CDb to the error correction circuit
325b, and supplies the volume adjustment data VOLb and the phase adjustment data PCb to the
control signal generation circuit 326b. The error correction circuit 325 b performs error
correction processing on the audio data signal CDb to generate an audio data signal QDb in
which error bits are corrected, and supplies the audio data signal QDb to the variable delay
circuit 327 b. The control signal generation circuit 326b generates a gain adjustment signal VLb
whose gain should be adjusted by the adjustment amount of the volume indicated by the volume
adjustment data VOLb, and supplies this to the class D amplifier 33b. Furthermore, as shown in
FIG. 4, the control signal generation circuit 326b performs phase adjustment indicated by the
phase adjustment data PCb at an offset delay time Tof2 for absorbing the time difference
between the audio data signals CDa and CDb in each frame. A delay control signal DLb indicating
a delay time obtained by adding values is supplied to the variable delay circuit 327b. The offset
delay time Tof2 is a delay time for the audio data signal CDb, which is set to eliminate the time
difference between the leading portions of the audio data signals CDa and CDb separated by time
division multiplexing. The variable delay circuit 327b delays the audio data signal QDb by the
delay time indicated by the delay control signal DLb to generate an audio data signal AGb, and
supplies this to the class D amplifier 33b.
09-05-2019
11
[0035]
The class D amplifier 33b is a class D power amplifier, which amplifies the audio data signal AGb
with the gain indicated by the above-mentioned gain adjustment signal VLb to generate an
amplified audio signal AVb for driving the speaker 4b, It supplies to the speaker 4b. The power
supply voltage deriving unit 34b derives the DC power supply voltage VDD superimposed on the
signal line of the transmission cable 2, and operates the received signal processing unit 32b and
the class D amplifier 33b described above. Supply to each as a power source.
[0036]
The speaker 4b is a so-called tweeter whose reproduction frequency band is the reproduction
frequency band fb shown in FIG. 3, that is, the high band side when the audio frequency band is
divided into two parts to the high band side and the low band side. Sound output according to the
signal AVb is performed. At this time, the amplified audio signal AVb is obtained by band-limiting
the frequency band of the reproduced audio data signal AD sent from the audio reproducing unit
11 to the above-described reproduced frequency band fb. Therefore, the speaker 4b as a tweeter
performs acoustic output of a high range according to the amplified audio signal AVa.
[0037]
As described above, in the audio system, the audio signal transmission unit (1) transmits an audio
signal as described below while applying a DC power supply voltage (VDD) to a single
transmission path (2). That is, modulation is performed on a control data signal including an
audio signal (FDa, CDa, FDb, CDb), information (VOLa, VOLb) indicating volume adjustment
amount, and information (PCa, PCb) indicating phase adjustment value The audio signal (TX) is
transmitted to the reception amplifier (3a, 3b) via the transmission path. At this time, the
reception amplification unit takes out the power supply voltage from the transmission line and
operates by the supply of the power supply voltage, and performs the following reception
processing. That is, the reception amplification unit demodulates the above-described audio
signal and control data signal from the received modulated audio signal, and delays the audio
signal for a time based on the phase adjustment value indicated by the control data signal. The
audio signal subjected to the phase adjustment is supplied to a class D amplifier (33a, 33b) as a
power amplifier. At this time, the class D amplifier is an amplified audio signal (AVa, AVb)
obtained by amplifying the amplitude of the audio signal with a gain (VLa, VLb) according to the
volume adjustment amount indicated by the control data signal. To the speakers (4a, 4b).
09-05-2019
12
Therefore, the speaker performs acoustic output based on the audio signal at a volume according
to the volume adjustment amount indicated by the control data signal transmitted from the audio
signal transmission unit.
