JP5874031B2 - Call signal processing device - Google Patents

Description

  The present invention relates to a call signal processing apparatus.

  Conventionally, an apartment intercom that transmits call voice between a dwelling unit installed in each dwelling unit, a common unit device (lobby interphone) installed in a common entrance, and a control room communication device installed in a control room A system is provided. In such an apartment intercom system, a communication device (such as a dwelling unit or a control room communication device) in the system and an external communication device (such as a fixed telephone or a mobile phone) connected to the public telephone network. Some have an external line transfer device (call signal processing device) for transferring voice between them (for example, see Patent Document 1). For example, if a control room call device is called from a dwelling unit while the manager is absent, the outside line transfer device transfers the call from the dwelling unit to the manager's mobile phone, and the outside line is transferred between the dwelling unit and the mobile phone. The transfer device transfers the call voice to each other. Thereby, the resident and the manager of the dwelling unit can talk using the dwelling unit and the mobile phone.

  By the way, the volume level of the voice transmitted from the external communication device varies greatly depending on the type (fixed telephone or mobile phone), manufacturer (manufacturer), or model of the external communication device. Therefore, an external line transfer device (call signal processing device) provided with a volume control unit that increases or decreases the volume level of the received signal is provided. FIG. 9 is a block diagram of a conventional external line transfer apparatus.

  This external line transfer apparatus includes a volume control unit 101, an A / D converter 102, a D / A converter 103, a two-wire / four-wire conversion unit 104, and a transmission unit 105. The transmission unit 105 is connected to a call device (such as a dwelling unit or a control room call device) via a signal line L, and performs packet transmission with the call signal processing device.

  The transmission unit 105 divides the reception signal (received voice data) output from the volume control unit 101 to create a packet, encodes the packet (voice packet), and converts the encoded bit string into an electrical signal. (Modulate) and send to signal line L. Further, the transmission unit 105 converts (modulates) an electric signal transmitted from the signal line L into a bit string, decodes a voice packet from the demodulated bit string, and decodes a transmitted signal (transmitted voice data). Is output to the D / A converter 103. Then, the transmission signal modulated into an analog signal by the D / A converter 103 is output to the 2-wire 4-wire conversion unit 104. The two-wire / four-wire conversion unit 104 is connected to the public telephone network by a local line (telephone line) Lx, sends a transmission signal to the telephone line Lx, and receives a reception signal transmitted through the telephone line Lx as A. / D converter 102 to output. The received signal is converted into a digital signal (received voice data) by the A / D converter 102 and input to the volume control unit 101.

  Then, the volume control unit 101 increases or decreases the volume level of the received signal so as to become a predetermined level, and outputs it to the transmission unit 105. Thereby, it is possible to suppress the variation in call voice.

Japanese Patent Laid-Open No. 2002-125059

  However, there is a case where an echo in which the transmitted signal goes around the received signal path is generated by the acoustic coupling between the speaker and the microphone of the external communication device. In this case, the echo component included in the received signal is also amplified by the volume control unit 101, and the voice level of the received signal cannot be adjusted to an optimal predetermined level, which may cause a reduction in call quality.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a call signal processing device that can suppress amplification of echoes by a volume control unit.

  The speech signal processing apparatus of the present invention includes a reception side signal path for transmitting a reception signal from a communication terminal, a transmission side signal path for transmitting a transmission signal to the communication terminal, and a signal level of the transmission side signal path. A first level calculation unit that calculates the gain, a gain according to the signal level of the received signal, a volume control unit that controls the signal level of the received signal by multiplying the received signal by the gain, and An operation control unit that controls the operation of the volume control unit, wherein the volume control unit updates the gain multiplied by the received signal, and the operation control unit is configured so that a calculation result of the first level calculation unit is When the threshold value is equal to or greater than 1, the updating of the gain by the volume control unit is stopped.

  The speech signal processing apparatus includes a second level calculation unit that calculates a signal level of the receiver signal path, and the operation control unit calculates the second level with respect to a calculation result of the first level calculation unit. When the ratio of the calculation results of the unit is equal to or greater than the second threshold, it is preferable that the gain control by the volume control unit is continued regardless of the calculation result of the first level calculation unit.

