CN102970646B - Loudspeaker abnormal sound detection circuit device and detection method based on constant current source power amplification - Google Patents
Loudspeaker abnormal sound detection circuit device and detection method based on constant current source power amplification Download PDFInfo
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- CN102970646B CN102970646B CN201210437729.6A CN201210437729A CN102970646B CN 102970646 B CN102970646 B CN 102970646B CN 201210437729 A CN201210437729 A CN 201210437729A CN 102970646 B CN102970646 B CN 102970646B
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Abstract
The invention discloses a loudspeaker abnormal sound detection circuit device based on constant current source power amplification. The loudspeaker abnormal sound detection circuit device comprises a high-precision amplitude-adjustable sinusoidal signal generator module, a constant current source power amplification module, an abnormal sound extraction detection module and a base frequency signal analysis feedback module. The invention further relates to a detection method of the detection circuit device. The detection method comprises a first step of providing high-precision and amplitude-adjustable excitation signals through the high-precision amplitude-adjustable sinusoidal signal generator module, a second step of extracting response signals of a loudspeaker from high-precision continuous swept-frequency signals, converting the swept-frequency signals into digital signals, analyzing a base frequency signal frequency spectrum, and feeding a base frequency signal amplitude value back to a signal source to perform amplitude value compensation, and a third step of judging whether abnormal sounds occur in the loudspeaker. According to the loudspeaker abnormal sound detection circuit device and detection method based on constant current source power amplification, a system structure is simple, the environmental noise is not introduced, and whether the abnormal sounds occur in the loudspeaker can be accurately detected.
Description
Technical field
The invention belongs to electroacoustic detection technique field, relate to the abnormal sound detecting circuit device of a kind of loud speaker based on constant-current source power amplifier, the invention still further relates to the detection method of above-mentioned testing circuit device.
Background technology
Because loud speaker research and development are unreasonable and some unforeseen situations in batch production process, cause loud speaker can there is abnormal sound when encouraging normal audio signal, these abnormal sounds can have influence on the auditory perception of people.
Loud speaker be there is to the testing of abnormal sound, traditional method utilizes people's ear to go to distinguish abnormal sound, and this way also exists a large amount of subjective factors, can affect production efficiency and the product quality of loud speaker, therefore, the detection for loud speaker abnormal sound has profound significance.
At present, the detection great majority for loud speaker abnormal sound adopt fixed voltage mode to drive loud speaker, and this detection method is overcoming in nonlinear distortion and transient distortion and cannot take into account.The load loud speaker driven due to power amplifier, neither pure inductance load neither resistive load, the electric current I on loudspeaker voice coil
0with power amplifier output end voltage V
0there is certain phase difference, make negative feedback voltage V
fwith voice coil loudspeaker voice coil electric current I
0not linear relationship, cause transient intermodulation.And constant pressure source power amplifier measures loud speaker abnormal sound, after need to place Sound Attenuator and microphone, by analyzing the sound pressure signal of microphone, judge the performance of loud speaker, this detection system complex structure, can introduce ambient noise, cause interference to result.
Summary of the invention
The object of the present invention is to provide the abnormal sound detecting circuit of a kind of loud speaker based on constant-current source power amplifier and detection method, constant-current source power amplifier is adopted to replace constant pressure source power amplifier, utilize the constant-current characteristics of constant-current source and the infinitely-great characteristic of internal resistance, by measuring the signal of telecommunication at loud speaker two ends, reach the object of the abnormal sound detection of loud speaker; Meanwhile, by the amplitude feedback of fundamental frequency signal to signal generating module, carry out Amplitude Compensation, make loud speaker both end voltage constant, meet the condition that constant pressure source measures loud speaker abnormal sound.
The technical solution adopted in the present invention is, the abnormal sound detecting circuit device of loud speaker based on constant-current source power amplifier, is included the high accuracy amplitude that connected by wire adjustable sinusoidal signal generator module, constant-current source power amplifier module, abnormal sound extracts detection module and fundamental frequency signal analyzes feedback module.
Feature of the present invention is also,
Sinusoidal signal generator module includes signal source generator, programmable attenuator, control tape bandpass filter, and signal source generator is connected with programmable attenuator, control tape bandpass filter respectively by wire.
