KR100273970B1 - Echo constraning apparatus of wireless telecommunication set - Google Patents

Abstract

end. TECHNICAL FIELD OF THE INVENTION

An apparatus for suppressing echo in a wireless terminal.

I. The technical problem to be solved by the invention

In a method of reducing echo in a wireless terminal, an apparatus for suppressing an echo phenomenon induced by a microphone or a codec by shaking the power supply stage, especially when a received voice signal is output through an audio amplifier, is provided.

All. Summary of Solution of the Invention

Apart from the rectifiers used for audio amplifiers, it is also equipped with a further rectifier connected to the codec and the microphone or a low pass filter to block the induced echo.

la. Important uses of the invention

Used for communication terminals.

Description

Echo suppression device of wireless terminal

The present invention suppresses echo in a wireless terminal, and in particular, the power terminal is shaken when a received voice signal is output through an audio amplifier, thereby inducing the microphone and the codec (hereinafter referred to as "CODEC") to the microphone and the codec (analog digital converter and digital analog converter). The present invention relates to an apparatus for suppressing echo phenomenon which is transmitted again.

First, the echo is generated as follows. The first path is that the sound output from the speaker is echoed back into the microphone. The second path is the oscillation of the power stage due to the large current consumption of the audio amplifier, which is induced in the microphone power stage and the codec power stage, causing echo. The voltage used for sound output is about 6V _PP , and about 100 mA is used. Therefore, large current is converted into sound and consumed, and power stage is shaken. At this time, the power terminal is induced by the variation of the voltage and current of the speaker output to the transmitter microphone power source and the codec is a path that is transmitted again through the RF unit. The other party receiving the message for the above two reasons has a problem of hearing an echoed signal.

Accordingly, an object of the present invention is to provide an apparatus for suppressing an echo phenomenon induced by a microphone or a codec by shaking a power supply stage when a voice signal received from a wireless terminal is output through an audio amplifier.

In order to achieve the above object, the present invention provides a codec for converting an analog signal into a digital signal or a digital signal into an analog signal, an audio amplifier for amplifying the analog signal transmitted from the codec and outputting the same to a speaker; Or a microphone for transmitting a signal to the codec, a first rectifier for supplying power to the microphone and the codec, and a second rectifier for supplying power to the audio amplifier.

Or a codec for converting an analog signal into a digital signal or an analog signal into an analog signal, an audio amplifier for amplifying the analog signal transmitted from the codec and outputting the same to a speaker, and receiving a voice and transmitting a signal to the codec. And a low pass filter positioned between the microphone, the codec, the audio amplifier, and a rectifier for supplying power to the microphone, and the rectifier connected to the microphone or the codec.

1A is a block diagram of a conventional wireless terminal

1B is a block diagram of a power supply unit for supplying power to a conventional wireless terminal

2 is a block diagram of a power supply unit for suppressing echo according to an embodiment of the present invention;

Figure 3a is a block diagram for suppressing echo according to another embodiment of the present invention

3B is a circuit diagram according to another embodiment of the present invention.

3c shows a frequency response curve of a low pass filter.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In addition, specific details appear in the following description, which is provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific matters. Will be self-evident. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1A is a block diagram of a conventional wireless terminal, and FIG. 1B is a block diagram of a power supply unit for supplying power to a conventional wireless terminal.

The controller 100 of the wireless terminal controls the overall operation of the wireless terminal. The user interface includes a key input unit 150 and a display unit 140. The key input unit 150 includes a plurality of numeric keys and function keys for performing various functions, and outputs key data to the controller 100 by an external operation. The display unit 140 is a display device such as a liquid crystal display (LCD). The display unit 140 displays the state of the wireless terminal or the progress of the program under the control of the controller 100. The memory 130 includes a ROM that stores an operating program, an electrically programmable EEPROM, and a RAM. The codec 110 modulates a voice signal input from a microphone and converts the voice signal into voice data, demodulates the voice data input from the RF unit 160 into a voice signal, and outputs the voice signal through a speaker. The audio amplifier 120 amplifies the analog voice signal received from the codec 110 and outputs the same to the speaker. The RF unit 160 is controlled by the controller 100 and converts a signal output from the controller 100 into a wireless signal. In addition, the RF unit 160 converts the wireless signal received through the antenna into a desired signal and outputs it.