  The speech signal processing apparatus includes an echo canceller provided in a preceding stage of the second level calculation unit and configured to suppress an echo generated when the transmitted signal wraps around the receiver signal path due to acoustic coupling of the speech terminal. It is preferable.

  The speech signal processing apparatus includes an echo canceller provided at a subsequent stage of the second level calculation unit and configured to suppress an echo generated when the transmission signal wraps around the reception-side signal path due to acoustic coupling of the communication terminal. It is preferable.

  The speech signal processing apparatus includes a correlation value calculation unit that calculates a correlation value between the received signal and the transmission signal, and the operation control unit has a calculation result of the correlation value calculation unit equal to or less than a third threshold value. In some cases, it is preferable to continue updating the gain by the volume control unit regardless of the calculation result of the first level calculation unit.

  The speech signal processing apparatus includes a different code rate calculation unit that calculates a different code rate between the received signal and the transmission signal, and the operation control unit has a fourth calculation result of the different code rate calculation unit as a fourth result. When it is equal to or greater than the threshold value, it is preferable to continue the gain update by the volume control unit regardless of the calculation result of the first level calculation unit.

  In this call signal processing apparatus, an echo canceller that suppresses an echo generated when the transmitted signal wraps around the received signal path due to acoustic coupling of the call terminal, and the received signal path and the transmitted signal path A double-talk detection unit that detects a double-talk state in which a signal is transmitted at the same time, and the operation control unit calculates the first level calculation unit when the double-talk detection unit detects double-talk. Regardless of the result, it is preferable to continue updating the gain by the volume control unit.

  In this call signal processing apparatus, it is preferable that the second level calculation unit calculates a signal level from an average of absolute values of the received signal.

  In this call signal processing device, it is preferable that the first level calculation unit calculates a signal level from an average of absolute values of the transmission signals.

  As described above, the present invention has an effect that the amplification of echoes by the volume control unit can be suppressed.

It is a block diagram which shows the structure of the external line transfer apparatus of Embodiment 1 of this invention. It is a system block diagram of the intercom system for apartment houses containing the external line transfer apparatus same as the above. It is a block diagram which shows the structure of the external line transfer apparatus of Embodiment 2. It is a block diagram which shows another structure same as the above. It is a block diagram which shows another structure same as the above. It is a block diagram which shows the structure of the external line transfer apparatus of Embodiment 3. It is a block diagram which shows the structure of the external line transfer apparatus of Embodiment 4. FIG. 10 is a block diagram illustrating a configuration of an external line transfer device according to a fifth embodiment. It is a block diagram which shows the structure of the conventional external line transfer apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 2 shows a system configuration example of an intercom system for apartment houses including the external line transfer device E of the present embodiment (corresponding to the call signal processing device of the present invention). This intercom system for collective housing is composed of a plurality of units (only one in the figure) dwelling unit communication device A installed in each dwelling unit of the condominium and a common unit communication device (not shown) installed in the common entrance of the collective housing. , Main line control device B, management room communication device C, and the like.

  Each dwelling unit communication device A is branched and connected to the trunk line L1 via the dwelling unit separate line L2 and the branching unit D. The trunk line L1 is connected to the trunk line control device B, and a plurality (only one in the figure) of branching devices D are provided on the trunk line L1. Further, a management room call device C is connected to the main line control device B via a signal line L3. The management room call device C is installed in the management room of the apartment house, and is used when the manager calls the resident of each dwelling unit.

  In the intercom system for apartment houses in this embodiment, digitally modulated audio information (audio data), video information (video data), and control information (control data) are transmitted through transmission lines (main line L1, dwelling line L2, signal line L3). , L4). For example, in a common area communication device (lobby intercom), when a visitor accepts an operation input of a dwelling unit number of any dwelling unit by operating a numeric keypad or a touch panel, a packet storing the dwelling unit number in a data field and imaging A packet in which a video (video data) of a visitor imaged by the apparatus is stored in a data field is transmitted (packet transmission) to the address of the trunk control apparatus B via a signal line. The main line control device B sends a control packet storing a call command for notifying a call from the lobby intercom in the data field and a video packet storing the video data in the data field to the main line L1. When the control unit and the video packet are received via the trunk line L1 and the unit-specific line L2, the unit communication device A installed in the unit with the unit number receives a call command (control signal) stored in the data field of the control packet. ) To ring from the speaker. Further, the video data stored in the data field of the video packet is processed to display the video of the visitor on a display device such as a liquid crystal display. When a resident who has heard the ringing tone operates a response button (not shown) of the dwelling unit communication apparatus A, a voice signal (sending signal) output from the microphone is packet-transmitted via the dwelling unit separate line L2. Similarly, also in the lobby intercom, a voice signal (transmission signal) output from the microphone is packet-transmitted to the dwelling unit communication device A via the trunk line control device B. As a result, a resident of the dwelling unit and a visitor can make an interphone call using the dwelling unit call device A and the lobby intercom.

