CN105305993B - A kind of compression limiter - Google Patents
A kind of compression limiter Download PDFInfo
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- CN105305993B CN105305993B CN201510862335.9A CN201510862335A CN105305993B CN 105305993 B CN105305993 B CN 105305993B CN 201510862335 A CN201510862335 A CN 201510862335A CN 105305993 B CN105305993 B CN 105305993B
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Abstract
The present invention provides a kind of compression limiters, comprising: gain regulation module, for exporting the first output signal, and according to the first output signal feedback regulation for realizing the first signal gain of input signal compression clipping；Public address module exports the second output signal for carrying out power amplification to the first output signal；Clipping control module, for according to the clipping distortion occurred in the second output signal, the second signal gain of clipping to be compressed in feedback regulation for realizing input signal；Slicing amplitude generator, for according to slicing amplitude adjust automatically clipping amplitude；It compresses limiter and compression clipping is carried out to input signal according to the first signal gain and second signal gain, the second output signal for compressing limiter output is controlled and is exported in clipping amplitude.The clipping distortion occurred in its second output signal of automatic elimination, improves the output sound quality of public address module, promotes user experience, while by slicing amplitude and the control of clipping amplitude in relatively-stationary ratio.
Description
Technical field
The present invention relates to audio signal processing technique field more particularly to a kind of compression limiters.
Background technique
The sense of hearing dynamic range of the mankind is up to 120dB (decibel), and the maximum acoustic that can be heard is bigger than minimum sound by 1,000,000
Times.When public address equipment is in playing audio signal, it is often limited to the maximum that the bottom of public address equipment itself is made an uproar with public address equipment
Fan-out capability (dynamic range of equipment), e.g., the bottom that lesser sound can be submerged in system make an uproar in can not hear, and maximum sound
Sound will receive the limitation of public address equipment maximum output ability, or even will appear clipping distortion.In order to solve this problem, it introduces
The dynamic of voice signal is handled, by reducing the dynamic range of sound, make to amplify set can normal play, compress limiting technology
Just belong to one such technology.
The basic principle of compression limiting technology is usually: first improving the entire gain of source of sound, flood lesser sound will not
Not in the bottom of system is made an uproar, it can be heard；When voice signal reaches the threshold threshold value of setting, according to the compression ratio of setting,
The gain of reduction system, to reduce the dynamic range of sound；When voice signal has reached the maximum output ability of system, output
No longer increase with the increase of input, prevents the clipping distortion of voice signal, the input signal of system and output letter during being somebody's turn to do
Number relational graph as shown in Figure 1, diagram in V1 be above-mentioned setting threshold threshold value, V2 be above-mentioned system reach maximum output energy
The voltage value of power, VLFor the clipping amplitude of system, and the region that the amplitude of input signal is 0~V1 is linear zone, input signal
Amplitude be V1~V2 region be compressional zone, the amplitude of input signal is more than that the region of V2 is clipping area.In addition, when system
When dynamic range is smaller, the algorithm with clipping function will use to realize above-mentioned purpose, as shown in Fig. 2, VLFor the limit of system
Width amplitude, when the amplitude of input signal reaches V, output no longer increases with the increase of input, corresponding with Fig. 1, input letter
Number amplitude be 0~V region be linear zone, the amplitude of input signal is more than that the region of V is clipping area.
During compressing clipping, two parameters are critically important, respectively starting time and release time.Wherein, start
Time is to control the time in threshold threshold value beyond threshold threshold value to signal from system detection to signal；Release time is when letter
After number becoming smaller, the time that the change in gain of clipping is eliminated is compressed, as shown in Figure 3.It can be seen from the figure that when input signal reaches
The maximum output ability of system, then system reduces the gain of system according to preset starting time A, until by output signal control
System is in threshold threshold value；When input signal becomes smaller, system increases the gain of system according to preset release time B in right amount, increases
Output signal is simultaneously controlled in threshold threshold value.
But during existing compression limiter starts the time, due to various reasons, easily there is slicing in output signal
The phenomenon that truncation.Such as, the starting time is longer, it may appear that the phenomenon that slicing truncation；For another example, when occur output loading become weight, power supply
When the application conditions such as voltage is lower, temperature is got higher change, the dynamic range of public address equipment can reduce, and also will appear slicing at this time and cut
The phenomenon that top, waits.System can generate a large amount of harmonic distortion signal when there is the phenomenon that slicing truncation therewith, to cause
Equipment sense of hearing is deteriorated, and is easily damaged loudspeaker.
Summary of the invention
In view of the above-mentioned problems, the present invention is intended to provide a kind of compression limiter, is eliminated existing by a clipping control module
There is the clipping distortion occurred in compression limiter.
Technical solution provided by the invention is as follows:
A kind of compression limiter, comprising: gain regulation module, public address module and clipping control module, wherein
The gain regulation module exports the first output signal according to the input signal of the compression limiter；And according to
The first signal gain of clipping is compressed in first output signal, feedback regulation for realizing the input signal；
The public address module is connect with the gain regulation module, and the public address module is defeated to the gain regulation module
The first output signal out carries out power amplification, exports the second output signal；
The clipping control module, connect with the gain regulation module and the public address module respectively, the slicing control
The clipping distortion occurred in the second output signal that molding root tuber is exported according to the public address module, feedback regulation is for realizing described
The second signal gain of input signal compression clipping；
The compression limiter according to first signal gain and the second signal gain to the input signal into
Second output signal of the compression limiter output is controlled and is exported in clipping amplitude by row compression clipping.
