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DESCRIPTION JP2007060229

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DESCRIPTION JP2007060229
PROBLEM TO BE SOLVED: To improve the quality of a speech signal by controlling an echo /
noise cancellation condition for a speech signal according to the noise environment in a vehicle
compartment, so that the other party of communication can easily make the voice of a passenger
in the vehicle room uncomfortably Make it audible. SOLUTION: Either an echo component
generated in a transmission signal when a reception signal from a speaker 3 is inputted to a
microphone 2 or any noise component contained in the transmission signal according to a noise
environment in a vehicle compartment Alternatively, either the echo component or the noise
component is canceled by the cancel circuits 31 and 312 in the direction in which the signal
quality of the transmission signal is improved according to the cancel circuits 31 and 312
canceling both and the noise environment in the vehicle room deteriorates. It comprises so that
the control means 50 which controls the gain about the transmission signal which canceled one
or both sides may be provided. [Selected figure] Figure 1
In-vehicle hands-free handset
[0001]
The present invention relates to an on-vehicle hands-free communication device.
[0002]
For example, Japanese Patent Application Laid-Open No. 6-3009 (hereinafter referred to as
Patent Document 1), Japanese Patent Application Laid-open No. 5-14475 (hereinafter referred to
as Patent Document 2), and Japanese Patent Application Laid-Open 7-321729 (hereinafter
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1
referred to Patent Document 3) and Japanese Patent Application Laid-Open No. 2004-96664
(hereinafter referred to as Patent Document 4).
First, the technique of Patent Document 1 detects ambient noise with a noise detection circuit to
which the output from the microphone is supplied, and changes the frequency characteristics of
the reception filter circuit based on the detection result. More specifically, ambient noise In a
large situation, the low frequency component is emphasized and the voice from the other party is
reproduced by the speaker (the low frequency emphasis may be applied to the transmission
signal). As a result, it is possible to obtain good call quality even under high noise without
howling or without interruption of the call.
[0003]
Further, according to the technology disclosed in Patent Document 2, in a loudspeaker telephone
having a noise canceller for canceling a moving object traveling noise signal from a microphone,
the noise canceller comprises noise signal generating means for generating a pseudo noise signal
according to the traveling speed of the moving object; A noise canceller adaptive digital filter for
estimating a transfer characteristic from the noise source of the mobile unit to the microphone
using the pseudo noise signal as a reference signal and outputting a noise cancellation signal
when the near end speaker voice signal is not input; And an adder for subtracting the noise
cancellation signal from the moving object traveling noise signal. As a result, it is possible to
cancel the actual running noise mixed in from the microphone, and by sending the signal after
the running noise cancellation to the echo canceller, it is possible to stabilize the echo
cancellation operation. Therefore, since there is no sense of acoustic echo or howling, and the
traveling noise is not transmitted to the far-end talker side, a natural, high-quality hands-free call
can be made.
[0004]
Furthermore, the technique of Patent Document 3 estimates the noise level and the frequency
characteristics in the vehicle compartment based on the detection information from various
sensors such as a vehicle speed sensor and an acceleration sensor, and the received sound is
protected from the noise and echo. It controls the volume and frequency characteristics. As a
result, it is possible to automatically adjust and maintain the state of the reception sound to be
always appropriate to the surrounding environment, and to provide the user with a sound field
that is truly easy to hear.
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[0005]
Further, the technique of Patent Document 4 is that when a hands-free call is performed in a
hands-free communication device, a mask sound (a characteristic close to music or air
conditioner ventilation sound that masks the call sound directed to the driver from the first
speaker The second speaker outputs a sound having characteristics, a sound having
characteristics close to road noise (traveling sound, etc.) to a passenger. As a result, it is possible
to suppress privacy from being heard by the other party in the passenger seat and to realize
privacy protection and confidentiality. In the case of music, the above-mentioned mask sound
indicates that the car audio is playing music in the case of music, that the car air conditioner is in
the ON state in the case of the sound having characteristics close to the air conditioner
ventilation sound, and the car in the case of road noise. Is detected when each detects that the
vehicle is traveling. JP-A-6-30090 JP-A-5-14475 JP-A-7-321729 JP-A 2004-96664
[0006]
However, in the above-described prior art, the parameters that determine the performance of
hands-free calling, in particular, the settings (canceling conditions) of the echo cancellation
circuit and the noise cancellation circuit for the transmission signal are fixed, depending on the
noise environment of the vehicle interior. It did not change. For this reason, for example, even if
the noise environment of the vehicle interior changes (deteriorates), such as a state where the
window of the vehicle is open, a state where the air volume in the vehicle interior is large, or a
high speed traveling state, appropriate echo or noise according to it A cancellation process may
not be performed, and the quality of the transmission signal may deteriorate to make it difficult
for the other party to hear. In this case, even if the volume of the transmission signal is simply
increased, the quality remains poor, and no improvement can be expected.
