CN103308153A - Environmental noise variable-excitation amplitude modulation and frequency modulation detecting and estimating method - Google Patents

Abstract

The invention provides an environmental noise variable-excitation amplitude modulation and frequency modulation detecting and estimating method in order to overcome the technical defect that different types of noise sensors are needed for different environmental noises and to solve the magnetic saturation problem. The method has the advantages that by a common excitation mode of winding a coil on a soft magnetic core prior to powering on, size and direction of electric excitation of the coil are controlled by means of PWM (pulse width modulation) so as to form magnetic fields and hysteresis loops in different intensities, so that frequency and amplitude of received acoustical signalsare changed, and detection range of a sensor is enlarged; detected signals are subjected to frequency reduction, then noise intensity is computed, and the problem that existing moving-coil noise sensors require different types and magnetic saturation for different environmental noises is solved.

Description

Neighbourhood noise variable excitation amplitude modulationfrequency modulation detects and method of estimation

Technical field

The present invention relates to the environmental noise measurement technical field, particularly neighbourhood noise variable excitation amplitude modulationfrequency modulation detects and method of estimation.

Background technology

Along with the development of modern urban construction and urban transportation, urban environment noise pollutes has become the important environmental problem that the big city, countries in the world faces; Noise pollution has become the fourth-largest environmental hazard after water pollution, atmospheric pollution, solid waste pollution; City noise pollution has had a strong impact on people and has worked normally, learns and have a rest, noise pollution complaint event number occupies the first place that events are complained in all kinds of environmental pollutions always, and the detection that neighbourhood noise is carried out promptly and accurately just seems particularly important with analysis and effective control.

The sensor of detection noise can be divided into the noise transducers such as electrodynamic type (moving-coil type), condenser type, piezoelectric type by its transduction principle at present; Moving-coil microphone mainly is made of vibrating diaphragm, voice coil loudspeaker voice coil, permanent magnet and step-up transformer etc.; Its principle of work is diaphragm along with vibration before and after the sound, thereby drives the voice coil loudspeaker voice coil that links to each other with diaphragm is made cutting magnetic line in magnetic field motion, according to electromagnetic induction principle, will produce at the coil two ends and to respond to the audio-frequency electric kinetic potential, thereby finish the acoustic-electric conversion; Condenser microphone is a kind ofly to utilize the electric capacity conversion and cause the microphone of acoustic-electric transformation; The variable condenser that spacing is very little that it is comprised of a vibrating diaphragm and fixed electorde; When diaphragm produced vibration under sound wave effect, the distance between vibrating diaphragm and fixed electorde just changed, and causes the variation of electric capacity; If at the two ends of electric capacity a pull-up resistor R and dc polarization voltage E are arranged, when then electric capacity changes with sound wave, will produce the audio voltage of alternation at the two ends of R; Piezoelectric microphone is to finish the acoustic-electric conversion by the piezoelectric crystal with piezoelectric effect, and it makes the crystal cut both sides produce the charges of different polarity that electric weight equates by acoustic pressure, forms potential difference (PD), belongs to Conversion of Energy type sensor.

Patent " Wu Zonghan. moving magnet planar coil type microphone [P]. China: CN 201571198 U " a kind of moving magnet planar coil type microphone disclosed, comprise spiral planar coil and magnetic film, and the spiral planar coil is faced mutually with magnetic film, is provided with the gap between spiral planar coil and magnetic film; This utility model has adopted and has allowed original motionless magnet become movably, and with acoustic pressure effect campaign, so changed again the structure that moving-coil links to each other with vibrating membrane (sound film) in the moving coil microphone, the moving-coil of this utility model changes the planar coil that the mode of spiral planar alignment is made into by general screwed pipe shape.