In the technical scheme, amplified by the input signal that gain regulation module inputs system, compress and
Clipping export the first output signal, then by public address module to the first output signal amplify generation the second output signal into
Row output.In order to eliminate the clipping distortion as caused by public address module, using clipping control module according to there is clipping distortion
Second output signal carries out feedback regulation to the gain of input signal, improves the sense of hearing of public address equipment.
It is further preferred that further include a Gain selector in the compression limiter, the Gain selector respectively with
The gain regulation module is connected with the clipping control module, and the Gain selector is according to first signal gain and institute
Second signal Gain generating system signal gain is stated, the compression limiter realizes the input according to the system signal gain
The compression clipping of signal.
In the technical scheme, selection energy is carried out in the first signal gain and second signal gain using Gain selector
The yield value of the clipping distortion occurred in current system is enough eliminated as system signal gain.
It is further preferred that the Gain selector is in first signal gain and second letter in synchronization
Select lesser yield value as the yield value in system signal gain in number gain, the compression limiter is according to the system
Signal gain realizes the compression clipping of the input signal.
In the technical scheme, Gain selector selects lesser yield value in the first signal gain and the second gain signal
As system gain signal, to controlling the second output signal of output in the dynamic range of public address equipment.
It is further preferred that including distortion detector and the second sequence controller in the clipping control module, wherein
The distortion detector is connect with the public address module, and the distortion detector is for detecting the public address module
Whether there is clipping distortion in second output signal of output；
Second sequence controller, connect with the distortion detector and the Gain selector respectively, cuts when described
Wave detector detects that clipping distortion occurs in second output signal, and second sequence controller is according to second output
Signal adjusts second signal gain, and second signal gain adjusted is inputted the Gain selector.
In the technical scheme, whether there is clipping distortion in the second output signal of distortion detector real-time detection, when
There is clipping distortion, then the then adjust automatically second signal gain of the second sequence controller, rapidly by the width of the second output signal
Value control eliminates the clipping distortion in slicing amplitude；Certainly, if not occurring clipping distortion in the second output signal, the
Two sequence controllers do not work.
It is further preferred that in second sequence controller:
When there is clipping distortion in second output signal, and second sequence controller starts according to preset slicing
Between, reduce the yield value of the second signal gain；And within the slicing starting time, the gain of the second signal gain
Reduction speed is greater than the gain reduction speed of first signal gain；
When the second output signal clipping distortion is eliminated, when second sequence controller is discharged according to preset slicing
Between, increase the yield value of the second signal gain.
In the technical scheme, within the slicing starting time, the yield value reduction speed of second signal gain is greater than first
The yield value reduction speed of signal gain, could rapid elimination clipping distortion on the basis of original.
It is further preferred that including a variable gain amplifier, compression control amplifier, ratio in the gain regulation module
Compared with device and the first sequence controller, wherein
The variable gain amplifier is connect with the Gain selector, the system exported according to the Gain selector
Signal gain amplifies input signal, exports the first output signal；
The compression control amplifier, connect with the variable gain amplifier, is adjusted according to first output signal
First reference voltage；
The comparator is connect with the variable gain amplifier and the compression control amplifier, the comparison respectively
The amplitude of first output signal and first reference voltage are compared by device；
First sequence controller, connect with the Gain selector and the comparator respectively, first timing
Controller adjusts the first signal gain according to the comparison result of the comparator, and the first signal gain adjusted is inputted institute
State Gain selector.
It is further preferred that in the compression control amplifier:
When the amplitude of first output signal is less than the first compression threshold threshold value, the compression control amplifier is by institute
The first reference voltage is stated to draw high；
When the amplitude of first output signal is between the first compression threshold threshold value and the first clipping threshold threshold value, institute
It states compression control amplifier and the first reference voltage is generated according to preset compression ratio；
When the amplitude of first output signal is greater than the first clipping threshold threshold value, the compression control amplifier will be described
First reference voltage constant control corresponding voltage value in the compression limiter output violent change.
And/or
In the comparator:
When the amplitude of first output signal be greater than compression control amplifier output the first reference voltage when, send into
Enter to start time command to first sequence controller；
When the amplitude of first output signal be less than compression control amplifier output the first reference voltage when, send into
Entering release time instructs to first sequence controller.
It is further preferred that in first sequence controller:
When first sequence controller receives the time command into starting, the first sequence controller root
According to the preset starting time, reduce the yield value of first signal gain；
When first sequence controller receives the instruction into release time, the first sequence controller root
According to preset release time, increase the yield value of first signal gain；
The starting time starts the time much larger than the slicing.
In the technical scheme, the starting time is to detect that the first output signal has exceeded the first clipping threshold threshold value to general
It controls the time in the first clipping threshold threshold value；And the slicing starting time is that the second output signal clipping distortion occurs
(amplitude of the second output signal has exceeded slicing amplitude) arrives and is controlled the time in slicing amplitude.And under normal circumstances,
Often than clipping amplitude, (the first clipping threshold threshold value and clipping amplitude Cheng Ding are than relationship and the first clipping threshold threshold for slicing amplitude
It is worth smaller than clipping amplitude) greatly, therefore it is certainly longer than the slicing starting time to start the time.Again it is desirable that elimination clipping loses as early as possible
Very, thus slicing starting the time be often arranged it is shorter, still here starting the time can more than slicing start the time it is long.
