CN207399447U - A kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings - Google Patents
A kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings Download PDFInfo
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- CN207399447U CN207399447U CN201721166599.1U CN201721166599U CN207399447U CN 207399447 U CN207399447 U CN 207399447U CN 201721166599 U CN201721166599 U CN 201721166599U CN 207399447 U CN207399447 U CN 207399447U
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Abstract
The utility model is related to Digital Signal Processing and audio signal processing techniques more particularly to a kind of microphone based on FPGA frequency domain filterings to normalize calibrator (-ter) unit.Including standard tuning fork, a target microphone, several microphones to be calibrated, sequentially connected prime amplification module, AD sampling modules, field programmable gate array (FPGA) and display screen.The system realizes the normalization calibration of different microphones, reduces production cost, on the premise of the original electronic component of microphone is not changed, effectively improves fidelity during audio recording, reduces the otherness between distinct device, reduce distorted signals to the greatest extent.
Description
Technical field
The utility model belongs to Digital Signal Processing and field of audio processing more particularly to based on FPGA and fast Fourier
The signal processing of conversion.
Background technology
With the development of stereo set and the popularization of high-fidelity headphone, requirement of the user to audio quality increasingly improves.Together
When, different microphone records more sensitive to recorder including acoustic signal processing methods such as speech recognition, spectrum analyses
It makes same section audio and also has very big difference.In order to reach improve audio recording when fidelity, reduce distinct device between
Otherness reduces the purpose of distorted signals to the greatest extent, and the way generally used is：The higher product parts of precision are replaced, use base
In the balanced device of experience or the expensive high-fidelity microphone of selection.But this method can make economic and time cost
It greatly improves.If common microphone can be normalized for calibration according to the frequency response characteristic of high-fidelity microphone, make it
Possess more like frequency response characteristic, just can fast and effeciently improve the recording quality of microphone.
Utility model content
The purpose of this utility model is to provide a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings.
It is in by target microphone (high-fidelity microphone) and microphone to be calibrated (common microphone) under same environment, altogether
With the section audio that reception standard sounding equipment (tuning fork) is sent, audio is handled via filtering and Fast Fourier Transform (FFT) (FFT)
Afterwards, relative correction is carried out according to frequency response characteristic, obtains a calibration curve.
To achieve the above object, the technical solution adopted in the utility model is：A kind of Mike based on FPGA frequency domain filterings
Wind normalizes calibrator (-ter) unit, including standard tuning fork, a target microphone, several microphones to be calibrated, sequentially connected prime
Amplification module, A/D sampling modules, field programmable gate array (FPGA) and display screen.
In the above-mentioned microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings, FPGA module uses main control chip
FPGA, main control chip FPGA are the EP4CE40F23C8 chips of ALTERA companies, and piece has been embedded in NIOS II embedded processings
Device.
In the above-mentioned microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings, standard tuning fork uses audible frequency
For the aluminium alloy tuning tuning fork of 440Hz.
In the above-mentioned microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings, target microphone is compared with treating
The high-fidelity microphone for microphone is calibrated, and to be user wish to improve the Mike of its frequency response characteristic microphone to be calibrated
Wind.
In the above-mentioned microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings, prime amplification module uses two-stage
Amplifier Cascaded amplification, the first order use the low-power precision instrument amplifier INA128 of TI companies, and it is 200 times to set gain；The
Two level uses the high-precision low noise operational amplifier OPA227 of TI companies, and it is 3 times to set gain, is connect using with mutually amplification
Method.
In the above-mentioned microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings, A/D sampling modules are public using TI
16 250KHz ADS8505 chips of department.
In the above-mentioned microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings, display screen is using MD070SD electricity
Resistive touch screen is driven by FPGA circuitry and shows Fast Fourier Transform (FFT) curve and calibration curve.
The beneficial effects of the utility model are：The normalization calibration of different microphones is realized, production cost is reduced, not
On the premise of changing the original electronic component of microphone, fidelity during audio recording is effectively improved, reduce between distinct device
Otherness reduces distorted signals to the greatest extent.
Description of the drawings
Fig. 1 is the structure diagram of one embodiment of the utility model；
Fig. 2 is the microphone pickup schematic diagram of one embodiment of the utility model；
Fig. 3 is the preamplifying circuit figure of one embodiment of the utility model；
Fig. 4 is the A/D conversion circuit figures of one embodiment of the utility model；
Fig. 5 is the audio volume control figure of one embodiment of the utility model；
Fig. 6 is the Fourier spectrum figure at the audio a certain moment of one embodiment of the utility model；
Fig. 7 is the normalization calibration graph of one embodiment of the utility model；
Fig. 8 is audio volume control figure after the calibration of one embodiment of the utility model.
Specific embodiment
The embodiment of the utility model is described in detail below in conjunction with the accompanying drawings.
The example of the embodiment is shown in the drawings, wherein same or similar label represents identical or class from beginning to end
As element or there is same or like element.The embodiments described below with reference to the accompanying drawings are exemplary, only
For explaining the utility model, and the limitation to the utility model cannot be construed to.
