CN205249484U

CN205249484U - Microphone linear array reinforcing directive property adapter

Info

Publication number: CN205249484U
Application number: CN201521118423.XU
Authority: CN
Inventors: 葛冉; 陈景东; 俞波
Original assignee: Linjing Acoustics Technology Jiangsu Co Ltd
Current assignee: Linjing Acoustics Technology Jiangsu Co Ltd
Priority date: 2015-12-30
Filing date: 2015-12-30
Publication date: 2016-05-18
Anticipated expiration: 2025-12-30

Abstract

The utility model relates to a microphone linear array reinforcing directive property adapter has the linear array adapter of 8 electret miaow heads, is applied to prison recording control, the security protection control of the procuratorial, judicial and public security organ that the turnkey waits. Rely on 8 electret miaow head line array, the interact of the small time difference between every miaow head in the array is arrived through the sound wave to specific design that sound hole syntropy was arranged, forms the controllable directive property of algorithm. Utilize miaow head linear array to have the inhibit feature very strong to the far field interference noise, have good signal acquisition nature under the noise environment, improve the acoustic effect of adapter. Reduction that built -in denoising algorithm is very big the noise that leads to of factors such as environment, circuit. The critical area's of procuratorial, judicial and public security organ that the turnkey waits high quality pronunciation control can be satisfied, the full record of speech information to emergency is realized to reliable traceing back afterwards. The control of reliable pronunciation is to the public security of installation region, anti -terrorism, explosion -proof etc. Significant.

Description

The linear array of a kind of microphone strengthens directive property sound pick-up

Technical field:

The utility model relates to protection and monitor field, relates in particular to the linear array of a kind of microphone and strengthens directive property sound pick-up.

Background technology:

Traditional security protection sound pick-up generally comprises an omnidirectional or the heart-shaped electret microphone pointing to, and electret microphone is realized the conversion of audio signal to the signal of telecommunication, then amplifies simulation output after low pass or bandpass filtering by one-level or two-stage analog circuit.

Also there are on the market some sound pick-ups to comprise two electret microphones, an electret microphone remolding sensitivity is higher, be responsible for the pickup in free far field, another one electret microphone remolding sensitivity is lower, be responsible for the pickup of near field ambient noise, then by analog circuit control phase, stack carrys out Background suppression noise in the same way.

These pick up peace antiphone and have following defect:

(1) in actual applications, there is larger ambient noise in surrounding environment, can not effectively reduce the noise of whole frequency range by the method for simulation noise reduction, even, by the HFS loss of sound, causes the signal quality of output not high.

(2) because the electret microphone fidelity of selecting is lower, adding the phase delay that filter circuit causes, there is difference in voice signal and the actual sound of output. Can not meet the requirement of security protection voice monitoring definition.

(3) pickup scope is less, depends on the sensitivity of electret microphone completely, generally can only accomplish the pickup within the scope of 10m. Electret microphone is along with the increase of service time, and sensitivity meeting decays and reduces pickup distance. Due to the restriction of pickup scope, sound pick-up is generally hung in ceiling centre position, room, and source of sound is pointed in sound hole, near key area. And camera overlay area is larger, be arranged on one jiao, top, room, sound pick-up and camera are distant, and wiring is comparatively complicated.

(4) function ratio is more single, only has pickup and the amplification of audio frequency, is difficult to realize some specific function application, such as ambient noise inhibition, beam forming and beam direction etc.

Utility model content:

In order to address the above problem, the utility model provides and has utilized the linear array enhancing of microphone technology, provides a kind of and gathers that sound articulation is high, excellent noise reduction effect, pickup distance, has the technical scheme of the sound pick-up of directive property:

The linear array of a kind of microphone strengthens directive property sound pick-up, comprise microphone array column unit, audio coding unit, DSP processing unit and audio output unit, microphone array column unit and audio coding unit conducting, audio coding unit is connected with DSP processing unit with parallel mode with audio output unit.

As preferably, microphone array column unit comprises 4 MEMS miaow heads, and 4 MEMS miaow heads straight line on circuit board is arranged and formed the linear array of microphone, and the centre-to-centre spacing of adjacent MEMS miaow head is 20 ± 0.1mm.

As preferably, the sensitivity of MEMS miaow head is-40dB ± 0.5dB, and frequency response is 100Hz – 10KHz, and length is 3.76mm, and width is 2.95mm, and signal to noise ratio is not less than 60dB.

