JP2018049124A - Radio communication device, radio communication system, and noise reduction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the generation of undesired sound (noise) readily with a light load.SOLUTION: Radio communication devices 10A and 10B for communicating with each other by voice using radio communication each include: a communication unit 11 for receiving voice data transmitted by a transmission side device; a detection unit 13 for detecting, as a change point, a point where voice data received by the communication unit 11 changes from a non-silent state to a silent state or a point where the voice data changes from a silent state to a non-silent state; a deletion unit 14 for deleting a waveform including the change point detected by the detection unit from the voice data; and a reproduction unit 15 for reproducing the voice data after the deletion unit 14 deleted the waveform.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication apparatus, a wireless communication system, and a noise reduction method for performing a voice call using wireless communication.

  As a communication system for performing a voice call, a communication system using a network such as the Internet or a LAN is widely used. In such a communication system, the voice data is converted into a digital signal by being encoded in the communication terminal on the transmission side, and is transmitted to the network in the state of individual divided packets. When the packet reaches the receiving communication terminal via the network, it is combined and decoded at the receiving communication terminal to be converted into an analog audio signal (audio data). Then, the audio signal is reproduced at the receiving communication terminal.

  In such a communication system, packet transmission delay and packet loss may occur in the network. When packet transmission delay or packet loss occurs, some of the packets do not reach the receiving communication terminal, and the value of the voice data suddenly becomes silent (value 0). In this way, when the value of the voice data fluctuates rapidly, for example, noise such as “buzz” (an abnormal sound different from the call sound) may occur. The generation of such noise may give an unpleasant sound to the receiver and may cause trouble in the call. Therefore, a process of interpolating the shortage of audio data is performed in the communication terminal, thereby correcting the elapsed time (see, for example, Patent Document 1).

  In recent years, with the rapid spread of small mobile terminals, with the increase of voice calls by wireless communication using small mobile terminals, the demand for higher sound quality in voice calls by such wireless communication has also increased.

JP 2007-114417 A

  As shown in the above-mentioned Patent Document 1, when a sudden change in the value of audio data is detected in the communication terminal on the receiving side, sound quality improvement processing is performed such that the audio data is smoothed and corrected to an appropriate value. When executed, the communication terminal on the receiving side requires a relatively high computing capability, and it is also necessary to install and operate a floating point arithmetic unit and a digital signal processor. For this reason, the above-described sound quality improvement process causes an increase in cost, and it is difficult to execute the above process when a device having a relatively low calculation capability such as a wireless communication device is used as a communication terminal on the receiving side. It has the problem of being.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a radio communication device, a radio communication system, and a noise reduction method capable of reducing noise generation easily and with low load. To do.

  In order to achieve the above object, according to the present invention, a wireless communication device for performing a voice call using wireless communication, which is received by a communication unit that receives voice data transmitted from a transmission-side device, and the communication unit. A detection unit that detects a point at which the voice data changes from the silent state to the silent state or a point at which the silent state changes to the silent state, and a waveform including the change point detected by the detection unit from the voice data Provided is a wireless communication device comprising: an erasing unit for erasing; and a reproducing unit for reproducing audio data whose waveform has been erased by the erasing unit.

  Further, in the present invention, when the audio data changes from the silent state to the silent state, the detection unit has a constant difference between the value of the nearest non-silent state and the silent state value that changes to the silent state in the voice data. When the audio data changes from the silent state to the silent state, the difference between the value immediately after the voice data changes to the silent state and the silent state value is a certain value or more. If it is determined whether or not there is a certain value or more, a point where the silent state is changed to the silent state or a point where the silent state is changed to the silent state is detected as the changing point. The waveform from the point where the value of the audio data before the point is 0 to the change point or the waveform from the change point to the point where the value of the audio data after the change point is 0 is deleted from the audio data. It may be configured.

  In the present invention, the communication unit may be configured to perform wireless communication using BLE.

  In the present invention, the detection unit may be configured to recognize that the audio data is in a silent state when the value of the audio data is 0 for a certain period.

  In addition, the present invention includes the above-described wireless communication device, and a gateway that is connected to the communication network and transmits / receives voice data to / from the wireless communication device and performs protocol conversion of the voice data. A wireless communication system is provided.