Following disclosure provides many different embodiments or example is used for realizing the different structure of the utility model.For
The disclosure of simplified the utility model, is hereinafter described the component and setting of specific examples.They are merely examples, and
And purpose does not lie in limitation the utility model.In addition, the utility model can in different examples repeat reference numerals and/or word
It is female.This repetition is for purposes of simplicity and clarity, between itself not indicating discussed various embodiments and/or setting
Relation.In addition, the utility model provides the example of various specific techniques and material, but those of ordinary skill in the art can
To recognize the use of the applicability of other techniques and/or other materials.In addition, fisrt feature described below is special second
Levy it " on " structure can be formed as the embodiment contacted directly including the first and second features, other spy can also be included
Sign is formed in the embodiment between the first and second features, and such first and second feature may not be to contact directly.
, it is necessary to which explanation, unless otherwise prescribed and limits, term " connected " " connection " should in the description of the utility model
It is interpreted broadly, for example, it may be the connection inside mechanical connection or electrical connection or two elements, can be direct
It is connected, can also be indirectly connected by intermediary, it, can be according to specific feelings for those of ordinary skill in the related art
Condition understands the concrete meaning of above-mentioned term.
The technical solution that this example uses is as follows：A kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings,
Including standard tuning fork, a target microphone, several microphones to be calibrated, sequentially connected prime amplification module, A/D sampling moulds
Block, field programmable gate array (FPGA) and display screen.
Further, it is ALTERA companies that FPGA module, which uses main control chip FPGA, main control chip FPGA,
EP4CE40F23C8 chips, piece have been embedded in NIOS II embeded processors.When it carries out fast Fourier transformation operation,
It is 1024 to set its FFT window size, data precision 12, twiddle factor precision 12.
Further, standard tuning fork uses aluminium alloy tuning tuning fork of the audible frequency for 440Hz.
Further, target microphone uses Sen Haisaier MK4 microphones, possesses good high frequency individual features, to be calibrated
For microphone using three SM-8B-S microphones of winning victory, high frequency response is not good enough, and sensitivity is relatively low, to be improved.
Further, prime amplification module uses two stage amplifer Cascaded amplification, and the first order is accurate using the low-power of TI companies
Instrument amplifier INA128, it is 200 times to set gain；The second level uses the high-precision low noise operational amplifier of TI companies
OPA227, it is 3 times to set gain, amplifies connection using with phase.
Further, A/D sampling modules use 16 250KHz ADS8505 chips of TI companies.
Further, display screen uses MD070SD resistive touch screens, is driven by FPGA circuitry and shows Fast Fourier Transform (FFT)
Curve and calibration curve.
During specific implementation：
As shown in Fig. 2, target microphone and microphone circle to be calibrated are looped around standard pronunciation fork surrounding so that Mei Yimai
Gram wind is to tuning fork apart from equal, and each microphone is connected with the first order of prime amplification module, and the second level of prime amplification module is defeated
Outlet is connected with A/D modular converter input terminals, and A/D modular converters are connected with FPGA module, and FPGA module is connected with display screen.Order
After audio is received by microphone, prime amplification module is transmitted to by the single core cable for carrying outsourcing shielding for tuning fork sounding.
As shown in figure 3, prime amplification module is used to be amplified the small-signal of microphone records.
As shown in figure 4, A/D modules are used for the analog signal sampling generation digital signal of microphone input.
Display screen is used to show tonic train Fast Fourier Transform (FFT) result and normalization calibration curve.
It is ALTERA companies that the present embodiment FPGA module, which uses main control chip FPGA, main control chip FPGA,
EP4CE40F23C8 chips, piece have been embedded in NIOS II embeded processors, can realize complicated algorithm.This equipment passes through
FPGA realizes the control to A/D modules, the control to display screen, data processing, digital filter such as build at the functions.
As shown in figure 5, target microphone and the sound waveform of the microphone records to be calibrated shown in figure below shown in upper figure
There is very big difference, illustrate that microphone to be calibrated generates more considerable distortion phenomenon in recording process.
The tonic train for making target microphone records is St, audio to be calibrated is S1, S2,S3.The thick of audio is carried out by algorithm
Alignment, then with the digital phase-locked loop of FPGA, by the phase alignment of several section audio sequences, the precision calibrated with increase.
Fast Fourier Transform is carried out by FPGA logarithms section audio.The size of FFT windows is set for 1024, data from
On the frequency domain of time domain conversion, the transformation results F of target microphone records sequence is obtainedt<F, t>With microphone records sequence to be calibrated
The transformation results F of rown<F, t>(n=1,2,3).
The fundamental tone and harmonic series sent by tuning fork has fixed frequency, and on fourier spectrum, they are in the form of peak
Occur, frequency characteristic is relatively stable, small by noise jamming, can be as the reference of calibration convenient for calculating and observing, therefore claims it
It is characterized peak.
As shown in fig. 6, by FPGA to the FFT sequences F of each microphone to be calibratedn<F, t>(n=1,2,3) and mesh
Cursor microphone FFT sequences Ft<F, t>It is retrieved, finds these fundamental tones and the corresponding characteristic peak of harmonic series successively.