[0007]
Further, when the window of the vehicle is open, the echo cancellation circuit hardly functions
because the interior of the vehicle is in an environment where echo is less likely to occur. In this
case, the reception volume can be increased compared to the state where the window is closed.
However, in the above-mentioned prior art, since such a difference in echo environment in the
vehicle compartment is not taken into consideration, the adjustment of the reception volume
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(variable range of the reception volume) suitable for the vehicle interior environment is
necessarily realized. It can not be said.
[0008]
The present invention has been made in view of the problems as described above, and improves
the quality of the transmission signal by controlling the echo / noise cancellation condition for
the transmission signal according to the noise environment in the vehicle compartment (echo An
object of the present invention is to make it possible for the other party to easily hear the inroom caller's voice without a sense of discomfort by reducing or reducing the noise. Another
object of the present invention is to make it possible to adjust the voice transmission volume and
the reception volume appropriately according to the vehicle interior environment in
consideration of the difference in echo environment in the vehicle interior, and to make the voice
of the other party easier to hear.
[0009]
In order to achieve the above object, the on-vehicle hands-free communication device (claim 1)
outputs a microphone to which a call transmission signal from the in-vehicle caller to the call
partner is input and a reception signal from the call partner Speaker, an echo component
generated in the transmission signal when the reception signal from the speaker is input to the
microphone, and any noise component included in the transmission signal according to the noise
environment in the vehicle compartment The transmission circuit according to a cancellation
circuit for canceling one or both, a noise environment detection means for detecting a noise
environment in the vehicle compartment, and the noise environment detected as a result of the
noise environment detection means. Control for controlling the gain of the transmission signal in
which one or both of the echo component and the noise component are canceled by the
cancellation circuit in the direction in which the signal quality of the signal is improved It is
characterized in that equipped the stage.
[0010]
Here, the noise environment detection means is configured as a window open / close state
detection means for detecting the open / close state of the window of the vehicle, and the control
means detects the open state of the window by the window open / close state detection means It
may be configured to control the gain when it is made (claim 2).
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Further, the noise environment detection means is configured as an air conditioning equipment
operation load detection means for detecting the operation load of the air conditioning
equipment in the vehicle compartment, and the control means is an operation detected by the air
conditioning equipment operation load detection means. It may be configured to control the gain
according to the load (claim 3).
[0011]
Furthermore, the noise environment detection means is configured as a traveling speed detection
means for detecting the traveling speed of the vehicle, and the control means controls the gain
according to the traveling speed detected by the traveling speed detection means. It may be
configured to do this (claim 4). Further, the apparatus further comprises a volume adjustment
circuit for adjusting the volume of one or both of the transmission signal and the reception
signal, and the control unit detects the open state of the window by the window open / close
state detection unit. The volume control circuit may be configured to control the volume control
circuit so that the volume of one or both of the transmission signal and the reception signal is
higher than the volume when the window is closed. Claim 5).