[0038]
According to the audio system, according to the volume adjustment operation performed on the
audio signal transmission unit 1 side, the volume adjustment by gain adjustment of the class D
amplifier provided on the speaker side is performed. As a result, even if adjustment to be set to a
small volume is performed by the volume adjustment operation, the amplitude of the audio signal
itself flowing through the transmission path is not reduced, so that the sound quality
deterioration due to the transmission path loss at the small volume is suppressed It is possible to
[0039]
Further, in this audio system, in accordance with the volume adjustment operation performed in
the audio signal transmission unit 1, the volume adjustment for the class D amplifier (33a) on the
woofer side and the class D amplifier (33b) on the tweeter side are individually performed. Can.
Therefore, it becomes possible to provide a good sound output in which the sound pressure of
each band is constant at the listening position.
[0040]
Further, in this audio system, the audio device side supplies a DC power supply voltage for
operating the class D amplifier together with the modulated audio signal to the reception
amplifier side through a single transmission path. Therefore, a dedicated power supply cable for
supplying the power supply voltage is not required, and the cost increase can be suppressed.
[0041]
Furthermore, in the above audio system, when the audio signal is supplied to the class D
amplifier, the filter (131, 132) transmits only the frequency band equal to the reproduction
frequency band (fa, fb) of the speaker connected to the class D amplifier. The audio data signals
09-05-2019
13
(FDa, FDb, CDa, CDb) are supplied to the class D amplifier. Thus, even if the audio signal (AD)
serving as the source includes a component of a frequency band that can not be reproduced by
the speaker, the class D amplifier is an audio signal component included in the frequency band
that can not be reproduced. Since the amplification process is not performed, the power
consumption can be reduced accordingly.
[0042]
In the above embodiment, the reproduction audio data signal AD is subjected to band division
corresponding to the reproduction frequency bands of the speakers 4a and 4b by the filters 131
and 132 provided on the audio signal transmission unit 1 side. However, the function of the filter
131 may be provided in the reception amplification unit 3a, and the function of the filter 132
may be provided in the reception amplification unit 3b. At this time, the frequency characteristics
of each of the filters may be individually controlled from the audio signal transmission unit 1
side.
[0043]
FIGS. 6 and 7 are block diagrams showing another example of the internal configuration of each
of the transmission signal processing unit 13 and the reception signal processing units 32a and
32b made in view of the above point.
[0044]
In the configuration shown in FIG. 6, the transmission signal processing unit 13 includes a
modulation circuit 136, a DA converter 137, a transmission amplifier 138, an error correction
coding circuit 139, and a frame generation circuit 140.
The error correction coding circuit 139 applies an error correction coding process such as BCH
code or Reed-Solomon code to the reproduced audio data signal AD supplied from the audio
reproduction unit 11, for example. , And the frame generation circuit 140.
[0045]
09-05-2019
14
The frame generation circuit 140 arranges the audio data signal CDD in time division for each
frame of a predetermined length as shown in FIG. 8, and together with the CDD in each frame,
volume adjustment data VOLa, VOLb, phase adjustment data PCa, PCb And generates a frame
audio signal FA in which the reproduction band setting data FCa and FCb are arranged in order.
More specifically, frame generation circuit 140 time-divisionally multiplexes audio data signal
CDD with a control data signal including volume adjustment data VOLaVOLb, phase adjustment
data PCa, PCb, reproduction band setting data FCa and FCb, and a frame audio signal FA. Is
generated. The reproduction band setting data FCa (FCb) is information for specifying the band
pass characteristic of a variable filter (described later) provided in the reception amplification
unit 3a (3b). The frame generation circuit 140 supplies the above-described frame audio signal
FA to the modulation circuit 136. The modulation circuit 136 supplies a modulated audio data
signal MD obtained by performing digital modulation such as QPSK modulation or QAM on the
frame audio signal FA described above to a DA converter 137. The DA converter 137 converts
the modulated audio data signal MD into a modulated audio signal MA of an analog signal, and
supplies this to the transmission amplifier 138. The transmission amplifier 138 transmits the
modulated audio signal TX obtained by amplifying the modulated audio signal MA to the
reception amplifiers 3 a and 3 b via the capacitor 14 and the transmission cable 2.