As preferably, audio decoding unit adopts integrated IC chip NAU85L40, and NAU85L40 is maximum supports 48KHz sampling, and system adopts 16KHz sample rate, 24bit sampling precision.

The beneficial effects of the utility model are:

(1) the utility model utilizes the directive property sound pick-up that the linear array enhancing of microphone technology realizes, forming at Difference Beam is the constant beamforming algorithm of frequency, voice signal after reconstruction is unchanged in the region frequency content of people's ear sensitivity, so the voice signal definition after rebuilding is high, can meet the high-quality speech monitoring needs of some key areas.

(2) in the utility model, 4 of sound pick-up microphones superpose to audio signal in the same way, and directive property is good, pickup distance, and effectively pickup distance can reach more than 20 meters.

(3) utility model, compared with single simulation sound pick-up, due to the digitlization of voice signal of the linear array received of microphone, can be further processed, and can also carry out sound source separation, separate the specific function application such as reverberation and auditory localization and sound-source follow-up.

(4) in utility model, sound pick-up removes the synchronous recording that can use traditional analog audio interface and camera cooperation to realize audio frequency and video, can also use USB digital audio interface, the circuit noise that USB digital audio interface avoids camera AD or Codec chip double sampling to bring, the signal to noise ratio of raising shooting head end audio signal.

Brief description of the drawings:

Fig. 1 is structural representation of the present utility model;

Fig. 2 is microphone array cellular construction schematic diagram;

Fig. 3 is the desirable beam pattern of microphone;

Fig. 4 is miaow head beam pattern of the present utility model.

Detailed description of the invention:

For making goal of the invention of the present utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing, embodiment of the present utility model is described in further detail.

As shown in Figure 1, the utility model has designed the linear array of a kind of microphone and has strengthened directive property sound pick-up, comprise microphone array column unit 1, audio coding unit 2, DSP processing unit 3 and audio output unit 4, microphone array column unit 1 and audio coding unit 2 conductings, audio coding unit 2 is connected with DSP processing unit 3 with parallel mode with audio output unit 4. Microphone array column unit 1 is higher to the coherence request of microphone sensitivity, require sensitivity variations to be no more than 1dB, and the general Mi Tou manufacturer standard of dispatching from the factory is ± 3dB or ± 1dB, this programme is selected the miaow head uniformity of producer's supply of material, selects sensitivity variations and is no more than being assembled on a circuit board of 1dB. Effect after miaow head sensitivity variations comparison conference affects wave beam and forms, causes directive property deviation.

Microphone array column unit 1 wherein as shown in Figure 2, comprises that 5,4 MEMS miaow heads 5 of 4 MEMS miaow heads straight line on circuit board 6 is arranged to form the linear array of microphone, and the centre-to-centre spacing of adjacent MEMS miaow head 6 is 20 ± 0.1mm. And the sensitivity of MEMS miaow head 6 is-40dB ± 0.5dB, frequency response is 100Hz – 10KHz, and length is 3.76mm, and width is 2.95mm, and signal to noise ratio is not less than 60dB.

Audio decoding unit 2 adopts integrated IC chip NAU85L40, the maximum 48KHz of support of NAU85L40 samples, system adopts 16KHz sample rate, 24bit sampling precision, first audio signal amplifies by PGA, is then input to AD and carries out analog-to-digital conversion, ALC link realizes PGA and adjusts with audio input signal intensity Gain Automaticly, ALC can follow the tracks of, monitor the audio signal level of PGA output at any time, and in the time that input signal increases, alc circuit reduces the gain of PGA automatically; In the time that input signal reduces, alc circuit increases the gain of PGA automatically, so that the signal collecting remains on optimizing level. NAU85L40 is by the McASP0 interface docking of TDM bus and DSP, and the audio signal of 4 passages is input to DSP by time-multiplexed mode.

DSP processing unit 3 is cores of whole sound pick-up, first DSP receives the data of TDM bus in dMAX mode, then the signal frame that the signal segmentation according to 1/4 overlapping rate, 4 microphones in array being received becomes to overlap each other, then utilizes the Short Time Fourier Transform of 256 that the data of these signal frames are changed and change to frequency domain from time domain. On the subband of each Short Time Fourier Transform, design a Difference Beam, the filter factor that wherein Difference Beam forms obtains by solving by the system of linear equations retraining zero point in advance. The Difference Beam shaper that utilization designs is carried out filtering to the Short Time Fourier Transform coefficient of 4 microphones, to reach the object of eliminating noise and estimate desired signal on subband. Finally, utilize overlap-add summation, then by the Fourier inversion in short-term of 256, the signal of estimation is transformed into time domain, obtain the voice signal after rebuilding.

