KR20090110069A - How to reduce howling of a wireless microphone - Google Patents

Abstract

The present invention relates to a wireless microphone. The wireless microphone according to the present invention includes a wireless transmission means for amplifying and outputting a voice signal input from the outside to a predetermined gain value, and receiving the output voice signal, and howling to the wireless transmission means when a howling is detected from the received voice signal. And wireless reception means for transmitting the detection information, wherein the wireless transmission means adjusts the gain value upon receiving the howling detection information. According to the present invention, the howling generated in the voice signal output from the wireless microphone can be effectively reduced, so that the doctor can communicate more clearly and accurately. In addition, pairing of the wireless transmitting means and the wireless receiving means included in the wireless microphone can be performed easily.

Description

How to reduce howling of a wireless microphone {HOWLING REDUCTION METHOD OF WIRELESS MICROPHONE}

The present invention relates to a wireless microphone, and more particularly, to a method of reducing howling occurring in a wireless microphone.

A microphone (MIC) is an electroacoustic transducer used to convert acoustic energy into electrical energy. Operating principle According to the structure, the dynamic microphone and condenser microphone occupy most of the microphones currently used. In addition, it is divided into piezoelectric microphone using piezoelectric phenomenon, carbon microphone using contact resistance of carbon particles, omnidirectional pressure microphone and so on. . It is also classified into omnidirectional and unidirectional microphones according to the directivity characteristics.

Recently, the wireless microphone (Wireless Microphone) is in the spotlight, the wireless microphone is a device that replaces the cord wirelessly is made of a wireless transmission means of the microphone type and the wireless receiving means connected to the speaker is integrated.

Since the cable does not need to be connected to the microphone, singers, moderators, and delegates can freely move the wireless microphone and record without the other person noticing. Recently, wireless microphones have been released in various forms such as hand held type, pin pack type, and head type for the convenience of the user.

On the other hand, the wireless microphone may generate noise in the process of transmitting a voice signal through wireless communication. In particular, when the distance between the wireless transmitting means and the wireless receiving means is close, a howling phenomenon may occur in which the voice outputted through the wireless receiving means is repeatedly amplified and output again to the wireless transmitting means. When howling occurs, low-frequency oscillations similar to noise occur continuously, which makes communication difficult.

Therefore, the technical problem to be achieved by the present invention is to provide a wireless microphone that can effectively reduce the howling.

Wireless microphone according to an embodiment of the present invention for achieving the technical problem, a wireless transmission means for amplifying and outputting a voice signal input from the outside to a predetermined gain value, and receives the output voice signal, the received And wireless reception means for transmitting howling detection information to the wireless transmission means when the howling is detected from the voice signal, wherein the wireless transmission means adjusts the gain value upon receiving the howling detection information.

The wireless transmission unit may include a microphone unit for collecting the voice signal, an AMP for amplifying the voice signal to a predetermined gain value, a first communication module for transmitting the voice signal to the wireless receiving unit, and the wireless receiving unit from the wireless receiving unit. When receiving the howling detection information may include a first control unit for reducing the gain value of the AMP.

The apparatus may further include a modulator configured to convert the voice signal into a digital signal, and a filter configured to pass only a signal having a predetermined frequency band among the voice signals.

The wireless receiving unit may include a howling detector for detecting howling from the received voice signal and generating howling detection information, a second control unit which delays the received voice signal when the howling is detected, and the howling detection information. It may include a second communication module for transmitting to the transmitting means.

The apparatus may further include a demodulator configured to convert the received voice signal into an analog signal, and an amplifier configured to amplify the received voice signal.

The howling detector may determine that the howling is detected when the amplitude exceeds a reference value in the specific frequency band of the received voice signal or when the amplitude maintains the peak value for a specific time.

The first communication module and the second communication module may communicate in an adaptive frequency hopping (AFH) scheme.

When receiving the pairing request signal from a plurality of wireless transmitting means, the wireless receiving means compares the received field strength (RSSI) of the pairing request signal and makes a pairing request to the wireless transmitting means having the maximum receiving field strength. You can authenticate.

When performing the pairing request authentication, it is possible to exchange a Bluetooth address or an identification name with the wireless transmission means.