Constant-current source power amplifier module includes constant-current power amplifier and differential amplifier circuit, and constant-current power amplifier is connected with differential amplifier circuit by wire, constant-current power amplifier is also provided with the wire connecting loud speaker.
Abnormal sound is extracted detection module and includes the program control band stop filter and single-ended amplifier that are connected successively by wire, single-ended amplifier respectively by wire with analysis of spectrum module and be with the playback module of loudspeaker arrangement to be connected.
Fundamental frequency signal is analyzed feedback module and is included and to be linked together DSP module and A/D converter by wire.
Control tape bandpass filter in sinusoidal signal generator module is connected with the constant-current power amplifier in constant-current source power amplifier module by wire, the A/D converter that differential amplifier circuit in constant-current source power amplifier module extracts program control band stop filter in detection module respectively with abnormal sound by wire, fundamental frequency signal is analyzed in feedback module is connected, and abnormal sound extracts program control band stop filter in detection module by wire analyzes the DSP module in feedback module with fundamental frequency signal successively, the programmable attenuator in sinusoidal signal generator module is connected.
Another technical scheme of the present invention is, the detection method of the abnormal sound detecting circuit device of the loud speaker based on constant-current source power amplifier, specifically implements according to following steps:
Step 1, provide high accuracy by the sinusoidal signal generator module that high accuracy amplitude is adjustable and the adjustable pumping signal of amplitude;
There is continuous swept-frequency signal in the signal source generator in sinusoidal signal generator module that high accuracy amplitude is adjustable, utilizes programmable attenuator to decay to continuous swept-frequency signal, and the frequency range of continuous swept-frequency signal controlled;
Step 2, drive loud speaker to produce electroresponse signal with current constant mode, and electroresponse signal is converted to digital signal, analyzing fundamental frequency signal spectrum, fundamental frequency signal amplitude is fed back to signal source generator and carries out amplitude compensation;
Step 3, judge whether loud speaker exists abnormal sound.
The feature of another technical scheme of the present invention is also,
Step 1 is specifically implemented according to following steps:
1) loud speaker to be measured is connected between constant-current source power amplifier and differential amplifier circuit by wire, connect circuit, start the abnormal sound detecting circuit of loud speaker based on constant-current source power amplifier, continuous swept-frequency signal is there is by signal source generator, the spectral magnitude of continuous swept-frequency signal is decayed by programmable attenuator, obtains the continuous swept-frequency signal that can not produce distortion;
2) through 1) process after, continuous swept-frequency signal is adjusted by control tape bandpass filter, the parameter that control tape bandpass filter presets according to user: centre frequency and cut-off frequecy of passband carry out filtering to continuous swept-frequency signal, composition beyond filtering fundamental frequency signal frequency, improve the precision of continuous swept-frequency signal, obtain fundamental frequency signal.
Step 2 is specifically implemented according to following steps:
1) the fundamental frequency signal input constant-current source power amplifier module will obtained in step 1, constant-current power amplifier in constant-current source power amplifier module carries out power amplification to the fundamental frequency signal that step 1 obtains and also loads the loud speaker two ends to be measured connected in step 1, fundamental frequency signal through constant-current power amplifier process drives loud speaker sounding, makes loud speaker two ends to be measured produce electroresponse signal simultaneously;
2) by 1) in the electroresponse signal at loud speaker two ends send into differential amplifier circuit, differential amplifier circuit amplifies difference mode signal, suppresses common mode noise signal, obtains not containing the loud speaker electroresponse signal of outside noise.