The microphone that the linear array of microphone adopts is omni-directional miaow head, and 360 ° of pickup effects are identical, and desirable beam pattern is equivalent to circle, as shown in Figure 3. Obtain Difference Beam the efficiency of formation by designing different constraints, and then control 4 microphones and can superpose in the same way in a certain desired orientation, sound pick-up is upwards strengthened the party, and to producing less response in other direction, form directive property sound pick-up. This programme adopts the heart-shaped design of pointing to, and beam pattern as shown in Figure 4.

Voice signal after reconstruction sends to the McASP1 interface of DSP equally by dMAX mode. Audio output unit connects the McASP1 interface of DSP by IIS bus, be driven into two-way IIS bus by IISBusBuffer, and IIS1 bus connects the output of DA audio frequency simulation, and IIS2 bus connects the output of USB voice data.

First DA is converted to analog signal by audio digital signals, then output to the long line driver element of OPA, the long line driver element of OPA amplifies analog signal, and realizes the non-equilibrium output of 600Ohms, and the long line driver element of OPA connects the output of RCA jack and the output of 3.5mm earphone jack simultaneously. Sound pick-up provides two kinds of jack connected modes, to meet the on-the-spot different wiring demand of safety monitoring. The output of USB voice data adopts integration USB toIISBridge chip CP2114 to receive IIS bus data, converts USB bag to, realizes the USB asynchronous transmission of audio signal. In this programme, sound pick-up is invented to PC standard USB sound card, utilize such as AdobeAudition of standard recording software etc. to record, realize the Digital Transmission of audio signal.

The directive property sound pick-up that the utility model utilizes the linear array enhancing of microphone technology to realize, has the following advantages:

(1) Difference Beam formation is the constant beamforming algorithm of frequency, and the voice signal after reconstruction is unchanged in the region frequency content of people's ear sensitivity, so the voice signal definition after rebuilding is high, can meet the high-quality speech monitoring needs of some key areas.

(2) 4 of sound pick-up microphones superpose to audio signal in the same way, and directive property is good, pickup distance, and effectively pickup distance can reach more than 20 meters.

(3) compared with single simulation sound pick-up, due to the digitlization of voice signal of the linear array received of microphone, can be further processed, can also carry out sound source separation, separate the specific function application such as reverberation and auditory localization and sound-source follow-up.

(4) sound pick-up is except using traditional analog audio interface and camera to coordinate the synchronous recording of realizing audio frequency and video, can also use USB digital audio interface, the circuit noise that USB digital audio interface avoids camera AD or Codec chip double sampling to bring, the signal to noise ratio of raising shooting head end audio signal.

Above-described embodiment is preferred embodiment of the present utility model; it is not the restriction to technical solutions of the utility model; as long as the technical scheme that can realize on the basis of above-described embodiment without creative work, all should be considered as falling within the scope of the rights protection of the utility model patent.

Claims

1. the linear array of microphone strengthens directive property sound pick-up, it is characterized in that: comprise microphone array column unit, audio coding unit, DSP processing unit and audio output unit, described microphone array column unit and audio coding unit conducting, described audio coding unit is connected with DSP processing unit with parallel mode with audio output unit.

2. the linear array of a kind of microphone according to claim 1 strengthens directive property sound pick-up, it is characterized in that: described microphone array column unit comprises 4 MEMS miaow heads, 4 MEMS miaow heads straight line on circuit board is arranged and is formed the linear array of microphone, and the centre-to-centre spacing of adjacent MEMS miaow head is 20 ± 0.1mm.

3. the linear array of a kind of microphone according to claim 2 strengthens directive property sound pick-up, it is characterized in that: the sensitivity of described MEMS miaow head is-40dB ± 0.5dB, and frequency response is 100Hz – 10KHz, and length is 3.76mm, width is 2.95mm, and signal to noise ratio is not less than 60dB.

4. the linear array of a kind of microphone according to claim 1 strengthens directive property sound pick-up, it is characterized in that: described audio decoding unit adopts integrated IC chip NAU85L40, maximum 48KHz sampling, system employing 16KHz sample rate, the 24bit sampling precision supported of described NAU85L40.