[0012]
Furthermore, a receiver volume control circuit for adjusting the volume of the receiver signal is
further provided, and the control means increases the volume of the receiver signal in response
to deterioration of the noise environment detected by the noise environment detector. It may be
configured to control the reception volume control circuit to become (claim 6). Further, the onvehicle hands-free communication device (claim 7) according to the present invention is a
microphone for receiving a speech signal from a passenger in a car room to a communication
partner, a speaker for outputting a reception signal from the communication partner, An echo
canceler that cancels an echo component generated in the transmission signal when the
reception signal from the speaker is input to the microphone; and adjusting the volume of one or
both of the transmission signal and the reception signal A volume control circuit, echo
environment detecting means for detecting whether the echo component is less likely to occur in
the vehicle interior space, and an environment in which the vehicle interior space is less likely to
generate the echo component in the echo environment detecting means When it is detected that
the volume of either or both of the transmission signal and the reception signal is in an
environment in which the echo component is likely to occur. It is characterized in that and a
control means for controlling the sound volume adjustment circuit to be larger than the volume.
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[0013]
Here, the echo environment detection means is configured as a window open / close state
detection means for detecting that the window of the vehicle is in an open state as an
environment in which the echo component is less likely to be generated, and the control means is
the window When the open state of the window is detected by the open / close state detection
means, the volume of either or both of the transmission signal and the reception signal is higher
than that when the window is closed. It may be configured to control the volume adjustment
circuit (claim 8).
[0014]
According to the present invention, in response to the noise in the vehicle becoming large and
the noise environment becoming worse, either or both of the echo component and the noise
component are canceled by the cancellation circuit in the direction in which the signal quality of
the transmission signal is improved. Since the gain of the transmission signal for which the
cancellation of the above has been canceled is controlled, the voice of the driver can be heard
without a sense of incongruity, for example, the noise can be reduced and the echo can be
reduced on the opposite side.
[0015]
In addition, since it is possible to adjust the transmission volume and the reception volume
appropriately according to the vehicle interior environment in consideration of the difference in
echo environment in the vehicle interior, it becomes easier to hear the voice of the other party.
[0016]
[A] Description of an Embodiment FIG. 1 is a block diagram showing a main configuration of an
on-vehicle hands-free communication device according to an embodiment of the present
invention. The on-vehicle hands-free communication device 1 shown in FIG. A microphone 2 to
which a speech signal is input from a passenger in the vehicle room such as a hand to a
telephone 5 of the other party (hereinafter, may be referred to as the other party 5), and a
reception signal from the other party 5 A speaker 3 for output, a transmission processing unit 30
for performing required transmission processing including echo cancellation and noise
cancellation on the transmission signal, and a reception processing unit 40 for performing
required reception processing for the reception signal A controller 50 is provided to integrally
control the processes of the transmission processing unit 30 and the reception processing unit
40.
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[0017]
Although not shown in FIG. 1, the transmission processing unit 30 is connected to a transmission
radio unit such as a modulator, a frequency converter (up converter), a transmission antenna, etc.
Are connected to a reception radio unit such as a demodulator, a frequency converter (down
converter), and a reception antenna (also used as the above transmission antenna).
The transmission processing unit 30 further includes an amplifier 301, analog filters 302 and
320, an analog to digital converter (ADC: analog to digital converter), digital filters 304 and 318,
variable gain circuits 305, 308 and 311, and the like. Reference numerals 314 and 317, noise
canceller 312, slope filter 315, digital to analog converter (DAC) 319, switches 307, 313, and
316, and an echo canceller (echo cancel circuit) 31, which constitutes FIR (Finite) (Impulse
Response) filter 309, howling / double talk detector 310 and adder 306 are provided, and the
above-mentioned reception processing unit 40 comprises analog filters 401, 409, ADC 402,
digital filters 403, 407, gain available Circuit 404 and 405, and is configured to include a switch
406 and a DAC 408.
[0018]
Here, in the transmission processing unit 30, the amplifier 301 amplifies a transmission signal
from the microphone (hereinafter may be simply referred to as a "microphone") 2 to a desired
signal level, and is analog The filter 302 removes unnecessary frequency components included in
the transmission signal from the amplifier 301, and the ADC 303 converts the output of the
analog filter 302 into a digital signal.
[0019]
The digital filter 304 is for removing unnecessary components (mainly noise components
generated at the time of digital conversion in the ADC 303) contained in the digital transmission
signal obtained by the ADC 303, and the variable gain circuit 305 The gain setting is performed
to adjust the gain of the digital transmission signal passed through the digital filter 304, and the
output is branched into two systems and input to the switch 307.