The pairing request signal may be deleted for the wireless transmission means having a smaller reception field strength than the wireless transmission means having the maximum reception field strength.

According to another embodiment of the present invention, in the howling reduction method of a wireless microphone including a wireless transmitting means and a wireless receiving means, detecting a howling signal from a voice signal received from the wireless transmitting means, when the howling is detected Delaying the received voice signal, and transmitting howling detection information to the wireless transmission means.

According to another embodiment of the present invention, in the howling reduction method of a wireless microphone including a wireless transmitting means and a wireless receiving means, collecting a voice signal input from the outside, amplifying the voice signal to a predetermined gain value Outputting the voice signal to the wireless receiving means, and decreasing the gain value when receiving the howling detection information from the wireless receiving means.

The method may further include requesting a pairing request from the wireless receiving unit, and exchanging a Bluetooth address or an identification name with the wireless receiving unit when the pairing request is authenticated from the wireless receiving unit.

As described above, according to the present invention, the howling generated in the voice signal output from the wireless microphone can be effectively reduced, so that a doctor can be communicated more clearly and accurately. In addition, pairing of the wireless transmitting means and the wireless receiving means included in the wireless microphone can be performed easily.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

First, a wireless microphone according to an embodiment of the present invention will be described with reference to FIG. 1. The wireless microphone consists of a wireless transmitting means 100 and a wireless receiving means 200.

1 is a schematic diagram illustrating a wireless transmitting means and a wireless receiving means according to an embodiment of the present invention.

As shown in Figure 1, the wireless transmission means 100 is provided with a handle for inputting a voice in a state held by the user, it is made of a form that is not connected to the cable line. The wireless receiving unit 200 may be configured in the form of a jack or a microphone plug, and is inserted into the microphone input terminal 310 formed in the output device 300 such as a conventional amplifier. Therefore, when the user speaks through the wireless transmitter 100, the voice is amplified and transmitted to the outside through the output device 300 connected to the wireless receiver 200. The wireless receiving means 200 and the wireless transmitting means 100 may perform bidirectional communication in a Bluetooth manner.

Hereinafter, the wireless transmitter 100 and the wireless receiver 200 according to the embodiment of the present invention will be described in detail with reference to FIGS. 2A and 2B.

2A is a diagram showing the configuration of a wireless transmission means according to an embodiment of the present invention.

The wireless transmitter 100 includes a microphone 110, a modulator 120, an AMP 130, a filter 140, and a first main chip 150.

First, the microphone unit 110 includes a circuit such as a piezoelectric element, and collects a voice signal input from a user and transmits the voice signal to the modulator 120.

The modulator 120 modulates an analog voice signal received from the microphone 110 into a digital signal.

The AMP 130 receives the voice signal from the modulator 120 and amplifies the voice signal to an appropriate level according to the set gain value. The AMP 130 amplifies the voice signal to prevent the modulated voice signal from being attenuated in air.

The filter unit 140 includes a band pass filter (BPF), and mainly passes a band signal of 150 Hz to 6 KHz. Since howling occurs mostly in high frequency bands, a band pass filter is used to remove frequency components in bands other than the voice band.

The first main chip 150 includes a first control unit 152 and a first communication module 154. When the howling is detected from the wireless receiving unit 200, the first controller 152 controls the AMP 130 to reduce the gain of the voice signal. The first communication module 154 is a short-range RF communication module for transmitting a voice signal to the wireless receiving means 200 through an antenna (not shown), and follows a Bluetooth communication protocol.

2B is a view showing the configuration of a wireless receiving means according to an embodiment of the present invention.

The wireless receiver 200 includes a second main chip 210, a demodulator 220, an amplifier 230, and a howling detector 240.

The second main chip 210 includes a second communication module 212 and a second control unit 214. Like the first communication module 154, the second communication module 212 is configured as a short range RF communication module and follows a Bluetooth communication protocol.

The second communication module 212 receives a voice signal from the first communication module 154 through an antenna (not shown). When the howling detection unit 240 detects the howling, the second controller 214 delays and outputs the voice signal. In this case, the voice signal may be delayed in units of milliseconds according to the howling is detected.