  According to the present invention, there is also provided a noise reduction method for a wireless communication device that performs a voice call using wireless communication, the communication step for receiving voice data transmitted from a transmission-side device, and the voice received in the communication step. A detection step for detecting a point at which data changes from a silent state to a silent state or a point at which the silent state changes to a silent state as a change point, and a waveform including the change point detected at the detection step is deleted from the audio data. There is provided a noise reduction method comprising: an erasing step; and a reproducing step of reproducing audio data whose waveform has been erased in the erasing step.

  Further, in the present invention, the detection step is such that when the audio data changes from the silent state to the silent state, the difference between the nearest non-silent state value and the silent state value that changes to the silent state in the voice data is constant. When the audio data changes from the silent state to the silent state, the difference between the value immediately after the voice data changes to the silent state and the silent state value is a certain value or more. If it is determined whether or not there is a certain value or more, a point that changes from a silent state to a silent state or a point that changes from a silent state to a silent state is detected as a changing point, and the erasure step changes The waveform from the point where the value of the audio data before the point is 0 to the change point or the waveform from the change point to the point where the value of the audio data after the change point is 0 is deleted from the audio data. It may be configured.

  Moreover, in this invention, the structure which performs radio | wireless communication using BLE in a communication step may be sufficient.

  Further, the present invention may be configured such that the voice data is recognized as being silent when the voice data value of 0 continues for a certain period.

  ADVANTAGE OF THE INVENTION According to this invention, in the voice call by radio | wireless communication, noise can be reduced easily and with low load.

It is a block diagram which shows an example of a structure of the radio | wireless communications system which concerns on embodiment. It is a block diagram which shows an example of the radio | wireless communication apparatus of FIG. It is a figure which shows an example of an audio | voice waveform, (a) is a figure which shows an example of a normal audio | voice waveform, (b) is a figure which shows an example of the audio | voice waveform in which the defect | deletion produced. 3 is a flowchart illustrating an example of processing related to audio reproduction performed by the wireless communication apparatus of FIG. 2. It is a figure which shows an example of the audio | voice waveform after correction | amendment, (a) is a figure which shows the correction | amendment part A and B in an audio | voice waveform, (b) is the figure which expanded the correction | amendment part A of (a), (c) is ( It is the figure which expanded the correction | amendment part B of a).

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to this. In the drawings, in order to describe the embodiment, the scale may be changed as appropriate, for example, by partially enlarging or emphasizing.

  FIG. 1 is a block diagram illustrating an example of a configuration of a wireless communication system SYS according to the embodiment. The wireless communication system SYS is a data communication system using a wireless technology such as Bluetooth (registered trademark), which is one of short-range wireless communication standards for digital devices. As shown in FIG. 1, the wireless communication system SYS includes wireless communication devices 10 </ b> A and 10 </ b> B and a gateway 20. In the wireless communication system SYS shown in FIG. 1, two wireless communication devices 10A and 10B are shown, but three or more wireless communication devices may be provided. Further, in the wireless communication system SYS shown in FIG. 1, only one gateway 20 is shown, but two or more gateways may be provided.

  The wireless communication devices 10A and 10B are devices that perform a voice call using a wireless technology such as Bluetooth (registered trademark). In the present embodiment, the wireless communication devices 10A and 10B can perform a voice call using wireless communication. Further, the wireless communication devices 10A and 10B perform wireless communication with the gateway 20, respectively, so that other communication devices 41 and 42 (wireless communication devices having the same configuration as the wireless communication devices 10A and 10B) are connected via the communication network 30. Voice calls).

  The wireless communication devices 10A and 10B are assumed to be low power consumption devices such as a Bluetooth (registered trademark) receiver with a low calculation capability. BLE (Bluetooth (Registered Trademark) Low Energy), that is, a voice call based on Bluetooth (Registered Trademark) Version 4.0, which is a low-power-consumption wireless technology, is being announced, and voice conversation by a device with low computing power is being realized is there. In addition, the Bluetooth (registered trademark) version 5 standard was established. This Bluetooth (registered trademark) version 5 corresponds to Bluetooth (registered trademark) version 4. Compared with x, the transmission capability has been strengthened to double the speed, 4 times the distance, and 8 times the amount of data, and the communication by broadcast has been standardized. (Registered trademark) is being adopted. Therefore, with the advent of Bluetooth (registered trademark) version 5, it is expected that Bluetooth (registered trademark) will be adopted in the field of voice calls. However, as described above, it has been difficult to implement the conventional sound quality improvement processing in a device with low calculation capability. Therefore, the present invention proposes the following noise reduction measures.