By the fundamental tone characteristic peak P of target microphonet0With each harmonic series characteristic peak Pt1, Pt2... the ratio between formula (1) value
As a standard, and the fundamental tone characteristic peak P of each microphone to be calibrated is obtainedi0(i=1,2,3) is special with harmonic series
Levy peak PijThe value of the ratio between (i=1,2,3, j=1,2,3 ...) formula (2), wherein i is the sequence number of microphone to be calibrated, and j is overtone
The sequence number of row characteristic peak.
As shown in fig. 7, it is α to make calibration factorij,
It, all can be according to the α acquired so to each microphone i to be calibratedijOne calibration curve of generation is exported to display
Screen.The calibration curve of generation is a digital filter, using the wave filter to the audios of former microphone records to be calibrated into
Row optimization.
As shown in figure 8, the audio volume control by optimization has larger improvement compared with original waveform, with target microphone records
Waveform have very high similarity.
In the present embodiment actual test, select 1002 60MHz digital oscilloscopes of Tektronix TDS and equipment itself aobvious
Display screen is observed and tested.In actual test after normalizing calibration process, microphone to be calibrated is in 20Hz-20kHz frequencies
Domain maximum distortion ratio is (with the voltage magnitude of a certain frequency of microphone to be calibrated and the voltage magnitude of standard microphone respective frequencies
The ratio between calculating) by 72.0% drop to 17.8%.
It should be appreciated that this specification do not elaborate partly belong to the prior art.
Although above in association with having illustrated specific embodiment of the present utility model, those of ordinary skill in the art
It should be appreciated that these are merely examples, various deformation or modification can be made to these embodiments, without departing from this practicality
New principle and essence.The scope of the utility model is only limited by the claims that follow.
Claims (7)
1. it is a kind of based on FPGA frequency domain filterings microphone normalization calibrator (-ter) unit, which is characterized in that including standard tuning fork, one
Target microphone, several microphones to be calibrated, sequentially connected prime amplification module, AD sampling modules, field-programmable gate array
Row and display screen.
2. a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings as described in claim 1, which is characterized in that
It is the EP4CE40F23C8 chips of ALTERA companies that FPGA module, which uses main control chip FPGA, main control chip FPGA, and piece is embedded in
NIOS II embeded processors.
3. a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings as described in claim 1, which is characterized in that
Standard tuning fork uses aluminium alloy tuning tuning fork of the audible frequency for 440Hz.
4. a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings as described in claim 1, which is characterized in that
Target microphone is the high-fidelity microphone for microphone to be calibrated, and microphone to be calibrated is user wishes to improve
The microphone of its frequency response characteristic.
5. a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings as described in claim 1, which is characterized in that
Prime amplification module uses two stage amplifer Cascaded amplification, and the first order uses the low-power precision instrument amplifier of TI companies
INA128, it is 200 times to set gain；The second level uses the high-precision low noise operational amplifier OPA227 of TI companies, sets and increases
Benefit is 3 times, amplifies connection using with phase.
6. a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings as described in claim 1, which is characterized in that
AD sampling modules use 16 250KHz ADS8505 chips of TI companies.
7. a kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings as described in claim 1, which is characterized in that
Display screen uses MD070SD resistive touch screens, is driven by FPGA circuitry and shows Fast Fourier Transform (FFT) curve and calibration curve.
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| CN201721166599.1U CN207399447U (en) | 2017-09-11 | 2017-09-11 | A kind of microphone normalization calibrator (-ter) unit based on FPGA frequency domain filterings |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111343562A (en) * | 2020-03-31 | 2020-06-26 | 郑州工程技术学院 | Music audio signal calibration system |
| CN111602415A (en) * | 2019-04-24 | 2020-08-28 | 深圳市大疆创新科技有限公司 | Signal processing method and device for pickup equipment and computer storage medium |
| CN112180196A (en) * | 2020-09-30 | 2021-01-05 | 重庆市海普软件产业有限公司 | State detection feedback system and method of intelligent equipment |
-
2017
- 2017-09-11 CN CN201721166599.1U patent/CN207399447U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111602415A (en) * | 2019-04-24 | 2020-08-28 | 深圳市大疆创新科技有限公司 | Signal processing method and device for pickup equipment and computer storage medium |
| WO2020215239A1 (en) * | 2019-04-24 | 2020-10-29 | 深圳市大疆创新科技有限公司 | Signal processing method and device for sound pickup apparatus, and computer storage medium |
| CN111343562A (en) * | 2020-03-31 | 2020-06-26 | 郑州工程技术学院 | Music audio signal calibration system |
| CN111343562B (en) * | 2020-03-31 | 2021-09-10 | 郑州工程技术学院 | Music audio signal calibration system |
| CN112180196A (en) * | 2020-09-30 | 2021-01-05 | 重庆市海普软件产业有限公司 | State detection feedback system and method of intelligent equipment |
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Granted publication date: 20180522 Termination date: 20180911 |