It is further preferred that further include in the compression limiter one respectively with the public address module and the compression control
The slicing amplitude generator of amplifier connection,
The slicing amplitude generator obtains the slicing amplitude of the public address module in real time, and the slicing amplitude is sent
To the compression control amplifier；The compression control amplifier is according to the slicing amplitude adjustment received first ginseng
Voltage is examined, and then adjusts the clipping amplitude in the compression limiter.
In practical applications, with the diminution of public address equipment dynamic range, slicing amplitude becomes closer to clipping amplitude, and
When differing too small between slicing amplitude and clipping amplitude, starting time and release time in the first timing control unit and
The setting of slicing starting time and slicing release time in second sequence controller can become unusual difficulty, naturally can be to pressure
Feedback regulation in contracting limiter brings certain interference, it is easy to the noises such as noise or whoop occurs, in order to solve this
One problem, slicing amplitude generator is arranged in compression limiter in we, adjusts clipping amplitude according to slicing amplitude, and will limit
Width amplitude and the control of slicing amplitude are in preset ratio.
It is further preferred that the slicing amplitude generator is cut according to the acquisition of the equivalent load access of scaled down
Wave amplitude；
It is specifically included in the slicing amplitude generator: a PMOS transistor, a NMOS transistor, an equivalent resistance,
One divider resistance, the second divider resistance, third divider resistance, the 4th divider resistance and amplifier, wherein
The grounded-grid of the PMOS transistor, drain electrode connect power supply, source electrode respectively with one end of the equivalent resistance and institute
State one end connection of the first divider resistance；The grid of the NMOS transistor connect power supply, source electrode ground connection, drain electrode respectively with it is described etc.
Imitate one end connection of the other end and the third divider resistance of resistance；The other end of first divider resistance respectively with it is described
The connection of the positive input terminal of one end of second divider resistance and the amplifier；The other end of the third divider resistance respectively with institute
State one end of the 4th divider resistance and the negative input end connection of the amplifier；The other end of second divider resistance with it is described
The output end of amplifier connects；The other end of 4th divider resistance accesses the input common mode voltage in the public address module；
The output end of the amplifier is connect with the compression control amplifier.
Compression limiter provided by the invention, can bring it is following the utility model has the advantages that
In the present invention, gain regulation module feeds back the first signal gain according to the first output signal from output
It adjusting, clipping control module carries out feedback regulation to the second gain signal according to the second output signal for clipping distortion occur,
And select to eliminate the gain of current clipping distortion in the first signal gain and the second gain signal using Gain selector
Value (in the first signal gain and second signal gain selects lesser yield value as system signal as system signal gain
Gain), to being eliminated automatically due to starting overlong time in the second output signal or become weight, supply voltage due to output loading
Be lower, the application conditions variation such as temperature is got higher when caused by public address module reduced dynamic range and the clipping distortion that occurs, improve
The output sound quality of public address module promotes user experience；
Further more, in the present invention, distortion detector and the second sequence controller being arranged in clipping control module, is working
In the process, whether there is slicing mistake first with the second output signal exported in distortion detector real-time detection public address module
Very, once the second sequence controller of clipping distortion occur starts time reduction second signal gain according to preset slicing immediately
Yield value, to eliminate the clipping distortion.After clipping distortion is eliminated, the second sequence controller is released according to preset immediately
Putting the time slowly by signals revivification and controls in clipping amplitude, simple and convenient, and can be rapidly achieved the purpose of the present invention；
In addition, in the present invention, in order to solve the problems, such as that differing too small with clipping amplitude by slicing amplitude causes, Wo Men
It compresses and is provided with slicing amplitude generator in limiter, amplified especially by the equivalent load access of a scaled down
Slicing amplitude in module, and the slicing amplitude of acquisition is sent to compression control amplifier, and then realize to clipping amplitude
Adjustment.By slicing amplitude and the control of clipping amplitude in relatively-stationary ratio, it can smoothly eliminate to compress limiter and cut
Wave distortion, while other noises will not be caused.
Detailed description of the invention
Below by clearly understandable mode, preferred embodiment is described with reference to the drawings, to above-mentioned characteristic, technical characteristic,
Advantage and its implementation are further described.
Fig. 1 is input signal and output signal relational graph in existing compression limiter；
Fig. 2 is input signal and output signal relational graph when existing compression limiter dynamic range is smaller；
Fig. 3 is output signal in existing compression limiter with input signal variation diagram and system gain figure；
Fig. 4 is the structural schematic diagram that the first embodiment of limiter is compressed in the present invention；
Fig. 5 is the structural schematic diagram that second of embodiment of limiter is compressed in the present invention；
Fig. 6 is the structural schematic diagram that the third embodiment of limiter is compressed in the present invention；
Fig. 7 is the relational graph in the present invention between the first signal gain, second signal gain and system signal gain；
Fig. 8 is the structural schematic diagram that the 4th kind of embodiment of limiter is compressed in the present invention；
Fig. 9 is the relational graph in the present invention between the first output signal and the first reference voltage；
Figure 10 is the structural schematic diagram that the 5th kind of embodiment of limiter is compressed in the present invention；
Figure 11 is the second output signal in the present invention with the variation relation figure of slicing amplitude；
Figure 12 is reference voltage in the present invention with the variation relation figure of slicing amplitude；
Figure 13 is slicing amplitude generator circuitry figure in the present invention；
Figure 14 be the present invention in include slicing amplitude generator compression control amplifier output the second output signal
Schematic diagram.