Moving-coil type noise transducer detection noise all is by vibrating diaphragm induction acoustic pressure size at present, the magnetic field that produces by permanent magnet induces electrodynamic type, above-mentioned patent " moving magnet planar coil type microphone " is although change vibrating diaphragm into and be with magnetic vibrating diaphragm, simplified the structure of microphone, but the magnetic field that magnet produces is uncontrollable, can't regulate magnetic field intensity according to actual conditions; Because the noise size has randomness; sometimes the acoustic pressure of noise exceeds the sensing range of this sensor, needs the noise transducer of different ranges and sensitivity to come detection noise, has increased testing cost; particularly this sensor often can occur saturatedly, utters long and high-pitched sounds as occurring after amplifying.

Summary of the invention

Need dissimilar noise transducer and magnetic saturation problem and technological deficiency in the varying environment noise in order to overcome, the invention provides a kind of neighbourhood noise variable excitation amplitude modulationfrequency modulation detects and method of estimation, the common excitation mode that the method powers up by coiling on soft magnet core again, use width modulation (PWM) to come the size and Orientation of control coil electric power excitation, to form magnetic field and the magnetic hysteresis loop of varying strength, thereby change the acoustical signal frequency and the amplitude that receive, enlarge the sensing range of sensor; Then detected signal is carried out the frequency reduction, again noise intensity is calculated, solved existing moving-coil type noise transducer to needing different model and magnetic saturation problem in the varying environment noise.

The technical solution adopted for the present invention to solve the technical problems: a kind of neighbourhood noise variable excitation amplitude modulationfrequency modulation detects and method of estimation, and its characteristics are as follows:

Permanent magnet core in the moving-coil microphone that (1) will be made of vibrating diaphragm, voice coil loudspeaker voice coil, permanent magnet core and step-up transformer improves and becomes soft magnet core, but on soft magnet core coiling and the common excitation of soft magnet core; The controlled excitation mode of intensity of excitation size, direction, magnetic hysteresis loop; Schematic construction is referring to Fig. 1;

(2) control the DC current size and Orientation of coil on the soft magnet core with PWM, form magnetic field and the magnetic hysteresis loop of varying strength, thereby change acoustical signal frequency and the amplitude that receives, enlarge the sensing range of sensor;

(3) by applying different PWM to coil on the soft magnet core, the analog audio signal of given frequency is tested, is obtained following formula by data fitting:

$y_{\mathrm{\ω}}\left(t\right)\≈\left\{\begin{array}{cc}{g}_{\mathrm{\ω}}{\tan }^{-1}[m_{\mathrm{\ω}}\sin \left(\mathrm{\ωt}\right)+k_{1\mathrm{\ω}}]& \sin \left(\mathrm{\ωt}\right)>0\\ g_{\mathrm{\ω}}{\tan }^{-1}[m_{\mathrm{\ω}}\sin \left(\mathrm{\ωt}\right)-k_{2\mathrm{\ω}}]& \sin \left(\mathrm{\ωt}\right)\≤0\end{array}\right.$

In the formula: m _ωBe the analog audio signal amplitude of given frequencies omega, m _ωSin (ω t) is the analog audio signal, and t is the time, y _ω(t) be at analog audio signal m _ωThe output signal that obtains during sin (ω t), g _ωBe output amplitude coefficient, k _{1 ω}And k _{2 ω}Be the magnetic hysteresis loop coefficient;

(4) gather the rear moving-coil microphone output signal of improvement by A/D, and according to following equation signal carried out frequency and amplitude demodulation:

$a\left(\mathrm{ik\ωT}\right)\≈\left\{\begin{array}{cc}{k}_{1\mathrm{\ω}}-\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}}& a\left(\mathrm{ik\ωT}\right)>0\\ -(k_{2\mathrm{\ω}}+\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}})& a\left(\mathrm{ik\ωT}\right)\≤0\end{array}\right.$

In the formula: T is the sampling period of A/D, i=1, and 2 ..., n, nT are the current sampling time, ω is the basic frequency of signal,