Step 3 is specifically implemented according to following steps:
1) analog-to-digital conversion is not carried out containing the loud speaker electroresponse signal of outside noise through A/D converter by obtaining in step 2, change the loud speaker electroresponse signal not containing outside noise into discrete digital signal, by DSP module, discrete digital signal is processed again, part signal identical with fundamental frequency signal in step 1 in discrete digital signal is carried out spectrum analysis, the amplitude of fundamental frequency signal frequency spectrum is fed back to signal source generator by DSP module simultaneously, and signal source generator carries out amplitude compensation to fundamental frequency signal;
DSP module control signal source generator, programmable attenuator, control tape bandpass filter, program control band stop filter modules Frequency Synchronization run, what obtain through step 2 is not admitted to program control band stop filter containing the loud speaker electroresponse signal of outside noise, according to the frequency range of fundamental frequency signal, set the cut-off frequency of program control band stop filter, signal incoherent with fundamental frequency signal in the loud speaker two ends electroresponse signal that filtering is to be detected, obtains voice signal to be detected;
2) by through 1) voice signal to be detected that obtains is delivered to single-ended amplifier, by single-ended amplifier, voice signal to be detected amplified;
3) voice signal to be detected after amplifying is transported to the playback module of analysis of spectrum module and band loudspeaker arrangement, analysis of spectrum module extracts the voice signal to be detected after amplifying, adopt Fourier transform, convert the voice signal to be detected after amplifying to frequency spectrum, if the frequency spectrum of gained is disorderly and unsystematic, and energy exceedes the threshold value preset, illustrate that voice signal to be detected is abnormal sound signal;
The threshold value wherein preset measures by experiment, there is no determined value, the method that specifically obtains is: get 100 normal loud speakers, by measuring, adding up and determining the upper threshold of good loud speaker, then getting 100 malfunctioning speaker, by measuring, the lower limit of definite threshold, what obtain determines a threshold range according to upper threshold and bottom threshold, determines a threshold value according to the requirement of detected loud speaker in threshold range;
Voice signal to be detected after simultaneously amplifying plays back by being with the playback module of loudspeaker arrangement, if hear the sound of non-actuated signal, then illustrates that loud speaker to be detected exists abnormal sound;
Namely when amplify after voice signal frequency spectrum disorderly and unsystematic and band loudspeaker arrangement playback module can play out sound judge loud speaker there is abnormal sound; Otherwise there is not abnormal sound.
Beneficial effect of the present invention is,
1) due to constant current, the infinitely-great characteristic of internal resistance of constant-current source power amplifier, the weak voltage at loud speaker two ends is fluctuated and is easy to detect, be unlikely to be flooded by circuit, improve the reliability of different sound testing result.
2) voltage signal at the inventive method direct-detection loud speaker two ends, does not need in test circuit to arrange the device such as Sound Attenuator, microphone, and make circuit structure simple, can not introduce ambient noise and avoid unnecessary interference, measurement result is accurate.
3) testing circuit is to the abnormal sound extracted through spectrum analysis and loud speaker playback two kinds of processing methods, and comprehensive descision loud speaker, whether containing abnormal sound, ensure that the accuracy of measurement result.
4) method of testing is based on constant-current source power amplifier, the transient intermodulation avoiding constant voltage power amplifier to bring, and makes measurement result more accurate.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of the abnormal sound detection device of loud speaker that the present invention is based on constant-current source power amplifier;
In figure, 1. signal source generator, 2. programmable attenuator, 3. control tape bandpass filter, 4. constant-current source power amplifier, 5. differential amplifier circuit, 6. program control band stop filter, 7. single-ended amplifier, 8. analysis of spectrum module, is 9. with the playback module of loudspeaker arrangement, 10.DSP module, 11.A/D transducer.
Embodiment
Below in conjunction with accompanying drawing and specific implementation method, the present invention is described in detail.
The present invention is based on the abnormal sound detecting circuit device of loud speaker of constant-current source power amplifier, its structure as shown in Figure 1, is included the adjustable sinusoidal signal generator module of the high accuracy amplitude that connected by wire, constant-current source power amplifier module, abnormal sound extracts detection module and fundamental frequency signal analyzes feedback module.
Adjustable sinusoidal signal generator module includes signal source generator 1, programmable attenuator 2, control tape bandpass filter 3, and signal source generator 1 is connected with programmable attenuator 2, control tape bandpass filter 3 respectively by wire.
Constant-current source power amplifier module includes constant-current power amplifier 4 and differential amplifier circuit 5, and constant-current power amplifier 4 is connected with differential amplifier circuit 5 by wire, constant-current power amplifier 4 is also provided with the wire connecting loud speaker.