Drawing reference numeral explanation:
A- starts time, B- release time, and C- slicing starts the time, and D- slicing release time, Vref- first is with reference to electricity
Pressure, the-the second reference voltage of Vref ', the amplitude of the first output signal of Vo1-, V1- the first compression threshold threshold value, V1 '-the second compress
Threshold threshold value, V2- the first clipping threshold threshold value, V2 ' the-the second clipping threshold threshold value, R- equivalent resistance, the first divider resistance of R1-,
The second divider resistance of R2-, R3- third divider resistance, the 4th divider resistance of R4-, Q1-NMOS pipe, Q2-PMOS pipe, W- amplifier,
VCM- input common mode voltage；
100- compresses limiter, 110- gain regulation module, 120- public address module, 130- clipping control module, 140- increasing
Beneficial selector, 131- distortion detector, the second sequence controller of 132-, 111- variable gain amplifier, 112- compression control are put
Big device, 113- comparator, the first sequence controller of 114-, 150- slicing amplitude generator.
Specific embodiment
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, Detailed description of the invention will be compareed below
A specific embodiment of the invention.It should be evident that drawings in the following description are only some embodiments of the invention, for
For those of ordinary skill in the art, without creative efforts, it can also be obtained according to these attached drawings other
Attached drawing, and obtain other embodiments.
It is illustrated in figure 4 the first embodiment structure schematic diagram of compression limiter 100 provided by the invention, it can from figure
It include: gain regulation module 110, public address module 120 and clipping control module in the compression limiter 100 to find out
130, wherein public address module 120 is connect with gain regulation module 110, clipping control module 130 respectively with gain regulation module
110 and public address module 120 connect.During the work time, gain regulation module 110 is first using the system signal gain preset
The first output signal of output is amplified to the input signal of system input, and judges the amplitude and first of first output signal
The relationship of compression threshold threshold value V1/ the first clipping threshold threshold value V2.If the amplitude of the first output signal has exceeded the first compression door
Sill threshold value V1/ the first clipping threshold threshold value V2, then gain regulation module 110 can be used according to first output signal, feedback regulation
In the first signal gain (pass of the first signal gain and above system signal gain here for carrying out compression clipping to input signal
System is: if subsequent second output signal does not occur clipping distortion, compressing limiter 100 using first signal gain as system
The compression clipping of signal gain realization input signal).Public address module 120 (i.e. public address equipment) receive the first output signal it
Afterwards, power amplification is carried out to it immediately and exports the second output signal, and drives the loudspeaker output connecting with public address module 120 should
Second output signal.
The above description is that the workflows for compressing limiter 100 under normal circumstances, if due to various reasons (including starting
Time A is too long, causes the dynamic range of public address equipment that can reduce due to various reasons etc.), it is exported in the second output signal
Clipping distortion, at this time clipping control module 130 carries out feedback tune to second signal gain according to the second output signal of output
Section.
Finally, compression limiter 100 carries out compression limit to input signal according to the first signal gain and second signal gain
The amplitude for compressing the second output signal that limiter 100 exports is controlled and is exported in clipping amplitude by width, and elimination clipping loses
Very.Certainly, if not occurring clipping distortion in the second output signal, then clipping control module 130 will not act, i.e., will not
Feedback regulation is carried out to second signal gain, the yield value of second signal gain at this time is always maintained at preset clipping yield value,
At this point, compression limiter 100 is using the first signal gain as system signal gain.
It is noted that in this embodiment, since the effect of the first signal gain and second signal gain is all to use
Regulate and control in input signal；When the amplitude of input signal is excessive (be more than clipping amplitude), in the first signal gain and the
Select yield value appropriate by the control of the second output signal in clipping amplitude in binary signal gain；When output signal amplitude is too small
When (be less than clipping amplitude), similarly select yield value appropriate to input from the first signal gain and second signal gain
Signal is amplified and is exported.When the feedback regulation of the first signal gain not can solve the clipping distortion, clipping control module
130 by carrying out the purpose that elimination clipping distortion is realized in feedback regulation to second signal gain.Thus, since clipping distortion
Occur to clipping distortion during eliminating, clipping control module 130 will necessarily rapidly reduce the gain of second signal gain
Value, and the fall off rate of second signal gain is greater than the fall off rate of the first signal gain, and compresses clipping in this course
Device 100 can be only achieved the mesh of elimination clipping distortion using the yield value in second signal gain adjusted as system gain value
's.
Above embodiment is improved, second of embodiment is obtained, as shown in figure 5, in the first embodiment
On the basis of, it further include a Gain selector 140 in the compression limiter 100 that present embodiment provides, Gain selector 140 divides
It is not connect with gain regulation module 110 and clipping control module 130, Gain selector 140 is according to the first signal gain and second
Signal gain generates system signal gain, and compression limiter 100 realizes the compression clipping of input signal according to system signal gain.