$a\left(\mathrm{ik\ωT}\right)=\underset{k=1}{\overset{N}{\mathrm{\Σ}}}[m_{\mathrm{\ωk}}\sin \left(\mathrm{ik\ωT}\right)+p_{\mathrm{\ωk}}\cos \left(\mathrm{ik\ωT}\right)],k=\mathrm{1,2},...N,$ N is the high reps of dust series expansion item in Fu, m _{ω k}, p _{ω k}Coefficient for dust series expansion item in Fu;

(5) definition:

$a\left(\mathrm{ik\ωT}\right)=\left\{\begin{array}{cc}{k}_{1\mathrm{\ω}}-\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}}+v\left(i\right)& a\left(\mathrm{ik\ωT}\right)>0\\ -(k_{2\mathrm{\ω}}+\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}})+v\left(i\right)& a\left(\mathrm{ik\ωT}\right)\≤0\end{array}\right.$

In the formula: v (i) is plant noise, i=1, and 2 ..., n; If supposition v (i) is the zero-mean white Gaussian noise, can directly adopt method for parameter estimation to estimate the Coefficient m of dust series expansion item in Fu _{ω k}, p _{ω k}And ω; After obtaining a (ik ω T) sequence, can directly obtain the power spectrum of noise intensity.

The invention has the beneficial effects as follows: the common excitation mode that powers up again by coiling on soft magnet core, come the size and Orientation of control coil electric power excitation with width modulation, to form magnetic field and the magnetic hysteresis loop of varying strength, thereby change the acoustical signal frequency and the amplitude that receive, enlarge the sensing range of sensor; Then detected signal is carried out the frequency reduction, again noise intensity is calculated, solved existing moving-coil type noise transducer to needing different model and magnetic saturation problem in the varying environment noise.

Below in conjunction with drawings and Examples the present invention is elaborated.

Description of drawings

Fig. 1 is variable excitation noise transducer structural representation of the present invention.

Embodiment

With reference to Fig. 1.

Permanent magnet core in the moving-coil microphone that (1) will be made of vibrating diaphragm, voice coil loudspeaker voice coil, permanent magnet core and step-up transformer improves and becomes the spinel-type soft magnet core, but on soft magnet core coiling and the common excitation of soft magnet core; The controlled excitation mode of intensity of excitation size, direction, magnetic hysteresis loop;

(2) export the DC current size and Orientation that the PWM waveform is controlled coil on the spinel-type soft magnet core by DSP2407, form magnetic field and the magnetic hysteresis loop of varying strength, thereby change acoustical signal frequency and the amplitude that receives, enlarge the sensing range of sensor;

(3) by applying different PWM to coil on the soft magnet core, the analog audio signal of given frequency is tested, is obtained following formula by data fitting:

$y_{\mathrm{\ω}}\left(t\right)\≈\left\{\begin{array}{cc}{g}_{\mathrm{\ω}}{\tan }^{-1}[m_{\mathrm{\ω}}\sin \left(\mathrm{\ωt}\right)+k_{1\mathrm{\ω}}]& \sin \left(\mathrm{\ωt}\right)>0\\ g_{\mathrm{\ω}}{\tan }^{-1}[m_{\mathrm{\ω}}\sin \left(\mathrm{\ωt}\right)-k_{2\mathrm{\ω}}]& \sin \left(\mathrm{\ωt}\right)\≤0\end{array}\right.$

In the formula: m _ωBe the analog audio signal amplitude of given frequencies omega, m _ωSin (ω t) is the analog audio signal, and t is the time, y _ω(t) be at analog audio signal m _ωThe output signal that obtains during sin (ω t), g _ωBe output amplitude coefficient, k _{1 ω}And k _{2 ω}Be the magnetic hysteresis loop coefficient;

(4) gather the rear moving-coil microphone output signal of improvement by A/D chip AD7655, and according to following equation signal carried out frequency and amplitude demodulation:

$a\left(\mathrm{ik\ωT}\right)\≈\left\{\begin{array}{cc}{k}_{1\mathrm{\ω}}-\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}}& a\left(\mathrm{ik\ωT}\right)>0\\ -(k_{2\mathrm{\ω}}+\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}})& a\left(\mathrm{ik\ωT}\right)\≤0\end{array}\right.$

In the formula: T is the sampling period of A/D, i=1, and 2 ..., n, nT are the current sampling time, ω is the basic frequency of signal,

$a\left(\mathrm{ik\ωT}\right)=\underset{k=1}{\overset{N}{\mathrm{\Σ}}}[m_{\mathrm{\ωk}}\sin \left(\mathrm{ik\ωT}\right)+p_{\mathrm{\ωk}}\cos \left(\mathrm{ik\ωT}\right)],k=\mathrm{1,2},...N,$ N is the high reps of dust series expansion item in Fu, m _{ω k}, p _{ω k}Coefficient for dust series expansion item in Fu;

(5) definition:

$a\left(\mathrm{ik\ωT}\right)=\left\{\begin{array}{cc}{k}_{1\mathrm{\ω}}-\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}}+v\left(i\right)& a\left(\mathrm{ik\ωT}\right)>0\\ -(k_{2\mathrm{\ω}}+\tan \frac{y_{\mathrm{\ω}}\left(\mathrm{iT}\right)}{g_{\mathrm{\ω}}})+v\left(i\right)& a\left(\mathrm{ik\ωT}\right)\≤0\end{array}\right.$

In the formula: v (i) is plant noise, i=1, and 2 ..., n; If supposition v (i) is the zero-mean white Gaussian noise, can directly adopt method for parameter estimation to estimate the Coefficient m of dust series expansion item in Fu _{ω k}, p _{ω k}And ω; After obtaining a (ik ω T) sequence, can directly obtain the power spectrum of noise intensity.

Claims (1)

1. a neighbourhood noise variable excitation amplitude modulationfrequency modulation detects and method of estimation, and its characteristics are as follows:

Permanent magnet core in the moving-coil microphone that (1) will be made of vibrating diaphragm, voice coil loudspeaker voice coil, permanent magnet core and step-up transformer improves and becomes soft magnet core, but on soft magnet core coiling and the common excitation of soft magnet core; The controlled excitation mode of intensity of excitation size, direction, magnetic hysteresis loop; Schematic construction is referring to Fig. 1;

(2) control the DC current size and Orientation of coil on the soft magnet core with PWM, form magnetic field and the magnetic hysteresis loop of varying strength, thereby change acoustical signal frequency and the amplitude that receives, enlarge the sensing range of sensor;

(3) by applying different PWM to coil on the soft magnet core, the analog audio signal of given frequency is tested, is obtained following formula by data fitting:

In the formula: m _ωBe the analog audio signal amplitude of given frequencies omega, m _ωSin (ω t) is the analog audio signal, and t is the time, y _ω(t) be at analog audio signal m _ωThe output signal that obtains during sin (ω t), g _ωBe output amplitude coefficient, k _{1 ω}And k _{2 ω}Be the magnetic hysteresis loop coefficient;

(4) gather the rear moving-coil microphone output signal of improvement by A/D, and according to following equation signal carried out frequency and amplitude demodulation:

In the formula: T is the sampling period of A/D, i=1, and 2 ..., n, nT are the current sampling time, ω is the basic frequency of signal,

N is the high reps of dust series expansion item in Fu, m _{ω k}, p _{ω k}Coefficient for dust series expansion item in Fu;

(5) definition:

In the formula: v (i) is plant noise, i=1, and 2 ..., n; If supposition v (i) is the zero-mean white Gaussian noise, can directly adopt method for parameter estimation to estimate the Coefficient m of dust series expansion item in Fu _{ω k}, p _{ω k}And ω; After obtaining a (ik ω T) sequence, can directly obtain the power spectrum of noise intensity.

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