[0046]
As shown in FIG. 7, the reception signal processing unit 32a of the reception amplification unit
3a includes a reception amplifier 321a, an AD converter 322a, a demodulation circuit 323a, a
data extraction circuit 334a, an error correction circuit 335a, a control signal generation circuit
336a, and a variable filter. 337a and a variable delay circuit 338a. The reception amplifier 321a
supplies a modulated audio signal RAa obtained by amplifying the reception modulated audio
signal RXa received via the capacitor 31a to the AD converter 322a. The AD converter 322a
converts the modulated audio signal RAa into a modulated audio data signal RDa in digital form
and supplies it to the demodulation circuit 323a. The demodulation circuit 323a subjects the
modulated audio data signal RDa to demodulation processing corresponding to digital
modulation in the modulation circuit 136 of the transmission signal processing unit 13 described
above, to obtain frame audio having a data format as shown in FIG. The signal is restored and
supplied to the data extraction circuit 334a as a frame audio signal FRa.
[0047]
The data extraction circuit 334a extracts the audio data signal CDD, the volume adjustment data
VOLa, the phase adjustment data PCa and the reproduction band setting data FCa from each
09-05-2019
15
frame in the frame audio signal FRa as shown in FIG. Then, the data extraction circuit 334a
supplies the audio data signal CDD to the error correction circuit 335a, and supplies the volume
adjustment data VOLa, the phase adjustment data PCa and the reproduction band setting data
FCa to the control signal generation circuit 336a. The error correction circuit 335a performs
error correction processing on the audio data signal CDD to generate the corrected audio data
signal VDa of error bits, and supplies the audio data signal VDa to the variable filter 337a.
[0048]
The control signal generation circuit 336a should set the band pass characteristic of the variable
filter 337a to the band pass characteristic specified by the reproduction band setting data FCa,
for example, the band pass characteristic transmitting only the reproduction frequency band fa
of FIG. The filter coefficient Ka is supplied to this variable filter 337a. Further, the control signal
generation circuit 336a generates a gain adjustment signal VLa whose gain should be adjusted
by the adjustment amount of the volume indicated by the volume adjustment data VOLa, and
supplies this to the class D amplifier 33a. Further, the control signal generation circuit 336a
indicates the phase adjustment data PCa as an offset delay time Tof1 for absorbing a time
difference between output channels (for example, right channel and left channel) in the audio
data signal CDD in each frame. A delay control signal DLa indicating a delay time obtained by
adding the desired phase adjustment value is supplied to the variable delay circuit 338a.
[0049]
The variable filter 337a is, for example, a digital band pass filter including an FIR filter or the
like. The variable filter 337a applies, to the variable delay circuit 338a, the audio data signal QDa
obtained by filtering the audio data signal VDa supplied from the error correction circuit 335a
with the band bus characteristic according to the filter coefficient Ka described above. Supply.
That is, according to the filter coefficient Ka, the variable filter 337a transmits only the low
frequency components included in the reproduction frequency band fa of FIG. 3 out of the audio
data signal VDa, and sets this as the audio data signal QDa. It supplies the circuit 338a. The
variable delay circuit 338a delays the audio data signal QDa by the delay time indicated by the
delay control signal DLa as an audio data signal AGa, and supplies this to the class D amplifier
33a.
[0050]
09-05-2019
16
On the other hand, as shown in FIG. 7, the reception signal processing unit 32b of the reception
amplification unit 3b includes a reception amplifier 321b, an AD converter 322b, a demodulation
circuit 323b, a data extraction circuit 334b, an error correction circuit 335b, and a control signal
generation circuit 336b. A variable filter 337 b and a variable delay circuit 338 b are included.