Abnormal sound is extracted detection module and includes the program control band stop filter 6 and single-ended amplifier 7 that are connected successively by wire, single-ended amplifier 7 respectively by wire with analysis of spectrum module 8 and be with the playback module 9 of loudspeaker arrangement to be connected.
Fundamental frequency signal is analyzed feedback module and is included and to be linked together DSP module 10 and A/D converter 11 by wire.
Control tape bandpass filter 3 in sinusoidal signal generator module is connected with the constant-current power amplifier 4 in constant-current source power amplifier module by wire, the A/D converter 11 that differential amplifier circuit 5 in constant-current source power amplifier module extracts program control band stop filter 6 in detection module respectively with abnormal sound by wire, fundamental frequency signal is analyzed in feedback module is connected, abnormal sound extract in detection module program control band stop filter 6 analyzes the DSP module 10 in feedback module with fundamental frequency signal successively by wire, the programmable attenuator 2 in sinusoidal signal generator module is connected.
The chip of signal source generator 1 adopts integrated chip or utilizes special Direct Digital Synthesis-DDS chip; Programmable attenuator 2 is program control type, according to the amplitude of the continuous swept-frequency signal of difference, by the parameter of user's free setting attenuator, decays, reach the object preventing continuous swept-frequency signal distortion to continuous swept-frequency signal amplitude; Control tape bandpass filter 3 is program control type, can, according to the frequency range of continuous swept-frequency signal, by the parameter of user's free setting filter, only allow fundamental frequency signal pass through, reach the object improving continuous swept-frequency signal precision.
The present invention is based on the abnormal sound detection method of loud speaker of constant-current source power amplifier, its testing circuit as shown in Figure 1, is specifically implemented in such a way:
Step 1, provide high accuracy by high accuracy amplitude adjustable sinusoidal signal generator module and the adjustable pumping signal of amplitude;
There is continuous swept-frequency signal in the signal source generator 1 in sinusoidal signal generator module that high accuracy amplitude is adjustable, utilizes programmable attenuator 2 to decay to continuous swept-frequency signal, and the frequency range of continuous swept-frequency signal controlled by program control band stop filter 3;
1) loud speaker to be measured is connected between constant-current source power amplifier 4 and differential amplifier circuit 5 by wire, connect circuit, start the abnormal sound detecting circuit of loud speaker based on constant-current source power amplifier, continuous swept-frequency signal is there is by signal source generator 1, the spectral magnitude of continuous swept-frequency signal is decayed by programmable attenuator 2, acquisition can not produce the continuous swept-frequency signal of distortion, to prevent continuous swept-frequency signal level too high, produces nonlinear distortion;
2) through 1) process after, continuous swept-frequency signal is adjusted by control tape bandpass filter 3, the parameter that control tape bandpass filter 3 presets according to user: centre frequency and cut-off frequecy of passband carry out filtering to continuous swept-frequency signal, composition beyond filtering fundamental frequency signal frequency, improve the precision of continuous swept-frequency signal, obtain fundamental frequency signal.
Step 2, drive loud speaker to produce electroresponse signal with current constant mode, and electroresponse signal is converted to digital signal, analyzing fundamental frequency signal spectrum, fundamental frequency signal amplitude is fed back to signal source reflector and carries out amplitude compensation;
1) the fundamental frequency signal input constant-current source power amplifier module will obtained in step 1, the fundamental frequency signal that constant-current power amplifier in constant-current source power amplifier module 4 pairs of steps 1 obtain carries out power amplification and also loads the loud speaker two ends to be measured connected in step 1, the fundamental frequency signal processed through constant-current power amplifier 4 drives loud speaker sounding, makes loud speaker two ends to be measured produce electroresponse signal simultaneously;
Constant-current power amplifier 4 utilizes constant-current source current constant and the infinitely-great characteristic of internal resistance, and circuit can capture the electroresponse signal at loud speaker two ends observantly, makes measurement result have very high accuracy;
2) by 1) in loud speaker two ends electroresponse signal send into differential amplifier circuit 5, differential amplifier circuit 5 amplifies difference mode signal, suppress common mode noise signal, obtain not containing the loud speaker electroresponse signal of outside noise, the noise that can reduce like this to be caused by external environment is to the interference of loud speaker two ends electroresponse signal.
