JP5846808B2 - Gain adjustment system - Google Patents

Description

The present invention relates to a gain adjustment system that adjusts a microphone gain of a radio having a noise canceling function.

  In wireless terminals, it is necessary to consider use in various environments, and countermeasures in consideration of ambient noise have been dealt with in various forms so far (see, for example, Patent Documents 1 to 3). .

JP 2000-236280 A JP-A-11-187086 JP 10-187193 A

However, the conventional radio equipment employs a method of extracting only an audio signal using a noise canceling IC, but there are problems that the amount of canceling noise is limited and the price of the IC itself is expensive. It was.
The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide a gain adjustment system capable of accurately adjusting the gain of a radio in a short time .

To achieve the above object, according to a first aspect of the present invention, there is provided a first microphone that collects voice and ambient noise, and a second microphone that is attached to a position different from the first microphone and collects ambient noise. microphone and, second channel the second microphone and the first transducer and the first amplifier output of the first amplifier to digital conversion by the first microphone to amplify the input to the first channel to be connected is connected A stereo codec including a second amplifier for amplifying an input to the second amplifier and a second converter for digitally converting an output of the second amplifier; a first digital signal by the first converter output from the stereo codec; A signal processing unit that cancels in-phase noise components by software processing of the second digital signal by the two converters and outputs only the audio signal; A gain adjustment system for adjusting the gain of said first amplifier and said second amplifier in a radio apparatus and a transmission unit that transmits to convert the output signal from the serial signal processing section in the radio signal,
A set unit for setting the radio device in a predetermined state, and the same positional relationship with respect to the first microphone and the second microphone of the radio device in a state where the radio device is set in the set unit. A gain adjusting device including a first speaker and a second speaker arranged in such a manner as to be connected to the first speaker and the second speaker, and output a sound for adjustment from the first speaker and the second speaker; A sound generation unit and a computer connected to the radio device via the set unit of the gain adjustment device and a computer connected to the sound pressure adjustment unit are provided. Then, with the computer, the sound generator is operated in a state where the wireless device is set in the set unit of the gain adjusting device, and the time is different from each of the first speaker and the second speaker. The first digital signal output from the stereo codec of the radio device is captured in a state where the sound pressure sound is output and the sound is output only from the first speaker, and the amplitude value is taken as the first amplitude value. Is calculated and stored, and the second digital signal output from the stereo codec of the radio is captured in a state where the sound is output only from the second speaker, and the amplitude value is calculated as the second amplitude value. Then, the calculated second amplitude value is compared with the stored first amplitude value, and the gain of the second amplifier is set so that the difference is within a predetermined value. It is obtained so as to adjust.

That is, according to the present invention, it is possible to provide a gain adjustment system that can perform gain adjustment of a radio device with high accuracy in a short time .

The block diagram which shows the radio | wireless machine which concerns on 1st Embodiment. The block diagram which shows the microphone gain adjustment apparatus of the radio | wireless machine which concerns on 2nd Embodiment. The figure which shows the sampling method of a microphone input level. The figure which shows the microphone gain adjustment installation of the radio | wireless machine which concerns on 3rd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
The first embodiment of the present invention realizes a noise canceling function by DSP software processing with a hardware configuration using a stereo codec.
FIG. 1 is a block diagram illustrating a configuration of a wireless device according to the first embodiment.

  The radio includes two microphones 11-1 and 11-2, a stereo codec 12, a digital signal processor (DSP) 13, a digital / analog converter (D / A converter) 14, an orthogonal converter 15, power An amplifier (PA: Power Amplifier) 16, an antenna 17, and a micro processing unit (MPU: Micro Processing Unit) 18 are provided.

  An audio microphone (audio microphone) 11-1 is connected to the L channel (Lch) of the stereo codec 12, and an ambient noise microphone (ambient noise microphone) 11-2 is connected to the R channel (Rch) to generate an audio signal. And ambient noise signals simultaneously. The stereo codec 12 amplifies the captured audio signal and ambient noise signal by programmable gain amplifiers (PGA) 121 and 122 with predetermined gain adjustment values, respectively, and an analog / digital converter (ADC) 123, A / D conversion is performed by 124. The MPU 18 outputs an I2S (Inter-IC Sound) signal including an audio signal and an ambient noise signal output from the stereo codec 12 to the DSP 13.

  The DSP 13 takes in the I2S signal from the MPU 18, cancels out the in-phase noise component of the audio signal and the ambient noise signal by software processing, and outputs only the audio signal. The noise-canceled audio signal output from the DSP 13 is analog converted by the D / A converter 14, modulated by the orthogonal converter 15, power amplified by the PA 16, and transmitted from the antenna 17. In this way, clear voice without noise can be transmitted to the other party.

  As described above, according to the first embodiment, the hardware configuration that realizes the noise canceling function using the stereo codec eliminates the need for the noise canceling IC. In addition, it is advantageous in terms of current consumption, which is an important parameter in the radio. Further, by performing noise cancellation by DSP soft processing, the degree of freedom of the noise cancellation level is increased, and ambient noise can be efficiently reduced.