  In addition, the management room call device C can be called from the dwelling unit call device A, and the resident and the manager can talk using the dwelling unit call device A and the control room call device C. In this case, a packet including control data for calling the control room call device C from the dwelling unit call device A is transmitted, and the packet is transmitted to the control room call device C via the trunk line control device B. When the handset of the control room call device C is off-hook (or the call button is operated), voice data is transferred between the dwelling unit call device A and the control room call device C as in the case of the lobby intercom. Packets are transmitted to each other. However, since the dwelling unit call device A, the main line control device B, the lobby intercom, and the management room call device C described above can be realized by using a conventionally known technique, detailed illustration and description of the configuration are omitted.

  Here, when a call is made from the dwelling unit call device A to the control room call device C while the manager is absent, the call of the dwelling unit call device A is transferred to the mobile phone possessed by the manager or the reception center of the management company. . Then, it is desirable to be able to talk by transmitting voice between a call terminal such as a transfer destination mobile phone or a reception center phone (hereinafter referred to as an external call device F) and the dwelling unit call device A. . For this purpose, the intercom system for collective housing in this embodiment includes an external line transfer device E that transfers audio between the dwelling unit call device A and the external call device F.

  As shown in FIG. 1, the external line transfer device E includes a volume control unit 1, an operation control unit 2, a first level calculation unit 3, an A / D converter 4, a D / A converter 5, and 2 A line-to-line conversion unit 6 and a transmission unit 7 are provided. The transmission unit 7 is connected to the trunk line control device B via the signal line L4, and performs packet transmission with the dwelling unit call device A via the trunk line control device B.

  The transmission unit 7 divides the reception signal (received voice data) output from the volume control unit 1 to create a packet, encodes the packet (voice packet), and converts the encoded bit string into an electrical signal. (Modulate) and send to signal line L4. The transmission unit 7 converts (modulates) the electric signal transmitted from the signal line L4 into a bit string, and transmits a transmission signal (transmission voice data) obtained by decoding a voice packet from the demodulated bit string. The signal is output to the D / A converter 5 via a path (lower signal path in FIG. 1). Then, the transmission signal modulated into an analog signal by the D / A converter 5 is output to the 2-wire 4-wire converter 6. The two-wire / four-wire conversion unit 6 is connected to the public telephone network N by a station line (telephone line) Lx, and transmits a transmission signal to the telephone line Lx and also receives a reception signal transmitted through the telephone line Lx. Output to the A / D converter 4. The received signal is converted into a digital signal (received voice data) by the A / D converter 4 and input to the volume control unit 1 via the received signal path (upper signal path in FIG. 1).

  The volume control unit 1 increases / decreases the signal level (voice level) of the received reception signal to a predetermined level and outputs the signal level to the transmission unit 7. Specifically, the volume control unit 1 calculates a gain according to the signal level of the input received signal, and multiplies the received signal by the calculated gain to change the signal level of the received signal to a predetermined level for transmission. Output to unit 7. Further, the volume control unit 1 updates the gain multiplied by the received signal in order to control it to a predetermined level even when the signal level of the received received signal varies.

  The first level calculation unit 3 calculates the voice level (signal level) of the transmission signal (transmission voice data). Then, the first level calculation unit 3 outputs the calculation result of the signal level of the transmission signal to the operation control unit 2. Specifically, the first level calculation unit 3 calculates the average value (short-term average value) of the absolute value of the transmission signal in a relatively short time, and outputs it to the operation control unit 2.

  In general, it is considered that the level of the short-time average value is determined mainly by the voice component included in the input signal (speech signal). On the other hand, the average value (long-term average value) of the input signal over a relatively long time is determined mainly by the noise component (sound component other than voice) contained in the input signal (speech signal). It is considered.