Step 3, judge whether loud speaker exists abnormal sound;
1) analog-to-digital conversion is not carried out containing the loud speaker electroresponse signal of outside noise through A/D converter 11 by obtaining in step 2, change the loud speaker electroresponse signal not containing outside noise into discrete digital signal, by DSP module 10, discrete digital signal is processed again, part signal identical with fundamental frequency signal in step 1 in discrete digital signal is carried out spectrum analysis, the amplitude of fundamental frequency signal frequency spectrum is fed back to signal source generator 1 by DSP module 10 simultaneously, and signal source generator 1 pair of fundamental frequency signal carries out amplitude compensation;
DSP module 10 control signal source generator 1, programmable attenuator 2, control tape bandpass filter 3, program control band stop filter 6 modules Frequency Synchronization are run, what obtain through step 2 is not admitted to program control band stop filter 6 containing the loud speaker electroresponse signal of outside noise, according to the frequency range of fundamental frequency signal, set the cut-off frequency of program control band stop filter 6, signal incoherent with fundamental frequency signal in the loud speaker two ends electroresponse signal that filtering is to be detected, obtains voice signal to be detected;
2) by through 1) voice signal to be detected that obtains is delivered to single-ended amplifier 7, by single-ended amplifier 7, voice signal to be detected amplified;
3) voice signal to be detected after amplifying is transported to the playback module 9 of analysis of spectrum module 8 and band loudspeaker arrangement, analysis of spectrum module 8 extracts the voice signal to be detected after amplifying, adopt Fourier transform, convert the voice signal to be detected after amplifying to frequency spectrum, if the frequency spectrum of gained is disorderly and unsystematic, and energy exceedes the threshold value preset, illustrate that voice signal to be detected is abnormal sound signal;
The threshold value wherein preset measures by experiment, there is no determined value, the method that specifically obtains is: get 100 normal loud speakers, by measuring, adding up and determining the upper threshold of good loud speaker, then getting 100 malfunctioning speaker, by measuring, the lower limit of definite threshold, what obtain determines a threshold range according to upper threshold and bottom threshold, determines a threshold value according to the requirement of detected loud speaker in threshold range; Producer can come according to the technological requirement of producing loud speaker to select a numerical value, generally high-grade product in this threshold interval, and threshold value is lower; And low-grade product, threshold value is higher.
Voice signal to be detected after simultaneously amplifying is played back by the playback module 9 of band loudspeaker arrangement, if hear the sound of non-actuated signal, then illustrates that loud speaker to be detected exists abnormal sound;
When amplify after voice signal frequency spectrum disorderly and unsystematic and band loudspeaker arrangement playback module 9 can play out sound judge loud speaker there is abnormal sound; Otherwise there is not abnormal sound.
The abnormal sound detection device of loud speaker that the present invention is based on constant-current source power amplifier is divided into four module: sinusoidal signal generator module that high accuracy amplitude is adjustable, constant-current source power amplifier module, abnormal sound extract detection module, fundamental frequency signal analyzes feedback module; High accuracy amplitude is adjustable, and sinusoidal signal generator provides high accuracy and the continuous swept-frequency signal that amplitude is adjustable, be loaded on loud speaker to be measured by constant-current source power amplifier module, abnormal sound extracts detection module and detects loud speaker both end voltage signal, extract abnormal sound part, fundamental frequency signal analyzes feedback module by fundamental frequency signal amplitude feedback to signal source generator 1, make loud speaker both end voltage to be measured constant, meet constant voltage power amplifier simultaneously and measure abnormal sound condition.