[0020]
The adder 306 is a component of the echo canceller 31 and is interposed in one of the branched
signal systems, and is adaptively estimated by the digital transmission signal as the output of the
variable gain circuit 305 and the FIR filter 309. A system that cancels (suppresses) an acoustic
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echo component (echo component generated by the output of the speaker 3 coming into the
microphone 2 and being input) contained in the digital transmission signal by adding the pseudo
echo component It is.
[0021]
The switch 307 selectively outputs one of the digital transmission signals branched into the
above two systems, that is, selectively switches a system to which echo cancellation is to be
performed by the adder 306 and a system to which echo cancellation is not performed. .
The switching is controlled by the controller 50.
That is, in the transmission processing unit 30, the presence or absence of echo cancellation for
the transmission signal can be appropriately changed according to the setting from the controller
50.
[0022]
The gain variable circuit 308 is for adjusting the gain of the output (digital transmission signal)
of the switch 307 according to the setting from the controller 50, and together with the gain
variable circuit 305, the echo canceler 31 is used to The gain of the digital transmission signal
before and after cancellation can be adjusted appropriately.
The noise canceller (noise cancel circuit) 312 cancels (suppresses) the noise component
contained in the digital transmission signal, for example, the noise component contained in
accordance with the noise environment in the vehicle compartment, and the gain variable circuits
311 and 314 The gain of the digital transmission signal before and after the noise cancellation
by the noise canceller 312 is controlled (adjusted) in accordance with the setting from the
controller 50.
[0023]
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The switch 313 selectively switches between a system that performs noise cancellation by the
noise canceler 312 and a system that does not cancel noise according to the setting from the
controller 50. The slope filter 315 is a noise component included in the digital transmission
signal. Mainly, it is intended to remove vehicle-specific noise components such as road noise and
engine noise.
The switch 316 selectively switches between a system that performs noise removal by the slope
filter 315 and a system that does not remove noise according to the setting from the controller
50. The gain variable circuit (transmission volume control circuit) 317 is By controlling the gain
of the digital transmission signal from the switch 316 according to the setting from the controller
50, it functions as a transmission volume control circuit for adjusting the transmission volume to
the other party.
[0024]
The digital filter 318 is for removing unnecessary components included in the digital
transmission signal after gain adjustment by the gain variable circuit 317, and the DAC 319
converts the digital transmission signal into an analog signal (analog transmission signal). The
analog filter 320 is for removing unwanted components (mainly, noise components generated at
the time of analog conversion in the DAC 319) included in this analog transmission signal.
[0025]
Further, in the echo canceller 31, an FIR filter (adaptive filter) 309 generates a pseudo echo
signal for nulling the signal passed through the adder 306, that is, the echo signal (residual
signal), and is adapted The acoustic characteristics (echo path) of the vehicle interior space are
estimated by the operation, and the pseudo echo signal is generated based on the estimation
result and the reception signal in the reception processing unit 40.
[0026]
The howling / double talk detector 310 compares the transmission signal level and the reception
signal level, and determines whether the speech state is the transmission state or the reception
state or both states (double talk state). It is possible to detect the howling state as well as the
howling state, and when the double talk state or the howling state is detected, the controller 50
controls the gain variable circuit 405 in the reception processing unit 40 and the reception is
output from the speaker 3 By adjusting the volume, these states can be avoided.
[0027]
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The echo canceller 31 (FIR filter 309, howling / double talk detector 310, and adder 306 can be
configured using, for example, a DSP (Digital Signal Processor) or the like.
On the other hand, in the reception processing unit 40, the analog filter 401 is for removing
unnecessary frequency components and the like included in the reception signal (analog
reception signal) from the communication partner 5, and the ADC 402 passes through the analog
filter 401. The digital filter 403 is an unnecessary component included in the digital reception
signal obtained by the ADC 402 (mainly noise generated during digital conversion in the ADC
402). Component) is to be removed.
[0028]
A gain variable circuit (reception volume control circuit) 404 is output from the speaker 3 into
the vehicle compartment by controlling (adjusting) the gain of the digital reception signal passed
through the digital filter 403 according to the setting from the controller 50. The gain variable
circuit 405 is for adjusting the reception volume, and adjusts the gain of the digital reception
signal in accordance with the control from the howling / double talk detector 310 as described
above.