  Therefore, the first level calculation unit 3 performs arithmetic processing of the following formula (1) or formula (2) in order to calculate the level of the voice component included in the transmission signal, and calculates the absolute value of the transmission signal. A short-time average value L (n) is calculated. It is assumed that the absolute value of the transmission signal is x (n) and the average number of samples is M.

  Then, the first level calculation unit 3 outputs the calculated short-term average value L (n) of the absolute value of the transmission signal to the operation control unit 2 as a signal level calculation result of the transmission signal. As described above, the first level calculation unit 3 can calculate the signal level of the transmission signal by a simple calculation.

  The operation control unit 2 controls the operation of the volume control unit 1, specifically, execution / stop of gain update by the volume control unit 1. The operation control unit 2 of the present embodiment determines execution (continuation) or stop of gain update by the volume control unit 1 based on the calculation result of the first level calculation unit 3. Specifically, a first threshold value is set in advance in the operation control unit 2, and the first threshold value is compared with the calculation result of the first level calculation unit 3.

  When the calculation result of the first level calculation unit 3 is less than the first threshold value, the operation control unit 2 has a low signal level of the transmission signal and is acoustically coupled to the external call device F (the other party's call terminal). It is determined that there is no or small echo that the transmitted signal has entered the receiver signal path. Therefore, when the calculation result of the first level calculation unit 3 is less than the first threshold, the operation control unit 2 continues the gain update by the volume control unit 1. As a result, the signal level of the received signal is adjusted to a predetermined level, and variations in received sound volume can be suppressed.

  On the other hand, when the calculation result of the first level calculation unit 3 is equal to or higher than the first threshold, the operation control unit 2 has a high signal level of the transmission signal, and the sound of the external call device F (the other party's call terminal) It is determined that an echo is generated in which the transmission signal has entered the receiver signal path due to the combination. Therefore, when the calculation result of the first level calculation unit 3 is equal to or greater than the first threshold, the operation control unit 2 stops the gain update by the volume control unit 1.

  As described above, in the present embodiment, the volume control unit 1 stops updating the gain even when the signal level of the transmission signal is high and an echo occurs in which the transmission signal wraps around the reception-side signal path. Therefore, amplification of the echo component is suppressed, and a comfortable call environment can be provided.

  In the present embodiment, the call signal processing device of the present invention is applied to the external line transfer device E of the intercom system for collective housing, but the present invention is not limited to this. For example, the call signal processing device of the present invention may be applied to a call device (call terminal) such as an interphone master / slave device or telephone.

(Embodiment 2)
FIG. 3 shows a block configuration diagram of the external line transfer apparatus E of the present embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to Embodiment 1, and description is abbreviate | omitted.

  The external line transfer apparatus E according to the present embodiment is characterized in that the second level calculation unit 8 that calculates the signal level of the received signal is provided for the configuration of the first embodiment.

  The second level calculation unit 8 calculates the signal level of the received signal and outputs the calculation result to the operation control unit 2. The second level calculation unit 8 has the same configuration as that of the first level calculation unit 3, and calculates the short-time average value of the absolute value of the received signal (see equations (1) and (2)). . Then, the second level calculation unit 8 outputs the calculated short-term average value of the absolute value of the received signal to the operation control unit 2 as a signal level calculation result of the received signal.

  Then, the operation control unit 2 executes (continues) the gain update by the volume control unit 1 based on both the calculation result of the first level calculation unit 3 and the calculation result of the second level calculation unit 8.・ Determine to stop. As in the first embodiment, the operation control unit 2 compares the calculation result of the first level calculation unit 3 with the first threshold value, and the calculation result of the first level calculation unit 3 is the first threshold value. In the case above, the update of the gain by the volume control unit 1 is stopped.

  In the present embodiment, when the ratio of the calculation result of the second level calculation unit 8 to the calculation result of the first level calculation unit 3 is equal to or greater than the second threshold, the calculation result of the first level calculation unit 3 Regardless, the volume control unit 1 continues to update the gain. That is, even if the calculation result of the first level calculation unit 3 is greater than or equal to the first threshold, (calculation result of the second level calculation 8) / (calculation result of the first level calculation unit 3) ≧ second In the case of the threshold value, the operation control unit 2 continues to update the gain by the volume control unit 1. In this case, the operation control unit 2 determines that the received signal is sufficiently larger than the transmitted signal, and that the voice of the speaker using the external communication device F is included in the received signal. Therefore, when the calculation result of the second level calculation unit 8 with respect to the calculation result of the first level calculation unit 3 is equal to or greater than the second threshold, the operation control unit 2 continues to update the gain by the volume control unit 1. . As a result, the signal level of the received signal including the voice of the speaker using the external call device F is adjusted to a predetermined level, and variations in the received sound volume can be suppressed.