Sinusoidal signal generator module that high accuracy amplitude is adjustable, continuous swept-frequency signal is sent by signal source generator 1, programmable attenuator 2 carries out amplitude fading to continuous swept-frequency signal, control tape bandpass filter 3 carries out frequency range control, frequency content beyond filtering fundamental frequency signal, improves the precision of continuous swept-frequency signal; The chip of signal source generator 1 adopts integrated chip or utilizes special Direct Digital Synthesis-DDS chip; Programmable attenuator 2, is designed to program control type, according to the amplitude of the continuous swept-frequency signal of difference, by the parameter of user's free setting attenuator, decays, reach the object preventing continuous swept-frequency signal distortion to continuous swept-frequency signal amplitude; Control tape bandpass filter 3, is designed to program control type, can, according to the frequency range of continuous swept-frequency signal, by the parameter of user's free setting filter, only allow fundamental frequency signal pass through, reach the object improving continuous swept-frequency signal precision.
Constant-current source power amplifier module, is carried on loud speaker to be measured with constant-current source power amplifier 4 by continuous swept-frequency signal power amplification, detects the voltage signal at loud speaker two ends, voltage signal carried out differential amplification process by differential amplifier circuit 5; Constant-current source power amplifier 4 wherein utilizes constant-current source current constant, the infinitely-great characteristic of internal resistance, can measure the voltage signal at loud speaker two ends observantly, makes measurement result have very high accuracy; Differential amplifier circuit 5 plays amplification difference mode signal, suppresses common-mode noise, and the noise that reduction environment causes is to the effect of loudspeaker response signal disturbing.
Abnormal sound extracts detection module, by fundamental component in the program control band stop filter 6 filtering loudspeaker response signal of telecommunication, extract abnormal sound, after gained abnormal sound is amplified by single-ended amplifier 7, simultaneously through the process of the playback module 9 of analysis of spectrum module 8, band loudspeaker arrangement, by two-way result comprehensive descision loud speaker to be measured whether containing abnormal sound; Program control band stop filter 6 is program control type, according to the frequency range of continuous swept-frequency signal, by the parameter of user's free setting filter, can reach the object of the frequency content that continuous swept-frequency signal is corresponding in just filtering loud speaker electroresponse, extract abnormal sound; Analysis of spectrum module 8 adopts Fourier transform, converts the voice signal of extraction to frequency spectrum, by observation frequency spectrum, determines whether abnormal sound; The voice signal of extraction, with a normal loudspeaker arrangement, is play by normal loud speaker, is determined whether abnormal sound by the playback module 9 with loudspeaker arrangement.
Fundamental frequency signal analyzes feedback module, A/D converter 11 is sent in the output of differential amplifier circuit 5 and is converted to digital signal by analog signal, gained digital signal is sent in DSP module 10, analysis of spectrum process is carried out to fundamental frequency signal, and by the amplitude feedback of fundamental frequency signal to signal source generator 1, carry out amplitude compensation, make the voltage constant at loud speaker two ends, meet the terms and conditions that constant voltage power amplifier detects abnormal sound; DSP module 10 also has the effect of control signal source generator 1, programmable attenuator 2, control tape bandpass filter 3, program control band stop filter 6 modules Frequency Synchronization simultaneously.
Traditional constant pressure source mensuration due to the nonlinear impedance of loud speaker, can cause transient intermodulation, affects measurement result.Constant pressure source method of measurement need detect the performance of loud speaker by microphone, the introducing of microphone can bring interference to circuit, is not in this way suitable for the detection of loud speaker abnormal sound.
The present invention is based on constant flow method, with linear resistive element flowing through the current feedback of loudspeaker voice coil to the input of constant-current source power amplifier, constant-current source power amplifier is made to drive the loud speaker of load in fixed current mode, making feedback loop signals linear with flowing through loudspeaker voice coil electric current, doing so avoids the transient intermodulation that constant-voltage method brings due to nonlinear loudspeaker impedance.Due to constant-current characteristics and the infinitely-great characteristic of internal resistance of constant-current source, even if make the faint voltage fluctuation in loud speaker two ends also be easy to catch, be unlikely to be flooded by circuit, improve the reliability of measurement.In view of the above characteristic of constant-current source power amplifier, judge speaker performance by the voltage signal detecting loud speaker two ends, save the device such as Sound Attenuator, microphone, avoid too much interference.
Present invention employs succinctly, accurately method judge loud speaker whether containing abnormal sound, by measuring the signal of telecommunication at loud speaker two ends, after the gained signal of telecommunication being carried out difference, amplification, filtering process, do analysis of spectrum and loud speaker audition respectively, whether comprehensive descision loud speaker is containing abnormal sound.