The reception amplifier 321b supplies a modulated audio signal RAb obtained by amplifying the
reception modulated audio signal RXb received via the capacitor 31b to the AD converter 322b.
The AD converter 322 b converts the modulated audio signal RAb into a modulated audio data
signal RDb in digital form, and supplies it to the demodulation circuit 323 b. The demodulation
circuit 323b subjects the modulated audio data signal RDb to demodulation processing
corresponding to digital modulation in the modulation circuit 136 of the transmission signal
processing unit 13 described above, to obtain frame audio having a data format as shown in FIG.
The signal is restored and supplied to the data extraction circuit 334b as a frame audio signal
FRb.
[0051]
The data extraction circuit 334b extracts the audio data signal CDD, the volume adjustment data
VOLb, the phase adjustment data PCb, and the reproduction band setting data FCb from each
frame in the frame audio signal FRb as shown in FIG. Then, the data extraction circuit 334b
supplies the audio data signal CDD to the error correction circuit 335b, and supplies the volume
adjustment data VOLb, the phase adjustment data PCb and the reproduction band setting data
FCb to the control signal generation circuit 336b. The error correction circuit 335b performs
error correction processing on the audio data signal CDD to generate an audio data signal VDb in
which error bits are corrected, and supplies the audio data signal VDb to the variable filter 337b.
[0052]
The control signal generation circuit 336 b should set the band pass characteristic of the variable
filter 337 b to the band pass characteristic specified by the reproduction band setting data FCb,
for example, the band pass characteristic transmitting only the reproduction frequency band fb
of FIG. 3. The filter coefficient Kb is supplied to this variable filter 337b. Furthermore, the control
signal generation circuit 336b generates a gain adjustment signal VLb whose gain should be
adjusted by an amount corresponding to the volume adjustment amount indicated by the volume
adjustment data VOLb, and supplies this to the class D amplifier 33b. Further, the control signal
generation circuit 336 b indicates the phase adjustment data PCb as an offset delay time Tof1 for
absorbing a time difference between output channels (for example, right and left channels) in the
09-05-2019
17
audio data signal CDD in each frame. A delay control signal DLb indicating a delay time obtained
by adding the desired phase adjustment value is supplied to the variable delay circuit 338b. In
the example shown in FIG. 1, the output channel is only for one channel consisting of the speaker
4a as a woofer and the speaker 4b as a tweeter, so as shown in FIG. 8, the reception signal
processing units 32a and 32b are identical. The offset delay time Tof1 is used.
[0053]
The variable filter 337 b is, for example, a digital band pass filter including an FIR filter or the
like. The variable filter 337 b performs filtering on the audio data signal VDb supplied from the
error correction circuit 335 b with a band bus characteristic corresponding to the abovedescribed filter coefficient Kb to provide the variable delay circuit 338 b with the audio data
signal QDb. Supply. That is, according to the filter coefficient Kb, the variable filter 337b
transmits only the high frequency components included in the reproduction frequency band fb of
FIG. 3 out of the audio data signal VDb, and changes this as the audio data signal QDb. It supplies
the circuit 338b. The variable delay circuit 338b delays the audio data signal QDb by the delay
time indicated by the delay control signal DLb to generate an audio data signal AGb, which is
supplied to the class D amplifier 33b.
[0054]
As described above, in the audio system employing the transmission signal processing unit 13
having the internal configuration shown in FIG. 6 and the reception signal processing units 32a
and 32b having the internal configuration shown in FIG. A variable filter 337a is provided in the
reception amplifier 3a as a network, and a variable filter 337b is provided in the reception
amplifier 3b as a high frequency side dividing network for a speaker. At this time, according to
such a configuration, the band pass characteristics of each of the variable filters 337a and 337b
can be individually set by the reproduction band setting data FCa and FCb transmitted from the
audio signal transmission unit 1 side. Thus, even if the speaker 4a used as a woofer or the
speaker 4b used as a tweeter is changed to another speaker, band division corresponding to the
reproduction frequency band of the speaker after change is performed by the reproduction band
setting data FCa and FCb. It is possible to save the trouble of changing the filter because it is
possible.