[0029]
The switch 406 selectively switches between a system performing gain adjustment by the
variable gain circuit 405 and a system not performing the same according to the setting from the
controller 50, and the digital filter 407 receives a digital reception from the switch 406. The DAC
408 is for removing unnecessary components contained in the signal, and the DAC 408 converts
the digital reception signal passed through the digital filter 407 into an analog reception signal,
and the analog filter 409 is obtained by the DAC 408. It further removes unnecessary
components (mainly, noise components generated at the time of analog conversion in the DAC
408) included in the analog reception signal.
[0030]
The controller 50 controls the gain variable circuits 305, 308, 311, 314, 317, 404 and the
switches 307, 313, 316, 406 as described above, and in the present embodiment, the following
functions are also performed. Have.
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(1)In response to the digital transmission signal between the digital filter 318 and the DAC 319
in the transmission processing unit 30 (the portion indicated by the symbol A in FIG. 1), the peak
value of the transmission signal level is detected, A transmission signal level detection function
that detects the level of no sound during ringing or when the vehicle-side telephone is ringing.
[0031]
(2)
Reception volume detection that detects a reception volume level by receiving a digital reception
signal between the digital filter 407 and the DAC 408 (portion indicated by symbol B in FIG. 1) in
the reception processing unit 40 and detecting the signal level function.
(3)Transmission signal noise that receives a digital transmission signal between the digital filter
304 and the gain variable circuit 305 in the transmission processing unit 30 (the portion
indicated by a symbol C in FIG. 1) and detects the amount of noise included in the signal
Detection function.
[0032]
(4)
Noise environment detection to detect the noise environment of the vehicle interior such as the
traveling speed of the vehicle, the open and closed states of windows (including various windows
such as the driver's seat, the passenger's seat, both sides of the rear seat and the ceiling)
Function (noise environment detection means).
That is, as shown in FIG. 1, the controller 50 is connected to, for example, the air conditioner 51,
the opening / closing mechanism detection circuit 52, and the vehicle speed sensor 53, and can
detect the vehicle environment as described above.
In other words, the controller 50 has a function as window open / close state detection means for
detecting the open / close state of the window of the vehicle, a function as air conditioning
facility operation load detection means for detecting the operation load of the air conditioning
facility in the vehicle compartment, A function as a traveling speed detecting means for detecting
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the traveling speed of the vehicle, etc. is provided selectively or in combination.
[0033]
(5)
A transmission volume correction function that corrects the transmission signal level
(transmission volume) by controlling the gain variable circuit 317 according to the peak value of
the transmission signal level detected by the transmission signal level detection function of (1)
above .
By providing the controller 50 with a voice recognition means (not shown), for example, the
voice of the in-vehicle caller such as the driver can be recognized as "Hello" and the speech can
be detected twice to transmit the voice. The gain of the variable gain circuit 317 is controlled to
increase the volume.
That is, when the call start is detected, the transmission volume can be controlled to be
automatically increased.
[0034]
(6)
A noise canceller according to the minimum value of the transmission signal level (noise amount
in the passenger compartment) during silence (in the non-talking period) or the level of the
transmission signal level during conversation detected by the transmission signal level detection
function of (1) above The gain variable circuits 311 and 314 interposed before and after 312 are
controlled to correct the transmission signal level, and the gain variable circuit 311 according to
the noise environment detected by the noise environment detection function of the above (4),
Noise removal correction function to change the gain of 314 to a preset value. For example,
when the amount of noise is large, the switch 313 can be switched to the side of the noise
canceller 312 to control the gain variable circuits 311 and 314 so that the transmission signal
level after noise cancellation by the noise canceller 312 becomes large.
[0035]
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Further, the variable gain circuits 311 and 314 can be controlled to automatically increase the
transmission signal level even when the voice of the speaker is small. In addition, even when the
noise environment is deteriorated, such as when the traveling speed is high, the window is open,
or the air volume of the air conditioner is large, the transmission signal is automatically
transmitted according to the deterioration of the noise environment. The variable gain circuits
311 and 314 can be controlled to increase the level stepwise or continuously.