In a specific embodiment, in synchronization, Gain selector 140 selects in the first signal gain and second signal gain
Lesser yield value compresses limiter 100 according to system signal gain and realizes input as the yield value in system signal gain
The compression clipping of signal.
According to the description in the first embodiment, it is known that occurring since clipping distortion to clipping distortion disappearing
During removing, compression limiter 100 is being eliminated by selecting the yield value in second signal gain as system gain value
During clipping distortion, the yield value of second signal gain is obviously less than the yield value of the first signal gain, in other words, though
So yield value of the first signal gain can also reduce during this, but reduced amplitude does not have the reduction amplitude of second signal gain
Greatly.In order to avoid the second output signal finally exported is too small, after clipping distortion elimination, clipping control module 130 can be controlled
Yield value in second signal gain gradually increases, and after the second signal gain reaches preset clipping yield value, no
It is further added by.In addition, the yield value of second signal gain can be always maintained at when there is not clipping distortion in the second output signal
Above-mentioned clipping yield value (at this point, clipping control module 130 will not adjust second signal gain)；In this process
In, if the amplitude of the second output signal is too small, compression limiter 100 can be adjusted by the first signal gain, directly
Reach clipping amplitude to its amplitude, selects the yield value pair in the first signal gain in Gain selector 140 in this case
Input signal amplifies operation (yield value of the first signal gain gradually increases but is less than above-mentioned clipping yield value).
Second of embodiment is improved, the third embodiment is obtained, as shown in fig. 6, in the present embodiment,
It include distortion detector 131 and the second sequence controller 132 in clipping control module 130, wherein distortion detector 131 and expansion
Sound module 120 connects, and the second sequence controller 132 is connect with distortion detector 131 and Gain selector 140 respectively.It is compressing
In 100 course of work of limiter, the second output signal that distortion detector 131 can persistently export public address module 120 is supervised
It surveys, sees whether clipping distortion occur.If distortion detector 131 detects that clipping distortion occurs in the second output signal, transmission is cut
Wave distortion signal is to the second sequence controller 132；Second sequence controller 132 receives the clipping distortion signal, immediately basis
Second output signal adjusts second signal gain (reducing the yield value of second signal gain), and second signal adjusted is increased
Benefit is sent to Gain selector 140.Then, if distortion detector 131 detects that clipping distortion eliminates in the second output signal,
It then sends clipping distortion and eliminates signal to the second sequence controller 132；Second sequence controller 132 receives the clipping distortion and disappears
After signal, (yield value for increasing second signal gain) can be equally adjusted to the second output gain, it finally will adjustment
Second signal gain afterwards is sent to Gain selector 140.
In a specific embodiment, as shown in fig. 7, the second sequence controller 132 is adjusted second signal gain
Process it is as follows:
When clipping distortion occurs in the second output signal, the second sequence controller 132 starts time C according to preset slicing
(there is time for eliminating to clipping distortion in clipping distortion, i.e., by the amplitude control of the second output signal in slicing amplitude when
Between), reduce the yield value of second signal gain.In actual operation, it is intended that the clipping distortion of appearance can be as fast as possible
Elimination, therefore herein, preset slicing starting time C would generally be shorter, only several milliseconds of even delicate grades.When second
When sequence controller 132 receives clipping distortion signal, time C can be started according to the preset slicing, be controlled rapidly
In slicing amplitude, and the yield value reduction speed of second signal gain is greater than the yield value reduction speed of the first signal gain,
During this, Gain selector 140 selects the yield value of second signal gain as the yield value of system signal gain.As for second
The yield value reduction speed of signal gain is related with the second output signal, slicing starting time C and slicing amplitude, can send out in real time
Changing does not give concrete values herein.In addition, from the figure we can see that, slicing starts time C will be much smaller than the starting time
(the first output signal is usually several milliseconds and arrives A beyond clipping amplitude to the time controlled in clipping amplitude, starting time A
A few tens of milliseconds).
Then, when the second output signal clipping distortion is eliminated, and the second sequence controller 132 is discharged according to preset slicing
Between D (amplitude of the second output signal is controlled into time in clipping amplitude from slicing amplitude) increase the increasing of second signal gain
Benefit value is until clipping yield value.It can be seen from the figure that the yield value of the first signal gain is constantly between on startup in A
Reduced state, and the yield value of second signal gain can first reduce (slicing starts in time C) and be further added by (slicing release time
In D), and in slicing release time D, it may appear that letter of the yield value of a bit of time second signal gain less than the first signal
Number yield value (Gain selector 140 selects the yield value of second signal gain as system signal gain), later second signal
The yield value of gain is increased above the yield value of the first signal gain and is constantly in the state (increasing greater than the first signal gain
Beneficial selector 140 selects the yield value of the first signal gain as system signal gain), as shown in fig. 7, occurring until next time
The case where clipping distortion, clipping control module 130 are again adjusted second signal gain, are recycled with this.