[0055]
09-05-2019
18
Further, in the audio system adopting the configuration shown in FIGS. 6 and 7, the variable
delay circuit 338a is provided in the reception signal processing unit 32a on the woofer side, and
the variable delay circuit 338b is provided in the reception signal processing unit 32b on the
tweeter side. The amount of delay of each of the delay circuits 338a and 338b can be
individually changed by the phase adjustment data PCa and PCb transmitted from the audio
signal transmission unit 1. Therefore, according to the adjustment of the delay amount using the
phase adjustment data PCa and PCb, it is possible to perform phase adjustment to make the
phases of the sounds emitted from the speaker 4a as the woofer and the speaker 4b as the
tweeter equal. Can provide a good sound field.
[0056]
Here, when the modulated audio signal TX is transmitted to each of the receiving amplifiers 3a
and 3b via the transmission cable 2, the larger the amplitude of the modulated audio signal TX,
the larger the noise radiated from the transmission cable 2. Therefore, in order to reduce the
radiation noise from the transmission cable 2, the amplitude of the modulated audio signal TX
may be reduced to such an extent as not to affect the transmission.
[0057]
FIG. 9 is a block diagram showing another configuration of the audio system made in view of the
above point. In the audio system shown in FIG. 9, the transmission output control unit 16 is
provided in the audio signal transmission unit 1, and the transmission output control unit 35a
(35b) is provided in the reception amplification unit 3a (3b). The other configuration is the same
as that shown in FIG. 1 except that the transmission signal processing unit 130 is employed
instead of the unit 13 and the reception signal processing unit 320a (320b) is employed instead
of the reception signal processing unit 32a (32b). It is. At this time, in the audio signal
transmission unit 1, the output end of the transmission signal processing unit 130, one end of
the capacitor 14 and the input end of the transmission output control unit 16 are commonly
connected by a line L1. On the other hand, in the reception amplification unit 3a (3b), one end of
the capacitor 31a (31b), the input end of the reception signal processing unit 320a (320b), and
the output end of the transmission output control unit 35a (35b) are line L2a (L2b) Are
connected in common.
[0058]
09-05-2019
19
FIG. 10 is a block diagram showing an internal configuration of the transmission output control
unit 35a and the reception signal processing unit 320a included in the reception amplification
unit 3a shown in FIG. In FIG. 10, the received signal processing unit 320a employs a
demodulation circuit 343a instead of the demodulation circuit 323a and an error correction
circuit 345a instead of the error correction circuit 325a. It is identical to that shown in.
Therefore, only the operations of the demodulation circuit 343a and the error correction circuit
345a will be described for the reception signal processing unit 320a shown in FIG.
[0059]
The demodulation circuit 343a generates a frame audio signal FRa by performing demodulation
processing corresponding to digital modulation in the modulation circuit 136 described above on
the modulated audio data signal RDa supplied from the AD converter 322a. Are shared by the
data extraction circuit 324a. Further, the demodulation circuit 343a detects an error ratio of
digital modulation in the modulated audio data signal RDa, so-called MER (Modulation Error
ratio), or EVM (Error Vector Magnitude) indicating modulation accuracy, and uses this as a first
transmission quality evaluation value. Are supplied to the transmission output control unit 35a.
[0060]
The error correction circuit 345a performs an error correction process on the audio data signal
CDD supplied from the data extraction circuit 334a to generate an audio data signal VDa in
which an error bit is corrected, and sends it to the variable delay circuit 327a. Supply.
Furthermore, the error correction circuit 345a detects an error bit rate by such error correction
processing, so-called BER (Bit Error Ratio) or total number of error bits, and indicates a second
transmission quality evaluation data signal Q2 indicating this as a second transmission quality
evaluation value. Are supplied to the transmission output control unit 35a.