The demodulator 220 demodulates the digital signal into an analog voice signal. The amplifying unit 230 amplifies the weak signal of a weak size and outputs it to the output device 300. Before the wireless transmitter 100 and the wireless receiver 200 are paired, the amplifier 230 maintains a mute state.

The howling detector 240 detects the howling from the voice signal output from the amplifier 230 to the output device 300, and when the howling is detected, notifies the howling detection information to the second main chip 210.

Hereinafter, a process of performing pairing between the wireless transmitter 100 and the wireless receiver 200 and transmitting a voice signal will be described with reference to FIGS. 3 to 4.

First, in order to use a wireless microphone, a process of performing mutual authentication through a procedure called pairing between the wireless transmitting means 100 and the wireless receiving means 200 is required. 3 is a flowchart illustrating a method for performing pairing between a wireless transmitting means and a wireless receiving means according to an embodiment of the present invention.

First, the user moves the wireless transmission means 100 to the wireless reception means 200 (S310). In general, since the wireless receiving means 200 is fixed inside a lecture room or a conference room, the user may bring the wireless transmitting means 100 into proximity within about 1 m from the wireless receiving means 200.

When the user presses an input button installed in the wireless transmitting means 100, the wireless transmitting means 100 transmits a pairing request signal to the wireless receiving means 200 (S320).

Here, in order for the wireless receiving means 200 to correctly receive the pairing request signal, the user may turn off the power of the wireless receiving means 200 and set it to a reset state. Here, when the wireless receiving means 200 is muted, crosstalk that may occur when pairing request signals may be reduced.

When the pairing request signal is received, the wireless receiving means 200 determines whether a plurality of pairing request signals have been received within a predetermined time (S325). If only one pairing request signal is received, the wireless receiving means 200 authenticates the pairing request (S330).

Here, when the wireless receiving means 200 receives a pairing request signal from the plurality of wireless transmitting means 100 in substantially the same time zone, the wireless receiving means 200 is a pairing request transmitted from the plurality of wireless transmitting means 100 Received Signal Strength Input (RSI) of the signal is measured (S340). Since the wireless receiving means 200 recognizes the RF power of the signal generated by the wireless transmitting means 100 as the received electric field strength, it is possible to determine whether the wireless transmitting means 100 is in close proximity through the received electric field strength. .

Then, when the wireless transmission means 100 is detected (S345) having the highest received electric field strength (S345), the wireless receiving means 200 authenticates the pairing request to the corresponding wireless transmission means 100 (S330). That is, since the greater the electric field strength, the closer the distance is, the wireless receiving means 200 performs pairing with the wireless transmitting means 100 at the closest distance. In addition, when one pairing request signal is received, the wireless receiving means 200 authenticates the pairing request.

When the wireless receiving means 200 transmits the pairing authentication signal to the wireless transmitting means 100 (S350), the wireless transmitting means 100 and the wireless receiving means 200 is in a connection mode (S360).

When the connection mode is entered, the wireless transmission means 100 and the wireless reception means 200 exchange an address (Bluetooth Address) or identification name (PIN code) for the counterpart device and store them in each unique memory. In addition, the wireless receiving unit 200 provides a path for releasing the mute state and transmitting the voice to the outside.

On the other hand, the wireless receiving means 200 deletes the pairing request signal for the wireless transmission means 100 indicating a small value of the received electric field strength of the pairing request signal (S370). Although not shown in FIG. 3, even when the wireless transmitting means 100 is already paired with another wireless transmitting means at the time when the wireless transmitting means 100 transmits a pairing request signal to the wireless receiving means 200, the wireless transmitting means also performs wireless transmission. The means 100 deletes the received pairing request signal.

As the wireless transmitter 100 deletes the pairing request signal, the wireless transmitter 100 and the wireless receiver 200 maintain a disconnection mode (S380).

As such, according to an embodiment of the present invention, since the wireless transmitting means 100 or the wireless receiving means 200 does not need to inquire the counterpart device and input a password, the user can conveniently perform pairing. It also prevents crosstalk with other devices.

When pairing is completed between the wireless transmitter 100 and the wireless receiver 200 as described above, the voice signal input to the wireless transmitter 100 is transmitted to the wireless receiver 200 in an RF communication manner. Hereinafter, a communication method of the first communication module 154 included in the wireless transmitting means 100 and the second communication module 212 included in the wireless receiving means 200 will be described with reference to FIG. 4.