  Thus, in this embodiment, even when the signal level of the transmission signal is high, when it is determined that the voice of the speaker who uses the external call device F is included in the reception signal, By continuing to update the gain by the volume control unit 1, it is possible to improve the call environment.

  4 and 5, an echo canceller 9 that suppresses echoes caused by acoustic coupling of the external communication device F may be provided.

  The echo canceller 9 has a conventionally known configuration including an adaptive filter and a subtracter (not shown), and adaptively identifies the impulse response of the feedback path formed by the acoustic coupling of the external communication device F by the adaptive filter. Then, the echo component estimated from the transmission signal input to the D / A converter 5 is subtracted from the reception signal output from the A / D converter 4 by the subtractor to suppress the echo.

  By providing such an echo canceller 9, even if the signal level of the transmission signal is high, the received signal with the echo suppressed is input to the volume control unit 1. Amplification can be suppressed.

  In addition, as shown in FIG. 4, by providing the echo canceller 9 before the second level calculation unit 8, the second level calculation unit 8 allows the signal level of the received signal whose echo is suppressed by the echo canceller 9. Can be calculated. Thereby, the detection accuracy of whether or not the voice of the speaker who uses the external call device F is included in the received signal can be improved.

  However, when the echo canceller 9 is provided upstream of the second level calculation unit 8, the second threshold value to be compared with the ratio of the calculation result of the second level calculation unit 8 to the calculation result of the first level calculation unit 3 is set. It is necessary to set in consideration of the convergence state of the adaptive filter. Therefore, as shown in FIG. 5, by providing an echo canceller 9 subsequent to the second level calculation unit 8, the second threshold can be set regardless of the convergence state of the adaptive filter.

(Embodiment 3)
FIG. 6 shows a block configuration diagram of the external line transfer apparatus E of the present embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to Embodiment 1, and description is abbreviate | omitted.

  The external line transfer apparatus E according to the present embodiment is characterized in that the correlation value calculation unit 10 is included in the configuration of the first embodiment. Correlation value calculation unit 10 detects a reception signal and a transmission signal, calculates a correlation value between the reception signal and the transmission signal, and outputs the correlation value to operation control unit 2.

  Based on the calculation result of the first level calculation unit 3 and the calculation result of the correlation value calculation unit 10, the operation control unit 2 determines execution (continuation) / stop of gain update by the volume control unit 1. As in the first embodiment, the operation control unit 2 compares the calculation result of the first level calculation unit 3 with the first threshold value, and the calculation result of the first level calculation unit 3 is the first threshold value. In the case above, the update of the gain by the volume control unit 1 is stopped.

  In the present embodiment, when the calculation result of the correlation value calculation unit 10 is equal to or less than the third threshold value, the operation control unit 2 uses the volume control unit 1 regardless of the calculation result of the first level calculation unit 3. Continue to update the gain. That is, even when the calculation result of the first level calculation unit 3 is equal to or greater than the first threshold value, when the calculation result of the correlation value calculation unit 10 is equal to or less than the third threshold value, the operation control unit 2 The gain update by 1 is continued. In this case, the operation control unit 2 determines that there is no echo or a small echo by the external call device F, and that the received signal is dominated by the voice of the speaker using the external call device F. Therefore, when the calculation result of the correlation value calculation unit 10 is equal to or less than the third threshold, the operation control unit 2 continues to update the gain by the volume control unit 1 regardless of the calculation result of the first level calculation unit 3. Let As a result, the signal level of the received signal including the voice of the speaker using the external call device F is adjusted to a predetermined level, and variations in the received sound volume can be suppressed.

  On the other hand, when the calculation result of the correlation value calculation unit 10 is larger than the third threshold value, the operation control unit 2 determines that the echo signal from the external communication device F is included in the received signal, and the volume control unit 1 By stopping the gain update, the amplification of the echo component is suppressed.