The third embodiment is improved to obtain the 4th kind of embodiment, as shown in figure 8, in the present embodiment,
It include a variable gain amplifier 111, compression control amplifier 112, comparator 113 and first in gain regulation module 110
Sequence controller 114, wherein variable gain amplifier 111 is connect with Gain selector 140, compression control amplifier 112 with can
Variable-gain amplifier 111 connects, and comparator 113 is connect with variable gain amplifier 111 and compression control amplifier 112 respectively,
First sequence controller 114 is connect with Gain selector 140 and comparator 113 respectively.During the work time, variable gain first
Amplifier 111 amplifies input signal according to the system signal gain that Gain selector 140 exports, output the first output letter
Number；After compression control amplifier 112 receives first output signal, the first reference voltage Vref is adjusted immediately；
Then, the amplitude of the first output signal and the first reference voltage Vref are compared；Finally, the first sequence controller 114
The first signal gain is adjusted according to the comparison result of comparator 113, and by the first signal gain input gain selector adjusted
140。
Specifically, as shown in figure 9, in compression control amplifier 112: when the amplitude of the first output signal is less than compression
When threshold threshold value V1, compression control amplifier 112 draws high the first reference voltage Vref, and the first reference voltage Vref does not rise at this time
Effect, in this process compress limiter input signal is amplified and is exported, i.e., output signal (including first output letter
Number and the second output signal) it is linear with input signal；When the first output signal amplitude in compression threshold threshold value V1 and
When between clipping threshold threshold value V2, compression control amplifier generates the first reference voltage Vref according to preset compression ratio, to sound
Sound signal is compressed；When the amplitude of the first output signal is greater than clipping threshold threshold value V2, compression control amplifier is joined first
Voltage Vref constant control is examined when compressing 100 output violent change of limiter (amplitude of the second output signal is in clipping amplitude) pair
The voltage value answered carries out clipping to input signal.
Compression control amplifier 112 is after adjusting the first reference voltage Vref, and comparator 113 is with i.e. by first
The amplitude of output signal is compared with the first reference voltage Vref.Specifically, when the amplitude of the first output signal is greater than compression control
When the first reference voltage Vref that amplifier 112 processed exports, it is transmitted into starting time A and instructs to the first sequence controller 114；
When the amplitude of the first output signal is less than the first reference voltage Vref that compression control amplifier 112 exports, it is transmitted into and releases
Time B is put to instruct to the first sequence controller 114.
Then, in the first sequence controller 114: when the first sequence controller 114 is received into starting time A instruction
When, the first sequence controller 114 reduces the yield value of the first signal gain according to preset starting time A, by the second output
Signal controls in clipping amplitude；When the first sequence controller 114, which is received, to be instructed into release time B, the first timing control
Device 114 processed increases the yield value of the first signal gain according to preset release time B (generally in several hundred milliseconds by several seconds), the
One signal gain is as shown in Figure 7 with the variation of input signal.
Based on above description, in the present invention, by whether going out in distortion detector detection public address module (public address equipment)
Existing slicing, if there is then at once by the second sequence controller according to the starting time reduction second signal increasing of preset slicing
Benefit, and using the second signal gain after reduction as system signal gain at this time, achieve the purpose that elimination clipping is distorted.It is cutting
Wave distortion release after, immediately increase second signal gain, the second output signal is finally controlled carried out in clipping amplitude it is defeated
Out.To be eliminated in the second output signal automatically due to starting overlong time or since output loading becomes weight, supply voltage becomes
Public address module reduced dynamic range caused by when low, temperature such as gets higher at the application conditions variation and the clipping distortion occurred, improve and expand
The output sound quality of sound module, the user experience is improved.
4th kind of embodiment is improved to obtain the 5th kind of embodiment, as shown in Figure 10, in the present embodiment,
Compressing in limiter 100 further includes a slicing amplitude generator 150 connecting respectively with public address module and compression control amplifier.
During the work time, slicing amplitude generator 150 obtains the slicing amplitude of public address module in real time, and obtained slicing amplitude is sent out
It send to compression control amplifier；After compression control amplifier receives the slicing amplitude, according to the slicing amplitude received to ginseng
It examines voltage and makes corresponding adjustment, and then adjust the clipping amplitude in compression limiter 100.Such as Figure 11 and Figure 12, respectively work as expansion
When the dynamic range of sound equipment reduces (reduction of slicing amplitude), the relational graph between the second output signal and input signal, and pressure
The corresponding adjustment schematic diagram that contracting control amplifier makes reference voltage according to the first output signal and the slicing amplitude.It is specific next
It says, as shown in figure 11, when slicing amplitude reduces (such as figure is reduced to slicing amplitude a2 from slicing amplitude a1), compression control is amplified
First compression threshold threshold value V1 and the first clipping threshold threshold value V2 can be adjusted to the second compression door as shown in figure 11 by device first
Sill threshold value V1 ' and the second clipping threshold threshold value V2 ', and the second compression threshold threshold value compression threshold threshold value of V1 ' < first V1, second
The clipping threshold threshold value clipping threshold threshold value of V2 < first V2 '.Subsequent compression control amplifier is according to the second compression threshold adjusted
Threshold value V1 ' and the second clipping threshold threshold value V2 ' make corresponding adjustment to reference voltage.