  The gateway 20 is a device that connects networks of different protocols by performing protocol conversion of data. The gateway 20 is connected to the communication network 30. The gateway 20 is configured to be capable of wireless communication with the wireless communication devices 10A and 10B. When the gateway 20 receives the voice data packet transmitted from the wireless communication devices 10A and 10B, the gateway 20 performs protocol conversion on the received voice data packet. The gateway 20 transmits data generated by protocol conversion to the other communication devices 41 and 42 via the communication network 30. When the gateway 20 receives the voice data packets transmitted from the other communication devices 41 and 42 via the communication network 30, the gateway 20 converts the received voice data packets into a protocol. Then, the gateway 20 transmits the data generated by the protocol conversion to the wireless communication device (for example, one of the wireless communication devices 10A and 10B) by wireless communication.

  The communication network 30 connects communication devices such as the wireless communication devices 10A and 10B so that they can communicate with each other. Examples of the communication network 30 include the Internet and a LAN (Local Area Network). The communication network 30 may be a wired network or a wireless network. Voice over Internet Protocol (VoIP) refers to a technology that encodes and compresses voice using various encoding methods and converts it into packets and transmits it in real time over an IP (Internet Protocol) network.

  FIG. 2 is a block diagram illustrating an example of the wireless communication devices 10A and 10B in the wireless communication system SYS. As illustrated in FIG. 2, the wireless communication devices 10 </ b> A and 10 </ b> B include a communication unit 11, an encoding / decoding unit 12, a detection unit 13, an erasing unit 14, and a reproduction unit 15. Although not shown in FIG. 2, the wireless communication devices 10A and 10B are also provided with an antenna, a microphone, a speaker, and the like. In addition, it is assumed that the wireless communication device 10A and the wireless communication device 10B have the same configuration.

  The communication unit 11 transmits and receives audio data by wireless communication between the wireless communication device and the gateway 20. In the present embodiment, the communication unit 11 performs wireless communication using BLE (or a wireless communication standard of Bluetooth (registered trademark) version 4.x or higher).

  The encoding / decoding unit 12 encodes an audio signal emitted by a user of the wireless communication devices 10A and 10B and converts the audio signal into digital signal audio data. The encoding / decoding unit 12 decodes the audio data received by the communication unit 11.

  The detection unit 13 detects a point at which the audio data decoded by the encoding / decoding unit 12 changes from a silent state to a silent state or a point at which the voice data changes from a silent state to a silent state. Here, the silent state is a state in which there is no sound, and specifically means a state in which the value 0 of the audio data continues for a certain period. Further, the non-silent state is a state where there is sound, specifically, a state where the value of the audio data is not zero. In the present embodiment, the detection unit 13 detects a portion where audio data is lost due to a transmission delay or packet loss of audio data packets.

  The erasure unit 14 erases the waveform including the change point detected by the detection unit 13 from the audio data. This reduces the occurrence of noise (abnormal noise) such as “buzz”. The reproduction unit 15 reproduces audio data (that is, outputs audio from a speaker). When the waveform is erased by the erasing unit 14, the reproducing unit 15 reproduces the audio data from which the waveform is erased by the erasing unit 14.

  Next, a detailed process of audio data processing in the wireless communication devices 10A and 10B will be described with reference to the drawings. First, a speech waveform will be described based on packet transmission delay, packet loss, and the like. FIG. 3 is a diagram illustrating an example of a speech waveform, where (a) is a diagram illustrating an example of a normal speech waveform, and (b) is a diagram illustrating an example of a speech waveform in which a defect has occurred. 3A and 3B, the vertical axis indicates volume and the horizontal axis indicates time, and the sound intensity (sound pressure) is expressed as the amplitude of the speech waveform. The waveforms shown in FIGS. 3A and 3B are speech waveforms when the amplitude value is represented by 16 bits at a sampling frequency of 8 kHz in PCM (pulse code modulation).

  A normal speech waveform has a continuous wave shape as shown in FIG. By the way, when some packets do not reach due to packet transmission delay, packet loss, or the like, as shown in FIG. When a part of the voice waveform is lost, noise (abnormal noise) such as “buzz” is generated due to a sudden change in sound pressure. The abnormal sound generators 1 and 2 shown in FIG. 3B are the places where noise (abnormal noise) is generated. Therefore, in the audio data processing in the wireless communication devices 10A and 10B, the following processing is performed.