  As described above, in this embodiment, even when the signal level of the transmission signal is high, when it is determined that the voice of the speaker who uses the external call device F is included in the reception signal, The telephone call environment can be improved by continuing the gain update by the volume control unit 1.

(Embodiment 4)
FIG. 7 shows a block diagram of the external line transfer apparatus E of the present embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to Embodiment 1, and description is abbreviate | omitted.

  The external line transfer apparatus E of the present embodiment is characterized in that it includes the different code rate calculation unit 11 with respect to the configuration of the first embodiment. The different code rate calculation unit 11 detects the received signal and the transmitted signal, calculates the different code rate between the received signal and the transmitted signal (the rate at which the codes of the transmitted signal and the received signal are different), and controls the operation. Output to part 2.

  Based on the calculation result of the first level calculation unit 3 and the calculation result of the different code rate calculation unit 11, the operation control unit 2 determines execution (continuation) / stop of gain update by the volume control unit 1. As in the first embodiment, the operation control unit 2 compares the calculation result of the first level calculation unit 3 with the first threshold value, and the calculation result of the first level calculation unit 3 is the first threshold value. In the case above, the update of the gain by the volume control unit 1 is stopped.

  In the present embodiment, when the calculation result of the different code rate calculation unit 11 is equal to or greater than the fourth threshold value, the operation control unit 2 does not depend on the calculation result of the first level calculation unit 3, but the volume control unit 1. Continue to update the gain. That is, even if the calculation result of the first level calculation unit 3 is equal to or greater than the first threshold value, the operation control unit 2 performs the volume control when the calculation result of the different code rate calculation unit 11 is equal to or greater than the fourth threshold value. The gain update by the unit 1 is continued. In this case, the operation control unit 2 determines that there is no echo or a small echo by the external call device F, and that the received signal is dominated by the voice of the speaker using the external call device F. Therefore, when the calculation result of the different code rate calculation unit 11 is equal to or greater than the fourth threshold, the operation control unit 2 updates the gain by the volume control unit 1 regardless of the calculation result of the first level calculation unit 3. Let it continue. As a result, the signal level of the received signal including the voice of the speaker using the external call device F is adjusted to a predetermined level, and variations in the received sound volume can be suppressed.

  On the other hand, when the calculation result of the different code rate calculation unit 11 is less than the fourth threshold, the operation control unit 2 determines that the echo signal from the external communication device F is included in the received signal, and the volume control unit 1 The amplification of the echo component is suppressed by stopping the update of the gain by.

  As described above, in this embodiment, even when the signal level of the transmission signal is high, when it is determined that the voice of the speaker who uses the external call device F is included in the reception signal, The telephone call environment can be improved by continuing the gain update by the volume control unit 1.

(Embodiment 5)
FIG. 8 shows a block diagram of the external line transfer apparatus E of the present embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to Embodiment 1, and description is abbreviate | omitted.

  The external line transfer apparatus E according to the present embodiment is characterized in that an echo canceller 9 having a double-talk detection unit 91 is provided for the configuration of the first embodiment.

  The echo canceller 9 has a conventionally known configuration including an adaptive filter and a subtracter (not shown), and adaptively identifies the impulse response of the feedback path formed by the acoustic coupling of the external communication device F by the adaptive filter. Then, the echo component estimated from the transmission signal input to the D / A converter 5 is subtracted from the reception signal output from the A / D converter 4 by the subtractor to suppress the echo.

  By providing such an echo canceller 9, even if the signal level of the transmission signal is high, the received signal with the echo suppressed is input to the volume control unit 1. Amplification can be suppressed.

  The echo canceller 9 has a double talk detector 91. The double talk detector 91 detects a double talk state in which signals are simultaneously transmitted to the reception side signal path and the transmission side signal path. Then, the double talk detector 91 outputs the detection result to the operation controller 2.

  Based on the calculation result of the first level calculation unit 3 and the detection result of the double talk detection unit 91, the operation control unit 2 determines whether to execute (continue) or stop the gain update by the volume control unit 1. As in the first embodiment, the operation control unit 2 compares the calculation result of the first level calculation unit 3 with the first threshold value, and the calculation result of the first level calculation unit 3 is the first threshold value. In the case above, the update of the gain by the volume control unit 1 is stopped.