Similarly with the 4th embodiment, the process that compression control amplifier is adjusted reference voltage specifically: when
When the amplitude of first output signal is less than the second compression threshold threshold value V1 ', compression control amplifier 112 is by the second reference voltage
Vref ' is drawn high, at this time the second reference voltage Vref ' it does not work；When the amplitude of the first output signal is in the second compression threshold threshold
When between value V1 ' and the second clipping threshold threshold value V2 ', compression control amplifier generates second with reference to electricity according to preset compression ratio
Vref ' is pressed, voice signal is compressed；When the amplitude of the first output signal is greater than the second clipping threshold threshold value V2 ', compression control
Amplifier processed is by the second reference voltage Vref ' constant control in compression 100 output violent change of the limiter (amplitude of the second output signal
In clipping amplitude) when corresponding voltage value.Based on above description, as shown in figure 12, in compression control amplifier to reference electricity
During pressure is adjusted, by the reduction of the first compression threshold threshold value V1 and the first clipping threshold threshold value V2, compression control is put
Big device reference voltage is adjusted therewith (the first reference voltage Vref is reduced to the second reference voltage Vref according to fixed ratio ',
To reduce the clipping amplitude of the second output signal (as shown in Figure 11 and Figure 14, from clipping amplitude VLIt is reduced to clipping amplitude
VL').It is consistent described in working principle and the 4th embodiment in subsequent comparator and the first sequence controller, herein
It does not repeat them here.
In addition, (relationship of input voltage and the second output voltage is as shown in Fig. 2, figure when the dynamic range of system is smaller
Output voltage in showing is the second output voltage here), it compresses in limiter to come in fact using the only algorithm with clipping function
Existing above-mentioned purpose, it is similar with foregoing description, during the work time, and after slicing amplitude generator detects slicing amplitude, pressure
Contracting control amplifier equally reduces its limiting threshold V according to fixed ratio, and the first reference voltage Vref reduces also according to fixed ratio, from
And the clipping amplitude of the second output signal is controlled with slicing amplitude in relatively-stationary ratio, such as Figure 14 also according to fixed than reducing
Shown, when slicing amplitude drops to a1 ' from a1, then clipping amplitude is therewith from VLIt is reduced to VL’。
The equivalent load access for the scaled down for including in slicing amplitude generator 150 is described in we below:
As shown in figure 13, it is specifically included in above-mentioned slicing amplitude generator 150: a PMOS transistor Q1, a NMOS crystal
Pipe Q2, an equivalent resistance R, the first divider resistance R1, the second divider resistance R2, third divider resistance R3, the 4th divider resistance R4
And amplifier W, wherein the grounded-grid of PMOS transistor Q1, drain electrode connect the one end of power supply, source electrode respectively with equivalent resistance R
And first divider resistance R1 one end connection；The grid of NMOS transistor Q2 connect power supply, source electrode ground connection, drain electrode respectively with equivalent electricity
Hinder one end connection of the other end and third divider resistance R3 of R；The other end of first divider resistance R1 is electric with the second partial pressure respectively
Hinder one end of R2 and the positive input terminal connection of amplifier；The other end of third divider resistance R3 is respectively with the 4th divider resistance R4's
The connection of the negative input end of one end and amplifier；The other end of second divider resistance R2 and the output end of amplifier connect；4th point
Input common mode voltage VCM in the other end access public address module of piezoresistance R4 (uses difference in the present invention in public address equipment
Output, the difference channel in slicing amplitude generator 150 and the public address equipment here share the same input common mode voltage, from
And obtain its slicing amplitude)；The output end of amplifier is connect with compression control amplifier.
Based on the description above to the equivalent load access in slicing amplitude generator 150, in a specific embodiment,
We carry out the diminution of equal proportion according to 1/1000 ratio to each device, if, PMOS tube original breadth length ratio is 100000,
NMOS tube original breadth length ratio is 50000；Then in the equivalent load access, PMOS tube breadth length ratio is 100, and NMOS tube breadth length ratio is
50.Meanwhile above-mentioned equivalent resistance is adjusted according to external actual loading adjustment, such as external 8 Ω (ohm) loudspeaker,
Then equivalent load is 8k Ω (kilohm)；For another example, external 4 Ω loudspeaker, then equivalent load is 4k Ω.In this embodiment,
The Application Range of the resistance value of one divider resistance R1, the second divider resistance R2, third divider resistance R3 and the 4th divider resistance R4
It is tens kilohms to several hundred kilohms, and this four divider resistances and amplifier W form an operational amplifier, obtain equivalent
The voltage at resistance both ends simultaneously amplifies output, finally controls amplifier for the output as slicing amplitude input dynamic compression
In 100.In this way, can be with slicing amplitude actual in dynamic following public address equipment, thus dynamic adjustment compression limit by the circuit
The clipping threshold threshold value of width device 100.Certainly, in other embodiments, mesh of the invention can also be realized using other ratios
, e.g., scaled down is carried out to each device according to 1/500,1/2000 equal proportion, this will not be repeated here.
Based on above description, in order to solve the problems, such as that differing too small with clipping amplitude by slicing amplitude causes, we are being pressed
It is provided with slicing amplitude generator 150 in contracting limiter, and the slicing amplitude of acquisition is sent to compression control amplifier 112,
And then adjustment of the realization to clipping amplitude.By slicing amplitude and the control of clipping amplitude in relatively-stationary ratio, to compress
Limiter 100 can smoothly elimination clipping be distorted, while will not cause other noises.
It should be noted that above-described embodiment can be freely combined as needed.The above is only of the invention preferred
Embodiment, it is noted that for those skilled in the art, in the premise for not departing from the principle of the invention
Under, several improvements and modifications can also be made, these modifications and embellishments should also be considered as the scope of protection of the present invention.