Claims (2)
1. based on the abnormal sound detecting circuit device of loud speaker of constant-current source power amplifier, it is characterized in that, include the adjustable sinusoidal signal generator module of the high accuracy amplitude that connected by wire, constant-current source power amplifier module, abnormal sound extracts detection module and fundamental frequency signal analyzes feedback module;
Described sinusoidal signal generator module includes signal source generator (1), programmable attenuator (2), control tape bandpass filter (3), described signal source generator (1) is connected with described programmable attenuator (2), described control tape bandpass filter (3) respectively by wire, and described programmable attenuator (2) is connected with described control tape bandpass filter (3) by wire; The chip of described signal source generator (1) adopts integrated chip or special Direct Digital Synthesis-DDS chip;
Described adjustable sinusoidal signal generator module, continuous swept-frequency signal is sent by signal source generator (1), described programmable attenuator (2) carries out amplitude fading to continuous swept-frequency signal, control tape bandpass filter (3) carries out frequency range control, frequency content beyond filtering fundamental frequency signal, improves the precision of continuous swept-frequency signal;
Described constant-current source power amplifier module includes power amplifier (4) and differential amplifier circuit (5), described constant-current source power amplifier (4) is connected with described differential amplifier circuit (5) by wire, and described constant-current source power amplifier (4) is also provided with the wire connecting loud speaker to be measured;
Described constant-current source power amplifier module, with constant-current source power amplifier (4), continuous swept-frequency signal power amplification is carried on loud speaker to be measured, detect the voltage signal at loud speaker two ends, voltage signal is carried out differential amplification process by differential amplifier circuit (5);
Described abnormal sound is extracted detection module and includes the program control band stop filter (6) and single-ended amplifier (7) that are connected successively by wire, described single-ended amplifier (7) respectively by wire with analysis of spectrum module (8) and be with the playback module of loudspeaker arrangement (9) to be connected;
Described abnormal sound extracts detection module, abnormal sound is extracted with program control band stop filter (6), after gained abnormal sound is amplified by single-ended amplifier (7), simultaneously through the process of the playback module (9) of analysis of spectrum module (8), band loudspeaker arrangement, by two-way result comprehensive descision loud speaker to be measured whether containing abnormal sound;
Described fundamental frequency signal is analyzed feedback module and is included and to be linked together DSP module (10) and A/D converter (11) by wire;
Control tape bandpass filter (3) in described sinusoidal signal generator module is connected with the constant-current source power amplifier (4) in described constant-current source power amplifier module by wire, differential amplifier circuit (5) in described constant-current source power amplifier module extracts the program control band stop filter (6) in detection module respectively with described abnormal sound by wire, the A/D converter (11) that fundamental frequency signal is analyzed in feedback module connects, the DSP module (10) in feedback module analyzed successively by the described abnormal sound program control band stop filter (6) extracted in detection module with described fundamental frequency signal by wire, programmable attenuator (2) in described sinusoidal signal generator module connects, described DSP module (10) is connected with signal source generator (1), control tape bandpass filter (3) respectively by wire.