  FIG. 4 is a flowchart illustrating an example of a sound reproduction process performed by the wireless communication devices 10A and 10B. FIG. 5 is a diagram showing an example of a corrected speech waveform, (a) is a diagram showing correction parts A and B in the speech waveform, and FIG. 5 (b) is a diagram of FIG. 5 (a). FIG. 5C is an enlarged view of the part A, and FIG. 5C is an enlarged view of the correction part B in FIG. The waveforms shown in FIGS. 3A and 3B are also audio waveforms when the amplitude value is represented by 16 bits at a sampling frequency of 8 kHz in PCM (pulse code modulation).

  As shown in FIG. 4, in the wireless communication devices 10A and 10B, first, the communication unit 11 performs a reception process of receiving voice data transmitted from a transmission-side device through wireless communication using BLE (step S01). , Communication step). Next, the encoding / decoding unit 12 performs a decoding process for decoding the audio data received in the reception process (step S02). At this time, the value of the missing portion of the audio data is 0.

  Subsequently, the audio data processing unit (that is, the detecting unit 13 and the erasing unit 14) performs sound quality improvement processing on the audio data (step S03). In this sound quality improvement process, first, the detection unit 13 detects a point at which the voice data changes from the silent state to the silent state or a point at which the voice data changes from the silent state to the silent state (detection step), and then The waveform including the detected change point is erased from the audio data (erase step).

  Specifically, in the above-described detection step, when the audio data changes from the silent state to the silent state as shown in FIG. It is determined whether or not the difference between the silent state value (the value at point P1 in FIG. 5B) and the silent state value (the value at point P2 in FIG. 5B) is greater than or equal to a certain value. When the detection unit 13 determines that the value is equal to or greater than a certain value, the detection unit 13 detects points (points P1 and P2 in FIG. 5B) that change from the silent state to the silent state as changing points.

  Further, when the audio data changes from the silent state to the non-silent state as shown in FIG. 5C, the detection unit 13 has a value immediately after the change to the silent state in the audio data (in FIG. 5C). It is determined whether or not the difference between the value of the point P12) and the silent state value (the value of the point P11 in FIG. 5C) is a certain value or more. When the detection unit 13 determines that the value is equal to or greater than a certain value, the detection unit 13 detects points (points P11 and P12 in FIG. 5C) that change from the silent state to the silent state as the changing points.

  Here, the above-described constant value is a value that can sufficiently reduce the noise “buzz”. For example, the value is “20000” in the speech waveform when the amplitude value is represented by 16 bits at a sampling frequency of 8 kHz in PCM.

  In the above-described detection step, the detection unit 13 recognizes that the audio data is in a silent state when the audio data value of 0 continues for a certain period. As an example of the fixed period, a sampling interval for 5 times (1/8 kHz × 5) is used.

  In the above-described erasure step, the erasure unit 14, prior to the change point (points P 1 and P 2 in FIG. 5B), when the audio data changes from the silence state to the silence state as shown in FIG. The waveform of the period t1 from the point where the value of the voice data is 0 (point P3 in FIG. 5B) to the change point is deleted. Further, when the voice data changes from the silent state to the non-silent state as shown in FIG. 5C, the erasing unit 14 follows the change point from the change points (points P11 and P12 in FIG. 5C). The waveform of the period t2 up to the point where the value of the voice data is 0 (point 13 in FIG. 5C) is deleted. Accordingly, the sound data waveform correction sections A and B shown in FIG. 5A have waveforms shown in the lower diagram of FIG. 5B and the lower diagram of FIG. 5C, respectively. . In this manner, the waveform of the portion where the value abruptly fluctuates in the sound data waveform is erased by the erasing step. In the lower diagram in FIG. 5B and the lower diagram in FIG. 5C, the value of the erased portion in the speech waveform is replaced with 0.

  Returning to the description of FIG. 4, following the sound quality improvement process (step S03), the playback unit 15 performs a sound playback process of playing back the sound data whose waveform has been deleted in the above-described deletion step (step S04, playback step). Audio data is played back.