Claims (5)
1. a kind of compression limiter, which is characterized in that include: in the compression limiter gain regulation module, public address module with
And clipping control module, wherein
The gain regulation module exports the first output signal according to the input signal of the compression limiter；And according to described
The first signal gain of clipping is compressed in first output signal, feedback regulation for realizing the input signal；
The public address module is connect with the gain regulation module, and the public address module exports the gain regulation module
First output signal carries out power amplification, exports the second output signal；
The clipping control module, connect with the public address module, and the clipping control module is exported according to the public address module
The second output signal in the clipping distortion that occurs, feedback regulation for realizing input signal compression clipping second signal
Gain；
The compression limiter presses the input signal according to first signal gain and the second signal gain
Second output signal of the compression limiter output is controlled and is exported in clipping amplitude by shrinkage limit width；
Further include a Gain selector in the compression limiter, the Gain selector respectively with the gain regulation module and
The clipping control module connection, the Gain selector is according to first signal gain and the second signal Gain generating
System signal gain, the compression limiter realize the compression clipping of the input signal according to the system signal gain；
In synchronization, the Gain selector selects lesser in first signal gain and the second signal gain
Yield value is realized described defeated as the yield value in system signal gain, the compression limiter according to the system signal gain
Enter the compression clipping of signal；
It include a variable gain amplifier, compression control amplifier, comparator and the first timing in the gain regulation module
Controller, wherein
The variable gain amplifier is connect with the Gain selector, the system signal exported according to the Gain selector
Gain amplifies input signal, exports the first output signal；
The compression control amplifier, connect with the variable gain amplifier, according to first output signal adjustment first
Reference voltage；
The comparator is connect with the variable gain amplifier and the compression control amplifier respectively, and the comparator will
The amplitude of first output signal and first reference voltage are compared；
First sequence controller, connect with the Gain selector and the comparator respectively, first timing control
Device adjusts the first signal gain according to the comparison result of the comparator, and the first signal gain adjusted is inputted the increasing
Beneficial selector；
It further include a slicing being connect respectively with the public address module and the compression control amplifier in the compression limiter
Amplitude generator,
The slicing amplitude generator obtains the slicing amplitude of the public address module in real time, and the slicing amplitude is sent to institute
State compression control amplifier；The compression control amplifier is according to the slicing amplitude adjustment described first received with reference to electricity
Pressure, and then adjust the clipping amplitude in the compression limiter.
2. compression limiter as described in claim 1, it is characterised in that: include distortion detector in the clipping control module
With the second sequence controller, wherein
The distortion detector is connect with the public address module, and the distortion detector is for detecting the public address module output
The second output signal in whether there is clipping distortion；
Second sequence controller, connect with the distortion detector and the Gain selector respectively, when the slicing is examined
It surveys device and detects that clipping distortion occurs in second output signal, second sequence controller is according to second output signal
Second signal gain is adjusted, and second signal gain adjusted is inputted into the Gain selector.
3. compression limiter as claimed in claim 2, which is characterized in that
In second sequence controller:
When clipping distortion occurs in second output signal, second sequence controller starts the time according to preset slicing,
Reduce the yield value of the second signal gain；And within the slicing starting time, the gain of the second signal gain subtracts
Small rate is greater than the gain reduction speed of first signal gain；
When the second output signal clipping distortion is eliminated, second sequence controller according to preset slicing release time,
Increase the yield value of the second signal gain.
4. compression limiter as described in claim 1, which is characterized in that
In the compression control amplifier:
When the amplitude of first output signal is less than the first compression threshold threshold value, the compression control amplifier is by described
One reference voltage is drawn high；
When the amplitude of first output signal is between the first compression threshold threshold value and the first clipping threshold threshold value, the pressure
Contracting control amplifier generates the first reference voltage according to preset compression ratio；
When the amplitude of first output signal is greater than the first clipping threshold threshold value, the compression control amplifier is by described first
Reference voltage constant control corresponding voltage value in the compression limiter output violent change；
And/or
In the comparator:
When the amplitude of first output signal is greater than the first reference voltage of compression control amplifier output, it is transmitted into and opens
Time command is moved to first sequence controller；
When the amplitude of first output signal is less than the first reference voltage of compression control amplifier output, it is transmitted into and releases
Time command is put to first sequence controller.
5. compression limiter as claimed in claim 4, which is characterized in that the slicing amplitude generator is according to scaled down
Equivalent load access obtain the slicing amplitude；
It is specifically included in the slicing amplitude generator: a PMOS transistor, a NMOS transistor, an equivalent resistance, first point
Piezoresistance, the second divider resistance, third divider resistance, the 4th divider resistance and amplifier, wherein
The grounded-grid of the PMOS transistor, drain electrode connect power supply, source electrode respectively with one end of the equivalent resistance and described the
One end of one divider resistance connects；The grid of the NMOS transistor connect power supply, source electrode ground connection, drain electrode respectively with the equivalent electricity
The connection of one end of the other end of resistance and the third divider resistance；The other end of first divider resistance is respectively with described second
The connection of the positive input terminal of one end of divider resistance and the amplifier；The other end of the third divider resistance is respectively with described
The connection of the negative input end of one end of four divider resistances and the amplifier；The other end of second divider resistance and the amplification
The output end of device connects；The other end of 4th divider resistance accesses the input common mode voltage in the public address module；It is described
The output end of amplifier is connect with the compression control amplifier.
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