(Second Embodiment)
In order to perform noise cancellation in the wireless device according to the first embodiment, the audio code 11-1 and the ambient noise microphone 11-2 are used to simultaneously capture the audio signal and the ambient noise signal with the stereo codec 12, and the DSP. By canceling out the in-phase noise component in the process, only the voice component is modulated, and clear voice without noise can be transmitted to the other party.

  However, in order to remove the noise component, it is necessary to adjust the input level difference between the voice microphone 11-1 and the ambient noise microphone 11-2 with considerable accuracy (for example, within 0.5 dB). As a general microphone level adjustment method, there is a method in which sound is input from a microphone, modulation is performed using this signal, and transmission deviation is measured, but this method also includes errors in the transmission system in the adjustment accuracy. become.

Therefore, in the second embodiment of the present invention, in the wireless device according to the first embodiment, the microphone level is adjusted at the microphone input stage of the codec, thereby adjusting with high accuracy without including the measurement error of the wireless transmission system. How to do will be described.
FIG. 2 is a block diagram showing the configuration of the second embodiment. A wireless device 1A in FIG. 2 is obtained by adding a serial data interface (UART: Universal Asynchronous Receiver Transmitter) 19 to the configuration of the wireless device 1 in FIG. A personal computer (PC) 3 is connected to the serial interface 19 via the level converter 2. In FIG. 2, the same parts as those in FIG.

  The MPU 18 distributes the I2S signal including the audio signal and the ambient noise signal output from the stereo codec 12 to the DSP 13 and the UART 19. The UART 19 and the level converter 2 exchange data between the MPU 18 and the PC 3.

Next, the gain adjustment operation of the wireless device in the second embodiment will be described with reference to FIG.
(1) An audio signal of a specified level is input to the audio microphone 11-1 and the ambient noise microphone 11-2, and the audio signal and the ambient noise signal are captured by the Lch and Rch of the stereo codec 12, and each signal is assigned to the PGA 121, Amplified by 122 and digitally converted by ADCs 123 and 124.

  (2) The MPU 18 extracts a digital audio value from the ADC 123 of the audio microphone 11-1 and supplies it to the PC 3 as microphone level data via the UART 19 and the level converter 2. The PC 3 measures the maximum value 3 points and the minimum value 3 points, calculates the amplitude value G1 from the average value, and obtains the gain adjustment value of the PGA 121 from the amplitude value G1. The PC 3 transmits the gain adjustment value to the MPU 18 via the level converter 2 and the UART 19, and the MPU 18 registers this gain adjustment value in the memory of the PGA 121.

  (3) The MPU 18 extracts a digital voice value from the ADC 124 of the ambient noise microphone 11-2 and supplies it to the PC 3 as microphone level data via the UART 19 and the level converter 2. The PC 3 calculates the amplitude value G2 by measuring the gain in the same manner as (2) above. The PC 3 transmits a control command via the level converter 2 and the UART 19, varies the gain of the PGA 122, and adjusts the amplitude value G2 to be the same level as the amplitude value G1.

(4) The PC 3 ends the adjustment when the level difference between the amplitude value G 2 and the amplitude value G 1 is equal to or smaller than a predetermined value, and registers the gain adjustment value in the memory of the PGA 122.
As described above, according to the second embodiment, the microphone input level is adjusted at the microphone input stage of the codec, so that the measurement error of the wireless transmission system is not included as in the conventional method, and the adjustment is performed with high accuracy. Is possible.

(Third embodiment)
In the third embodiment of the present invention, a microphone gain adjustment method performed in the radio production facility of the first embodiment will be described. In order to perform software processing by the DSP for noise cancellation, the input levels from the voice microphone and the ambient noise microphone need to be approximately the same (within 0.5 dB). However, the sensitivity deviation of the microphones used is ± 2 dB, and the difference in input level between each microphone is about 5 dB due to the ventilation of the dustproof net between the microphone and the case and the microphone integration error. It will occur. Therefore, in order to make this difference 0.5 dB or less, it is necessary to adjust the microphone gain in order to adjust the gain of one microphone amplifier (PGA 122) and make the input level difference 0.5 dB or less.

  However, for example, when the gain adjustment of the wireless device is performed with one speaker, the mounting position of the microphone for sound and the microphone for ambient noise is different, so that it takes time to readjust the distance and height of the speaker. In addition, since there is a movable part in the speaker fixing part of the apparatus, an error is likely to occur in positioning accuracy, and there is a problem in terms of durability at the time of mass production use. Therefore, a third embodiment for improving such a problem is proposed.