2., as claimed in claim 1 based on a detection method for the abnormal sound detecting circuit device of loud speaker of constant-current source power amplifier, it is characterized in that, specifically implement according to following steps:
Step 1, provide high accuracy by the sinusoidal signal generator module that high accuracy amplitude is adjustable and the adjustable pumping signal of amplitude;
There is continuous swept-frequency signal in the signal source generator (1) in sinusoidal signal generator module that high accuracy amplitude is adjustable, utilizes programmable attenuator to decay to continuous swept-frequency signal, and the frequency range of continuous swept-frequency signal controlled;
Described step 1 is specifically implemented according to following steps:
Step 1.1, loud speaker to be measured is connected between constant-current source power amplifier (4) and differential amplifier circuit (5) by wire, connect circuit, start the abnormal sound detecting circuit of loud speaker based on constant-current source power amplifier, continuous swept-frequency signal is there is by signal source generator (1), the spectral magnitude of continuous swept-frequency signal is decayed by programmable attenuator (2), obtains the continuous swept-frequency signal that can not produce distortion;
Step 1.2, through step 1.1 process after, continuous swept-frequency signal is adjusted by control tape bandpass filter (3), the parameter that control tape bandpass filter (3) presets according to user: centre frequency and cut-off frequecy of passband carry out filtering to continuous swept-frequency signal, composition beyond filtering fundamental frequency signal frequency, improve the precision of continuous swept-frequency signal, obtain fundamental frequency signal;
Step 2, drive loud speaker to produce electroresponse signal with current constant mode, and electroresponse signal be converted to digital signal, analyzing fundamental frequency signal spectrum, fundamental frequency signal amplitude is fed back to signal source generator and carries out amplitude compensation, specifically implement according to following steps:
Step 2.1, the fundamental frequency signal input constant-current source power amplifier module will obtained in step 1, constant-current power amplifier (4) in constant-current source power amplifier module carries out power amplification to the fundamental frequency signal that step 1 obtains and also loads the loud speaker two ends to be measured connected in step 1, the fundamental frequency signal processed through constant-current power amplifier (4) drives loud speaker sounding, makes loud speaker two ends to be measured produce electroresponse signal simultaneously;
Step 2.2, by the electroresponse signal at loud speaker two ends in step 2.1 send into differential amplifier circuit (5), differential amplifier circuit (5) amplifies difference mode signal, suppress common mode noise signal, obtain not containing the loud speaker electroresponse signal of outside noise;
Step 3, judge whether loud speaker exists abnormal sound, specifically implement according to following steps:
Step 3.1, analog-to-digital conversion is not carried out containing the loud speaker electroresponse signal of outside noise through A/D converter (11) by obtaining in step 2, change the loud speaker electroresponse signal not containing outside noise into discrete digital signal, by DSP module (10), discrete digital signal is processed again, part signal identical with fundamental frequency signal in step 1 in discrete digital signal is carried out spectrum analysis, the amplitude of fundamental frequency signal frequency spectrum is fed back to signal source generator (1) by DSP module (10) simultaneously, signal source generator (1) carries out amplitude compensation to fundamental frequency signal,
DSP module (10) control signal source generator (1), programmable attenuator (2), control tape bandpass filter (3), program control band stop filter (6) modules Frequency Synchronization are run, what obtain through step 2 is not admitted to program control band stop filter (6) containing the loud speaker electroresponse signal of outside noise, according to the frequency range of fundamental frequency signal, set the cut-off frequency of program control band stop filter (6), signal incoherent with fundamental frequency signal in the loud speaker two ends electroresponse signal that filtering is to be detected, obtains voice signal to be detected;
Step 3.2, the voice signal to be detected obtained through step 3.1 is delivered to single-ended amplifier (7), by single-ended amplifier (7), voice signal to be detected is amplified;
Voice signal to be detected after step 3.3, amplification is transported to the playback module (9) of analysis of spectrum module (8) and band loudspeaker arrangement, analysis of spectrum module (8) extracts the voice signal to be detected after amplifying, adopt Fourier transform, convert the voice signal to be detected after amplifying to frequency spectrum, if the frequency spectrum of gained is disorderly and unsystematic, and energy exceedes the threshold value preset, illustrate that voice signal to be detected is abnormal sound signal;
The threshold value wherein preset measures by experiment, there is no determined value, the method that specifically obtains is: get 100 normal loud speakers, by measuring, adding up and determining the upper threshold of good loud speaker, then getting 100 malfunctioning speaker, by measuring, the lower limit of definite threshold, what obtain determines a threshold range according to upper threshold and bottom threshold, determines a threshold value according to the requirement of detected loud speaker in threshold range;
Voice signal to be detected after simultaneously amplifying is played back by the playback module (9) of band loudspeaker arrangement, if hear the sound of non-actuated signal, then illustrates that loud speaker to be detected exists abnormal sound;
Namely when amplify after voice signal frequency spectrum disorderly and unsystematic and band loudspeaker arrangement playback module (9) can play out sound judge loud speaker there is abnormal sound; Otherwise there is not abnormal sound.
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