  In the present embodiment, the operation control unit 2 updates the gain by the volume control unit 1 regardless of the calculation result of the first level calculation unit 3 when the double talk detection unit 91 detects double talk. To continue. That is, even when the calculation result of the first level calculation unit 3 is equal to or greater than the first threshold value, the operation control unit 2 determines the gain by the volume control unit 1 when the double talk detection unit 91 detects double talk. Keep updating. In this case, the operation control unit 2 determines that the echo from the external communication device F is suppressed by the echo canceller 9 and that the echo contained in the received signal input to the volume control unit 1 is absent or small. Therefore, when the double talk detecting unit 91 detects double talk, the operation control unit 2 continues the gain update by the volume control unit 1 regardless of the calculation result of the first level calculation unit 3. As a result, the signal level of the received signal including the voice of the speaker using the external call device F is adjusted to a predetermined level, and variations in the received sound volume can be suppressed.

  As described above, in this embodiment, even if the signal level of the transmission signal is high, echo is suppressed, so that the call environment is improved by continuing the gain update by the volume control unit 1. Can do.

  In the present embodiment, the echo canceller 9 and the double talk detector 91 are integrally configured, but the echo canceller 9 and the double talk detector 91 may be configured separately.

DESCRIPTION OF SYMBOLS 1 Volume control part 2 Operation | movement control part 3 1st level calculation part 4 A / D converter 5 D / A converter 6 2 line | wire 4 line conversion part 7 Transmission part

Claims (9)

A receiver signal path for transmitting a reception signal from a call terminal;
A transmission side signal path for transmitting a transmission signal to the call terminal;
A first level calculation unit for calculating a signal level of the transmission side signal path;
A volume control unit that calculates a gain according to the signal level of the received signal, and controls the signal level of the received signal by multiplying the received signal by the gain;
An operation control unit for controlling the operation of the volume control unit,
The volume control unit updates the gain multiplied by the reception signal,
The operation control unit stops the update of the gain by the volume control unit when the calculation result of the first level calculation unit is equal to or greater than a first threshold value. A second level calculator for calculating a signal level of the receiver signal path,
When the ratio of the calculation result of the second level calculation unit to the calculation result of the first level calculation unit is equal to or greater than a second threshold, the operation control unit determines that the calculation result of the first level calculation unit is 2. The call signal processing apparatus according to claim 1, wherein, regardless of the volume control unit, the gain is continuously updated by the volume control unit.   The echo canceller is provided in a preceding stage of the second level calculation unit and suppresses an echo generated when the transmission signal wraps around the signal path on the receiving side due to acoustic coupling of the call terminal. 3. The call signal processing device according to 2.   The echo canceller is provided at a subsequent stage of the second level calculation unit and suppresses an echo generated when the transmission signal wraps around the signal path on the receiving side due to acoustic coupling of the call terminal. 3. The call signal processing device according to 2. A correlation value calculation unit for calculating a correlation value between the received signal and the transmitted signal;
When the calculation result of the correlation value calculation unit is equal to or less than a third threshold, the operation control unit continues to update the gain by the volume control unit regardless of the calculation result of the first level calculation unit. The speech signal processing apparatus according to claim 1. A different code rate calculation unit for calculating a different code rate between the received signal and the transmitted signal;
When the calculation result of the different code rate calculation unit is equal to or greater than a fourth threshold, the operation control unit continues to update the gain by the volume control unit regardless of the calculation result of the first level calculation unit The call signal processing apparatus according to claim 1, wherein: An echo canceller that suppresses echoes that occur when the transmitted signal wraps around the receiver signal path due to acoustic coupling of the call terminal;
A double-talk detector that detects a double-talk state in which signals are transmitted simultaneously to the receiver-side signal path and the transmitter-side signal path;
The operation control unit, when the double talk detection unit detects double talk, continues the gain update by the volume control unit regardless of the calculation result of the first level calculation unit. The call signal processing apparatus according to claim 1.   5. The call signal processing apparatus according to claim 2, wherein the second level calculation unit calculates a signal level from an average of absolute values of the reception signals. 6.   9. The call signal processing apparatus according to claim 1, wherein the first level calculation unit calculates a signal level from an average of absolute values of the transmission signals.

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