4 is a flowchart illustrating a communication method between a first communication module and a second communication module according to an embodiment of the present invention.

The first communication module 154 and the second communication module 212 use a frequency hopping spread spectrum (FHSS) to reduce data lost during communication. The frequency hopping spread spectrum refers to a spread spectrum method in which a frequency is changed and transmitted over time without fixing a frequency in a wireless communication. However, since the 2.4 GHz band mainly used for the frequency hopping spread spectrum is a frequency band that is allowed to be used in common, some interference with the WLAN using the same band may occur, causing a disconnection in communication.

Accordingly, according to an exemplary embodiment of the present invention, the first communication module 154 and the second communication module 212 may adjust the frequency band through an adaptive frequency hopping (AFH) method in order to improve the quality of the voice signal. Can change.

Adaptive frequency hopping is not a general Bluetooth communication method that hops all channels of Bluetooth and about 80 channels, but remembers the frequency band where interference occurred in the communication process, skips the corresponding frequency and Hopping is an active hopping scheme.

According to FIG. 4, the first communication module 154 transmits an audio signal including voice signals for all channels to the second communication module 212 in the form of packet data (S410). Here, the packet type data is attached with a frequency hopping header in which frequency mapping information is recorded.

The second communication module 212 checks an error rate for each frequency band based on the frequency hopping header (S420). The error rate is calculated by dividing the total information transmission error caused by the transmission medium by the total information transmitted.

The second communication module 212 transmits error information to the first communication module 154 with respect to a channel having an error rate higher than the reference value, that is, a channel with crosstalk (S430). In addition, the first communication module 154 adjusts the hopping sequence by excluding a frequency band corresponding to a channel having a crosstalk (S440).

The first communication module 154 transmits information indicating that the hopping frequency mapping is changed to the second communication module 212 (S450), and the second communication module 212 transmits an acknowledgment message (ACK) to the first communication. By passing to module 154 (S460), adaptive frequency hopping is completed (S470).

As described above, according to an exemplary embodiment of the present invention, the first communication module 154 and the second communication module 212 change the frequency band through an adaptive frequency hopping (AFH) method to improve the quality of the voice signal and You can reduce the loss of data that occurs.

On the other hand, howling may occur as the distance between the wireless transmitting means 100 and the wireless receiving means 200 gets closer. Hereinafter, referring to FIGS. 5 to 6b, the wireless transmitting means 100 and the wireless receiving means ( The following describes how to reduce the howling that occurs between 200).

5 is a flowchart illustrating a method of reducing a howling according to an exemplary embodiment of the present invention, FIG. 6A is an exemplary diagram illustrating a frequency domain characteristic of a howling signal, and FIG. 6B is an exemplary diagram illustrating a time domain characteristic of a change of a howling signal. .

First, as shown in FIG. 5, the howling detector 240 detects a howling from a voice signal output to the output device 300 (S510). The howling detector 240 may detect howling by detecting a change in a voice signal in a frequency domain or a time domain, as shown in FIG. 6A or 6B.

As shown in FIG. 6A, when the amplitude of the voice signal increases significantly in comparison with the reference level, the howling detector 240 determines that the howling has occurred. In addition, as shown in FIG. 6B, when the amplitude of the voice signal continuously increases for a predetermined time to reach a peak value, the howling detector 240 determines that the howling has occurred.

The howling detector 240 transmits the howling detection information to the second main chip 210 indicating the howling detection when the howling is detected. Then, the second control unit 214 delays the voice signal to reduce the howling, thereby changing the phase of the voice signal (S520). In addition, the second communication module 212 transmits howling detection information to the first communication module 154 (S530).

When the first communication module 154 receives the howling detection signal (S540), the first controller 152 controls the AMP 130 to reduce the gain of the voice signal (S550).

Therefore, according to the embodiment of the present invention, when the howling is detected, the output of the audio signal is delayed and the gain of the audio signal is adjusted. Therefore, the howling generated as the distance between the wireless transmitter 100 and the wireless receiver 200 approaches can be effectively removed.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a schematic diagram illustrating a wireless transmitting means and a wireless receiving means according to an embodiment of the present invention.