  In the wireless communication devices 10A and 10B, the processes in steps S01 to S04 described above are repeatedly executed at predetermined intervals.

  As described above, according to the wireless communication devices 10A and 10B of the present embodiment, a change point is detected in received audio data, and a waveform including the change point is erased from the audio data. Since the waveform of the portion where the value fluctuates abruptly in the data waveform is erased, the generation of noise can be easily reduced with a low load.

  Moreover, according to such a noise reduction method, since it can be realized with a very low load, it is possible to improve the sound quality of a call while suppressing an increase in the cost of the device. In addition, although it is assumed that devices having low calculation capability such as Bluetooth (registered trademark) receivers are used as the wireless communication devices 10A and 10B, even in such a case, the wireless communication devices 10A and 10B It becomes easy to employ the above-described noise reduction method.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to above-mentioned description, A various change is possible in the range which does not deviate from the summary of this invention.

  For example, the above-described constant value can be appropriately changed according to the sampling frequency, the number of bits, the noise level to be cut, and the like.

  In addition, any wireless communication technology with low power consumption may be used, and the present invention is not limited to using Bluetooth (registered trademark).

10A, 10B Wireless communication apparatus 11 Communication unit 13 Detection unit 14 Erasing unit 15 Playback unit 20 Gateway 30 Communication network SYS Wireless communication system

Claims (9)

A wireless communication device for performing a voice call using wireless communication,
A communication unit that receives audio data transmitted from a transmission-side device; and
A detection unit for detecting, as a change point, a point at which the voice data received by the communication unit changes from a silent state to a silent state or a point at which the voice data changes from a silent state to a silent state;
An erasure unit for erasing a waveform including the change point detected by the detection unit from the audio data;
A wireless communication apparatus comprising: a reproduction unit that reproduces the audio data from which the waveform has been erased by the erasure unit. When the audio data changes from a silent state to a silent state, the detection unit has a difference between a value of the nearest non-silent state and the silent state value that changes to the silent state in the voice data is a certain value or more. When the voice data changes from a silent state to a silent state, the difference between the value immediately after the voice data changes to the silent state and the silent state value is a certain value or more. If it is determined whether or not it is equal to or more than the predetermined value, a point that changes from a silent state to a silent state or a point that changes from a silent state to a silent state is detected as the changing point,
The erasing unit has a waveform from a point where the value of the audio data before the change point is 0 to the change point, or a point where the value of the audio data after the change point is 0. The wireless communication apparatus according to claim 1, wherein the waveform up to is erased from the audio data.   The wireless communication apparatus according to claim 1, wherein the communication unit performs wireless communication using BLE.   4. The wireless communication device according to claim 1, wherein the detection unit recognizes that the audio data is in a silent state when the value of the audio data is 0 for a certain period. 5. . The wireless communication apparatus according to any one of claims 1 to 4,
A wireless communication system comprising: a gateway that is connected to a communication network and transmits / receives the audio data to / from the wireless communication device and performs protocol conversion of the audio data. A noise reduction method for a wireless communication device that performs a voice call using wireless communication,
A communication step of receiving audio data transmitted from a transmitting device;
Detecting the point where the audio data received in the communication step changes from a silent state to a silent state or a point where the voice data changes from a silent state to a silent state;
An erasing step of erasing the waveform including the change point detected in the detecting step from the audio data;
A reproduction step of reproducing the audio data from which the waveform has been erased in the erasure step. In the detection step, when the sound data changes from a silence state to a silence state, a difference between a value of the most recent silence state and a silence state value that changes to a silence state in the sound data is a certain value or more. When the voice data changes from a silent state to a silent state, the difference between the value immediately after the voice data changes to the silent state and the silent state value is a certain value or more. If it is determined whether or not it is equal to or more than the predetermined value, a point that changes from a silent state to a silent state or a point that changes from a silent state to a silent state is detected as the changing point,
In the erasing step, the waveform from the point where the value of the audio data before the change point is 0 to the change point, or the value of the audio data after the change point after the change point is 0 The noise reduction method according to claim 6, wherein the waveform up to is erased from the audio data.   The noise reduction method according to claim 6 or 7, wherein, in the communication step, wireless communication is performed using BLE.   The noise reduction method according to any one of claims 6 to 8, wherein in the detection step, the voice data is recognized as being silent when a state where the value of the voice data is 0 continues for a certain period. .

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