[0036]
(7)
1 for a certain period of time during a conversation, sampling the signal of the portion indicated
by symbol A in FIG. 1 to detect an echo amount, and controlling the gain variable circuits 305,
308, and 405 according to the echo amount. Echo correction function to correct transmission
signal level. For example, when the amount of echo is large, the switch 307 is switched to the
echo canceller 31 side and the echo canceler 31 cancels the echo while decreasing the gain of
the gain variable circuit 405 to reduce the amount of echo coming around to the microphone 2.
The variable gain circuits 305 and 308 can be controlled so that the transmission signal level
increases stepwise or continuously. Also in this case, it is preferable to control to lower the gain
of the former stage variable gain circuit 305 while increasing the gain of the latter stage variable
gain circuit 308.
[0037]
(8)For example, the noise amount between the digital filter 304 on the side of the transmission
processing unit 30 and the gain variable circuit 305 (the portion indicated by a symbol C in FIG.
1) by sampling for a certain period during conversation after the start of the call The received
signal level (that is, the speaker volume) between the digital filter 407 on the reception
processing unit 40 side and the DAC 408 (the portion indicated by symbol B in FIG. 1) is
compared, and the speaker 3 is compared according to the comparison result. The correction of
lowering the gain of the variable gain circuit 404 is performed so that the output of the variable
gain circuit does not wrap around to the microphone 2 side, and the gain variable circuit 404 is
adjusted according to the noise environment detected by the noise environment detection
function of (4). Vehicle-side volume control function to change the gain to a preset value.
[0038]
(9)
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An echo environment detection function (can be used in combination with the function (4)
described above) to detect whether there is an environment in which echo components are less
likely to occur in the vehicle interior space, such as when the window of the vehicle is open.
(10)When it is detected by the echo environment detection function that the echo component is
not likely to be generated (for example, the window is opened), the volume of either or both of
the transmission signal and the reception signal is echoed. The function of controlling the
variable gain circuits 317 and 404 so that the volume is higher than the environment in which
components are likely to occur, for example, the volume when the window is closed. This is
because when the window is open, the amount of generated echo is small and the echo canceller
31 hardly works, so that the transmission volume and the reception volume are increased to
make it difficult for the howling to occur compared to the closed state.
[0039]
That is, the controller 50 causes the echo canceller 31 and the noise canceller 312 to echo in the
direction in which the signal quality of the transmission signal is improved in response to
deterioration of the noise environment which is the detection result in the noise environment
detection function of (4). It functions as a control means to control the gain of the transmission
signal in which one or both of the component and the noise component are canceled step by step
or continuously, and in the echo environment detection function, the vehicle interior space is an
echo component. When it is detected that the environment is hard to occur, the volume of either
or both of the transmission signal and the reception signal is gradually or continuously higher
than that in the environment where echo components are likely to occur. It also functions as
control means for controlling 317 and 404 so as to be large.
[0040]
A control flow performed by the controller 50 is shown in FIG. 2 as an example of this control.
As shown in FIG. 2, when the handsfree mode is turned on, the controller 50 detects an in-vehicle
noise environment (vehicle speed, air conditioner operating state, window opening / closing
state, etc.) (step S1), based on the detected environment. It is determined whether an echo is
likely to occur (step S2). As a result, if the controller 50 determines that the echo is likely to
occur, the controller 50 suppresses the echo component and the noise component according to
the detected noise environment (from YES route in step S2 to step S3), otherwise (If it is
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determined that echo is not likely to occur), the noise component corresponding to the detected
noise environment is suppressed (from the NO route of step S2 to step S4). For example, a
correction value corresponding to the environment is stored in a memory or the like, and
correction is performed based on the detection result. Further, since the echo is not likely to
occur, the output volume is corrected (increased) according to the noise environment (step S5).
[0041]
For example, according to the configuration and operation as described above and the control of
the controller 50 performed in the handsfree mode described above with reference to FIG. Can
be detected to automatically change the in-vehicle volume setting (increase the reception
volume).