[0061]
As shown in FIG. 10, the transmission output control unit 35a includes a transmission quality
determination circuit 351a, a transmission output control signal generation circuit 352a, a
modulation circuit 353a, a DA converter 354a, and a transmission amplifier 355a. The
09-05-2019
20
transmission quality judgment circuit 351a judges the degree of transmission quality in
communication via the transmission cable 2 based on the first transmission quality evaluation
data signal Q1 and the second transmission quality evaluation data signal Q2. For example, the
transmission quality degree indicates that the transmission quality is higher as the error bit rate
indicated by the first transmission quality evaluation data signal Q1 is lower and the digital
modulation error ratio indicated by the second transmission quality evaluation data signal Q2 is
smaller. The data is supplied to the transmission output control signal generation circuit 352a.
The transmission output control signal generation circuit 352a lowers the transmission output as
the transmission quality indicated by the transmission quality degree data is higher, but
generates the transmission output control signal PCD to increase the transmission output as the
transmission quality is lower. The signal is supplied to the modulation circuit 353a. The
modulation circuit 353a supplies a modulation transmission output control signal PQD obtained
by performing digital modulation such as QPSK modulation or QAM on the transmission output
control signal PCD to the DA converter 354a. The DA converter 354a converts the modulated
transmission output control signal PQD into a modulated transmission output control signal PQ
of an analog signal, and supplies this to the transmission amplifier 355a.
[0062]
The transmission amplifier 355a amplifies the modulated transmission output control signal PQ
to generate a modulated transmission output control signal PHa, and generates the modulated
transmission output control signal PHa within the idle time GA between adjacent frames in the
modulated audio signal TX as shown in FIG. The audio signal is transmitted to the audio signal
transmitter 1 via the line L 2 a and the transmission cable 2.
[0063]
Here, the transmission output control unit 35b and the reception signal processing unit 320b in
the reception amplification unit 3b illustrated in FIG. 9 have the same internal configuration as
the transmission output control unit 35a and the reception signal processing unit 320a
illustrated in FIG.
However, the transmission amplifier 355b (corresponding to the transmission amplifier 355a) in
the transmission output control unit 35b in the reception amplification unit 3b transmits the
modulated transmission output control signal PHa by the transmission amplifier 355a in the idle
time GA as shown in FIG. And transmit the modulated transmission output control signal PHb to
the audio signal transmitter 1 via the transmission cable 2. That is, the modulated transmission
output control signal PHa output from the transmission output control unit 35a of the reception
09-05-2019
21
amplification unit 3a and the modulated transmission output control signal PHb output from the
transmission output control unit 35b of the reception amplification unit 3b are shown in FIG. As
shown, the signal is sequentially transmitted to the audio signal transmitter 1 via the single
transmission cable 2 within the idle time GA.