FIG. 4 is a diagram showing a microphone gain adjustment facility for a radio device according to the third embodiment of the present invention. In FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
The microphone gain adjusting device 6 includes a voice microphone speaker 61-1 and an ambient noise microphone speaker 61-2 fixed at a distance of 5 cm from the wireless device 1, and the speakers 61-1 and 61-2 are connected to the audio amplifier 5. Connected. The oscillator 4 connected to the audio amplifier 5 is connected to the PC 3 so that the output level can be controlled.
The wireless device 1 is an input / output terminal for connecting the PC 3 and accessories such as an external speaker and a microphone via the level converter 2 in order to receive a control command for adjusting the gain of the microphone amplifier in each microphone. A UDC (Universal Device Connector) is connected.

Next, the operation of the third embodiment will be described.
(Speaker sound pressure calibration of microphone gain adjustment equipment)
The sound pressure calibration (91 dBSPL) of the voice microphone speaker and the ambient noise speaker will be described. Each speaker 61-1 and 61-2 is calibrated by varying the output of the oscillator 4 using a sound level meter so that the sound pressure becomes 91 dBSPL. The adjustment value at this time is stored in the memory of the PC 3 and is output when each microphone gain is adjusted.

(Microphone gain adjustment procedure)
(1) The wireless device 1 is set in the microphone gain adjusting device 6.
(2) The audio amplifier 5 of the microphone gain adjusting device 6 is operated, the value of the oscillator 4 acquired in advance is output, and the sound pressure of 91 dBSPL is output from the audio microphone speaker 61-1. The input level of the voice microphone 11-1 is measured by a control command from the PC 3, and the measured value is stored in the PC 3.

(4) Next, in order to measure the input level of the ambient noise microphone 11-2, the value of the oscillator 4 (the output value of the ambient noise microphone speaker 61-1) acquired in advance is output, and the ambient noise microphone is output. A sound pressure of 91 dBSPL is output from the speaker 61-1.
(5) The input level of the ambient noise microphone 11-2 is measured by a control command from the PC 3, and compared with the input level of the voice microphone 11-1 stored in the PC 3, so that the level is the same. The gain of the microphone amplifier (PGA 122) is varied, and the value at the same input level is stored in the internal memory of the PGA 122 by the control command of the wireless device 1.

  According to the third embodiment, the speaker of the gain adjusting device is fixed for two voice microphones and ambient noise, and the movable part of the speaker is eliminated, so that the time required for resetting the speaker position is eliminated and the positioning accuracy is also improved. Can be improved.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Radio | wireless machine of 1st Embodiment, 11-1 ... Sound microphone, 11-2 ... Ambient noise microphone, 12 ... Stereo codec, 121, 122 ... Programmable gain amplifier (PGA), 123, 124 ... Analog / Digital converter (ADC), 13 Digital signal processor (DSP), 14 Digital / analog converter, 15 Orthogonal converter, 16 Power amplifier (PA), 17 Antenna, 18 Micro processing unit (MPU) DESCRIPTION OF SYMBOLS 1A ... Radio | wireless machine of 2nd Embodiment, 19 ... Serial data interface, 2 ... Level converter, 3 ... Personal computer (PC), 4 ... Oscillator, 5 ... Audio amplifier, 6 ... Microphone gain adjustment apparatus, 61-1 61-2. Speaker.

Claims (1)

A first microphone for collecting a voice and the ambient noise, the second microphone for collecting the ambient noise is attached to a position different from the first microphone, to the first channel of the first microphone is connected A first amplifier that amplifies the input, a first converter that digitally converts the output of the first amplifier, a second amplifier that amplifies the input to the second channel to which the second microphone is connected, and the output of the second amplifier A stereo codec including a second converter for digitally converting the first digital signal output from the stereo codec by the first converter and the second digital signal output from the stereo codec by software processing. A signal processing unit that cancels components and outputs only a voice signal, and an output signal from the signal processing unit is converted into a radio signal. A gain adjustment system for adjusting the gain of said first amplifier and said second amplifier in a radio apparatus and a transmission unit for signal for,
A set unit for setting the radio device in a predetermined state, and the same positional relationship with respect to the first microphone and the second microphone of the radio device in a state where the radio device is set in the set unit. A gain adjusting device comprising a first speaker and a second speaker arranged to be;
A sound generator connected to the first speaker and the second speaker, and for outputting an adjustment sound from the first speaker and the second speaker;
A computer connected to the wireless device via the set unit of the gain adjusting device and connected to the sound pressure adjusting unit;
Comprising
The computer
The sound generator is operated in a state where the wireless device is set in the set unit of the gain adjusting device, and the sound of the same sound pressure is output from the first speaker and the second speaker at different times. Means to
Means for capturing the first digital signal output from the stereo codec of the wireless device in a state where the sound is output only from the first speaker, and calculating and storing the amplitude value as a first amplitude value;
Means for capturing the second digital signal output from the stereo codec of the wireless device in a state where the sound is output only from the second speaker and calculating the amplitude value as a second amplitude value;
Means for comparing the calculated second amplitude value with the stored first amplitude value and adjusting the gain of the second amplifier so that the difference is within a predetermined value;
A gain adjustment system comprising:

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