[0042]
(b) Furthermore, it is possible to detect that the ceiling of the vehicle is open and to automatically
change the gain of the transmission signal that has passed the echo canceller 31 and the noise
canceller 312 in response to the driver's voice.
(c) Further, it is possible to automatically change the in-vehicle volume setting by detecting the
opening of the driver's seat side window.
[0043]
(d) Further, it is possible to automatically change the gain of the transmission signal that has
passed through the echo canceller 31 and the noise canceller 312 by detecting the driver's seat
side window open and receiving the driver's voice. (e) Furthermore, it is possible to automatically
change the in-vehicle volume setting by detecting the opening of the window on the passenger
seat side.
[0044]
(f) In addition, it is possible to automatically change the in-vehicle volume setting by detecting
the air volume of the air conditioner. (g) The air volume of the air conditioner is detected, and the
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driver's voice can be received to automatically change the gain of the transmission signal that
has passed through the echo canceller 31 and the noise canceller 312. (h) In addition, it is
possible to automatically change the in-vehicle volume setting by detecting the speed of the
vehicle.
[0045]
(i) Furthermore, the speed of the vehicle can be detected, and the voice of the driver can be
received to automatically change the gain of the transmission signal that has passed through the
echo canceller 31 and the noise canceller 312. As described above, according to the present
embodiment, when the noise level in the vehicle becomes large and the receiving volume is
raised, the voice of the other party 5 outside the vehicle can be clearly heard. When the voice
transmission volume is increased, the called party 5 can often hear the voice of the vehicle caller.
Furthermore, the transmission in which one or both of the echo component and the noise
component are canceled by the cancellation circuit in the direction in which the signal quality of
the transmission signal is improved as the noise in the vehicle increases and the noise
environment deteriorates. Since the gain of the signal is controlled, the voice of the driver can be
heard without a sense of incongruity, for example, noise can be reduced and echo can be reduced
on the side of the other party 5.
[0046]
In addition, since it is possible to adjust the transmission volume and the reception volume
appropriately according to the vehicle interior environment in consideration of the difference in
echo environment in the vehicle interior, it becomes easier to hear the voice of the other party.
[B] Others It is needless to say that the present invention is not limited to the embodiment
described above, and can be variously modified and implemented without departing from the
scope of the present invention.
[0047]
For example, it automatically detects the noise level of the road surface and automatically
changes the in-vehicle volume setting, or automatically changes the gain of the transmission
signal that has passed the echo canceller 31 and the noise canceler 312 in response to the
driver's voice. It is also possible to automatically change the echo cancellation setting condition
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for the transmission signal to the other party 5. In addition, it detects the voice of the person in
the rear seat and automatically changes the in-vehicle volume setting, receives the driver's voice,
and automatically adjusts the gain of the speech signal that has passed through the echo canceler
31 and the noise canceler 312. It is also possible to change the echo cancellation setting
condition for the transmission signal to the other party 5 or to change automatically.
[0048]
FIG. 1 is a block diagram showing an essential configuration of an on-vehicle hands-free talking
device as an embodiment of the present invention. It is a flowchart for demonstrating control by
the controller of the hands-free in-vehicle communication device shown in FIG.
Explanation of sign
[0049]
Reference Signs List 1 in-vehicle hands-free communication device 2 microphone 3 speaker 5
telephone of the other party 30 transmission processing unit 301 amplifier 302, 320 analog
filter 303 analog / digital converter (ADC) 304, 318 digital filter 305, 308, 311, 314, 317 gain
variable circuit 307, 313, 316 switch 312 noise canceller (noise cancel circuit) 315 slope filter
319 digital / analog converter (DAC) 31 echo canceller (echo cancel circuit) 306 adder 309 FIR
filter 310 howling / double talk detector 40 Reception processing unit 401, 409 Analog filter
402 Analog / digital converter (ADC) 403, 407 Digital filter 404 Variable gain Road (reception
volume adjusting circuit) 405 variable gain circuit 406 switches 408 digital / Analog Converter
(DAC) 50 controller (control means) 51 air conditioner 52 closing mechanism detecting circuit
53 vehicle speed sensor
15-04-2019
17
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