[0064]
FIG. 12 is a block diagram showing an internal configuration of each of the transmission output
control unit 16 and the transmission signal processing unit 130 provided in the audio signal
transmission unit 1. The internal configuration of the transmission signal processing unit 130 is
the same as that shown in FIG. 6 except that the variable gain transmission amplifier 238 is
employed instead of the transmission amplifier 138. On the other hand, as shown in FIG. 12, the
transmission output control unit 16 includes a reception amplifier 161, an AD converter 162, a
demodulation circuit 163, and a gain setting circuit 164. The reception amplifier 161 receives
the modulated transmission output control signal PHa or PHb transmitted from the reception
amplification unit 3a or 3b shown in FIG. 9 via the transmission cable 2 and amplifies the
modulated transmission output control signal PS. Supply to the The AD converter 162 converts
the modulation transmission output control signal PS into a modulation transmission output
control data signal PMD of a digital value, and supplies this to the demodulation circuit 163. The
demodulation circuit 163 subjects the modulated transmission output control data signal PMD to
demodulation processing corresponding to digital modulation in the modulation circuit 353a
(353b) described above, thereby restoring the transmission output control signal described
above and transmitting it. It is supplied to the gain setting circuit 164 as the output control
signal PD. Gain setting circuit 164 includes a transmission output control signal PD
corresponding to modulated transmission output control signal PHa from reception amplification
unit 3a and a transmission output control signal PD corresponding to modulation transmission
output control signal PHb from reception amplification unit 3b. Within, select the one that shows
high transmit power. That is, the gain setting circuit 164 transmits the transmission output
control signal PD corresponding to the modulated transmission output control signal (PHa or
PHb) transmitted from the reception amplification unit 3 having the lower transmission quality
from the reception amplification units 3a and 3b. select. Then, the gain setting circuit 164
generates a gain signal PG indicating a gain according to the size of the transmission output
indicated by the selected transmission output control signal PD, and outputs this as a variable
gain transmission amplifier of the transmission signal processing unit 130. Supply to 238. That
is, as the transmission output indicated by the transmission output control signal PD is lower, the
gain setting circuit 164 supplies the variable gain transmission amplifier 238 with the gain signal
PG indicating the gain for which the amplitude of the modulated audio signal TX should be
reduced. Variable gain transmission amplifier 238 amplifies modulated audio signal TX obtained
by amplifying modulated audio signal MA supplied from DA converter 137 with a gain indicated
09-05-2019
22
by gain signal PG, through line L 1, capacitor 14 and transmission cable 2. And transmit to the
reception amplification units 3a and 3b.
[0065]
Thus, in the audio system shown in FIGS. 9 to 12, the transmission quality (MER) of the reception
amplification unit (3a, 3b) is determined based on the reception modulated audio signal (RXa,
RXb) received via the transmission cable 2. , BER). Next, the reception amplifier (3a, 3b)
generates a transmission output control signal (PCD) to decrease the transmission output, that is,
the amplitude of the modulated audio signal TX as the transmission quality is higher, and
performs modulation on this Modulated transmission output control signals (PHa, PHb) are
transmitted to the audio signal transmitter 1 via the transmission cable 2. The audio signal
transmission unit 1 receives the modulated transmission output control signals (PHa and PHb)
and subjects the modulated transmission output control signals (PHa and PHb) to demodulation
processing to restore the transmission output control signal (PD). Then, the audio signal
transmission unit 1 reduces the gain of the transmission amplifier (238) that transmits the
modulated audio signal TX as the transmission output indicated by the transmission output
control signal (PD) is lower. That is, the transmission quality is determined based on the
modulated audio signal received by the reception amplification unit (3a, 3b), and the amplitude
of the modulated audio signal TX to be transmitted in the audio signal transmission unit 1 should
be reduced as the transmission quality is higher. It controls. As a result, it is possible to reduce
the radiation noise by suppressing the amplitude of the modulated audio signal TX while
maintaining the transmission quality to the extent that the transmission is not disturbed.
[0066]
The above embodiment shows a configuration in which a speaker system for one channel
consisting of a reception amplifier 3a and a speaker 4a responsible for bass reproduction and a
reception amplifier 3b and a speaker 4b responsible for high frequency reproduction is
connected to the transmission cable 2. However, it is also possible to adopt a configuration in
which speaker systems of two or more channels for left and right channels or three or more
channels are connected to the transmission cable 2. For example, as shown in FIG. 13, speaker
systems for one channel consisting of the reception / amplification units 3 a and 3 b and the
speakers 4 a and 4 b as described above are prepared for two channels on the left and right.