FIG. 1B supplies power to the microphone Vcc1, the codec 110 (Vcc2), and the audio amplifier 120 (Vcc3) through the processing of the DC / DC converter 180 and the rectifier 181 with the power applied from the battery 170. do.

In general, a call is made and the digital signal received through the RF unit 160 is converted into an analog signal in the codec 110 and output to the audio amplifier. The audio amplifier 120 amplifies the input analog signal and outputs it to the speaker. The voltage and current consumed at this time are very large as described in the technical field to which the invention belongs and the prior art in that field. For this reason, the power supply Vcc1 applied to the microphone in the rectifier 181 and the power supply Vcc2 applied to the codec 110 are affected. As described above, the fluctuation of the power stage due to the large current consumption is induced in the microphone and the codec 110 to cause an echo.

2 is a block diagram of a power supply to suppress echoes according to an exemplary embodiment of the present invention.

3A is a block diagram for suppressing echo according to another embodiment of the present invention.

3B is a circuit diagram according to another embodiment of the present invention.

3C is a diagram illustrating a frequency response curve of a low pass filter.

In FIG. 2, a DC / DC converter 180 includes a second rectifier 183 for providing a power supply Vcc3 provided to the audio amplifier 120, and a first rectifier 182 for providing a power supply Vcc1 provided to the microphone and a power supply Vcc2 provided to the codec 110. Connected to. That is, the power stage may be shaken to prevent the microphone and codec 110 from being abandoned.

Figure 3a is a low pass filter 300 between the microphone and the rectifier 181 supplying Vcc1 to block the echo to the microphone input. In this case, as shown in FIG. 3B, the low pass filter 300, which is easily used, is composed of a resistor R2 connected in series with a rectifier 181 and a microphone, and a capacitor C1 having one end connected between the resistor R2 and the microphone and the other end connected to ground. Filter. The low pass filter is also connected between the rectifier 181 and the codec 110 to suppress the echo phenomenon caused by being applied to the codec 110. 3C is a frequency response curve of the low pass filter, and the cutoff frequency CUT OFF FREQUENCY is obtained by Equation 1 below.

If the resistance R2 is 5.6KΩ and the capacitance C1 is 10μF, according to Equation 1, the cutoff frequency is 1 / (2π56000 * 0.00001) to 2.8Hz. In general, the audible frequency that a human can hear is 20 Hz to 20,000 Hz, so the cutoff frequency may be 20 Hz or less.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention provides an audio system by setting a separate rectifier for use in an audio amplifier to block echoes induced by an audio amplifier to a microphone or a codec, or by installing a low pass filter before power is supplied to the microphone or codec. The echo phenomenon caused by the use of a large current of the amplifier can be suppressed.

Claims (5)

A codec for converting an analog signal into a digital signal or an analog signal into an analog signal, an audio amplifier for amplifying the analog signal transmitted from the codec and outputting the same to a speaker, and a microphone for receiving a voice and transmitting a signal to the codec. In the wireless terminal having a, A first rectifier for supplying power to the microphone and codec, And a second rectifier for supplying power to the audio amplifier. A codec for converting an analog signal into a digital signal or an analog signal into an analog signal, an audio amplifier for amplifying the analog signal transmitted from the codec and outputting the same to a speaker, and a microphone for receiving a voice and transmitting a signal to the codec. And a rectifier for supplying power to the codec, the audio amplifier, and the microphone, A low pass filter is provided between a rectifier connected to a microphone or between a rectifier connected to a codec. The method of claim 2, And a cutoff frequency of the low pass filter is 20 hertz or less. The method of claim 2, The low pass filter, A resistor connected in series with the rectifier and the microphone, Echo suppression apparatus of the wireless terminal, characterized in that the one end is connected between the resistor and the microphone and the other end is composed of a capacitance connected to the ground. The method of claim 2, The low pass filter, A resistor connected in series with the rectifier and the codec; Echo suppression apparatus of a wireless terminal, characterized in that the one end is connected between the resistor and the codec and the other end is composed of a capacitance connected to the ground.