2A is a diagram showing the configuration of a wireless transmission means according to an embodiment of the present invention.

2B is a view showing the configuration of a wireless receiving means according to an embodiment of the present invention.

3 is a flowchart illustrating a method for performing pairing between a wireless transmitting means and a wireless receiving means according to an embodiment of the present invention.

4 is a flowchart illustrating a communication method between a first communication module and a second communication module according to an embodiment of the present invention.

5 is a flowchart illustrating a method of reducing a howling according to an embodiment of the present invention.

6A is an exemplary diagram illustrating frequency domain characteristics of a howling signal.

6B is an exemplary diagram illustrating a time domain characteristic of a change in the howling signal.

Claims (17)

Wireless transmission means for amplifying and outputting a voice signal input from the outside to a predetermined gain value, and And wireless reception means for receiving the output voice signal and transferring howling detection information to the wireless transmission means when a howling is detected from the received voice signal. And the wireless transmitting means adjusts the gain value upon receiving the howling detection information. The method of claim 1, The wireless transmission means, A microphone unit for collecting the voice signal, AMP for amplifying the voice signal to a predetermined gain value, A first communication module for transmitting said voice signal to said wireless receiving means, and And a first control unit which reduces a gain value of the AMP when receiving the howling detection information from the wireless receiving unit. The method of claim 2, A modulator for converting the voice signal into a digital signal, and The wireless microphone further comprises a filter for passing only a signal of a predetermined frequency band of the voice signal. The method of claim 3, The wireless receiving means, A howling detector for detecting howling from the received voice signal and generating howling detection information; A second controller which delays the received voice signal when the howling is detected; and And a second communication module for transmitting the howling detection information to the wireless transmission means. The method of claim 4, wherein A demodulator for converting the received voice signal into an analog signal, and And amplifying unit for amplifying the received voice signal. The method of claim 4, wherein The howling detector, And a howling is detected when the amplitude exceeds a reference value in the specific frequency band of the received voice signal or when the amplitude maintains a peak value for a specific time. The method of claim 4, wherein And the first communication module and the second communication module communicate by adaptive frequency hopping (AFH). The method of claim 1, The wireless receiving means, Receiving a pairing request signal from a plurality of wireless transmitting means, comparing the received field strength (RSSI) of the pairing request signal, and authenticating the pairing request with respect to the wireless transmitting means having the maximum receiving field strength. wireless microphone. The method of claim 8, And performing a pairing request authentication, exchanging a Bluetooth address or an identification name with the wireless transmitting means. The method of claim 8, And a pairing request signal is deleted for the wireless transmission means having a smaller reception field strength than the wireless transmission means having the maximum reception field strength. In the method of reducing howling of a wireless microphone comprising a wireless transmitting means and a wireless receiving means, Detecting a howling signal from the voice signal received from the radio transmitting means; Delaying the received voice signal when the howling is detected, and And transmitting the howling detection information to the wireless transmission means. The method of claim 11, Detecting the howling signal, The howling reduction method of the wireless microphone, characterized in that it is determined that howling is detected when the amplitude exceeds a reference value or the amplitude maintains a peak value for a specific time in the received voice signal. The method of claim 12, Receiving a pairing request signal from a plurality of wireless transmitting means, comparing the received field strength (RSSI) of the pairing request signal, and authenticating the pairing request with respect to the wireless transmitting means having the maximum receiving field strength. How to reduce howling of a wireless microphone. The method of claim 13, And performing a pairing request authentication, exchanging a Bluetooth address or an identification name with the wireless transmission means. The method of claim 13, And the pairing request signal is deleted for the wireless transmission means having a smaller reception field strength than the wireless transmission means having the maximum reception field strength. In the method of reducing howling of a wireless microphone comprising a wireless transmitting means and a wireless receiving means, Collecting a voice signal input from the outside, Amplifying the voice signal to a constant gain value; Outputting the voice signal to the wireless receiving means; and And reducing the gain value when receiving howling detection information from the wireless receiving means. The method of claim 16, Requesting a pairing request to the wireless receiving means; and And if the pairing request is authenticated from the wireless receiving means, exchanging a Bluetooth address or an identification name with the wireless receiving means.

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