Connect to the audio signal transmitter 1. At this time, as shown in FIG. 14, the audio signal
transmitting unit 1 outputs an audio data signal CDD for the right channel, control data signals
(VOLa, FCa, PCa, VOLb, FCb, PCb) and an audio data signal for the left channel. A modulated
09-05-2019
23
audio signal TX is generated by modulating a frame audio signal FA in which the CDD and the
control data signal are arranged in order. Then, the audio signal transmission unit 1 transmits
the modulated audio signal TX to the right channel speaker system (3a, 4a) and the left channel
speaker system (3b, 4b) via the transmission cable 2. The data extraction circuit 334a of the
reception amplification unit 3a for the right channel extracts the control data signal (VOLa, FCa,
PCa) corresponding to the right channel and the audio data signal CDD from the frame audio
signal as shown in FIG. . The data extraction circuit 334b of the reception amplification unit 3b
for the right channel extracts the control data signal (VOLb, FCb, PCb) corresponding to the right
channel and the audio data signal CDD from the frame audio signal, as shown in FIG. . The data
extraction circuit 334a of the reception amplification unit 3a for the left channel extracts the
control data signal (VOLa, FCa, PCa) corresponding to the left channel and the audio data signal
CDD from the frame audio signal as shown in FIG. . The data extraction circuit 334b of the
reception amplification unit 3b for the left channel extracts the control data signal (VOLb, FCb,
PCb) corresponding to the left channel and the audio data signal CDD from the frame audio
signal as shown in FIG. . At this time, in the reception amplification units 3a and 3b of the right
channel and the reception amplification units 3a and 3b of the left channel, various controls as
described above are executed based on the control data signal acquired by each.
For example, as shown in FIG. 14, the reception amplification unit 3a (3b) of the right channel
uses the phase adjustment data PCa in the offset delay time Tof1 for absorbing the time
difference between the CDD for the right channel and the CDD for the left channel. A signal
obtained by delaying the CDD for the right channel by a delay time obtained by adding the phase
adjustment value indicated by (PCb) is supplied to the speaker 4a (4b) as AGa (AGb). The offset
delay time Tof1 is a delay time for the right channel CDD set to eliminate the time difference
between the leading portions of the right channel CDD and the left channel CDD separated by
time division multiplexing. is there. Further, as shown in FIG. 14, the phase adjustment data PCa
(the offset amplification time Tof2 for absorbing the time difference between the CDD for the
right channel and the CDD for the left channel) of the reception amplification unit 3a (3b) for the
left channel. A signal obtained by delaying the CDD for the left channel by the delay time
obtained by adding the phase adjustment value indicated by PCb) is supplied to the speaker 4a
(4b) as AGa (AGb). The offset delay time Tof2 is a delay time for the left channel CDD set to
eliminate the time difference between the leading portions of the right channel CDD and the left
channel CDD separated by time division multiplexing. is there.
[0067]
In short, a reception amplification unit is provided for each of M (M is a natural number of 2 or
more) speakers, and an audio signal transmission unit multiplexes a control data signal and an
09-05-2019
24
audio data signal to individually control each reception amplification unit. The modulated audio
signal that has been modulated is transmitted to each of the reception amplification units via a
single transmission cable to which a DC power supply voltage is applied. At this time, each
reception amplification unit is driven by the power supply voltage supplied through the
transmission cable, and performs the following operation. That is, the reception amplification
unit demodulates the control data signal and the audio data signal described above from the
received modulated audio signal, and the amplified audio signal subjected to control according to
the control data signal to the audio data signal is a speaker Supply to
[0068]
DESCRIPTION OF SYMBOLS 1 audio signal transmission part 2 transmission cable 3a, 3b
reception amplification part 4a, 4b speaker 13 transmission signal processing part 15 power
supply voltage production | generation part 32a, 32b received signal processing part 33a, 33b D
class amplifier 34a, 34b power supply voltage derivation part 135 frame Generation circuit 136
modulation circuit 323a, 323b demodulation circuit
09-05-2019
25
Документ
Категория
Без категории
Просмотров
1
Размер файла
41 Кб
Теги
jp2015015618
1/--страниц
Пожаловаться на содержимое документа