CN101771397B - Attenuation method and attenuator for linear continuous adjustable sound intensity - Google Patents

Abstract

The invention discloses a logarithmic attenuation method and an attenuator for linear continuous adjustable signals. The attenuator comprises a timer circuit, an attenuation quantity control signal generating circuit, and an audio circuit, wherein the timer circuit is used for generating a first pulse and a second pulse; the attenuation quantity control signal generating circuit is used for generating a first signal, a second signal and a changing process signal positioned between the first signal and the second signal; and the audio circuit is used for performing a multiply operation. The logarithmic attenuation method and the attenuator can accurately quantify the decibel or the logarithmic scale attenuation quantity of the attenuator by performing linear adjustment on the resistance value of a variable resistor.

Description

LINEAR CONTINUOUS is adjustable sound intensity decay method and attenuator

Technical field

The present invention relates to signal particularly the logarithmic decrement method and the attenuator of sound intensity signal, particularly, the present invention relates to LINEAR CONTINUOUS adjustable signal particularly the logarithmic decrement method and the attenuator of sound intensity signal.

Background technology

1834, weber found that the difference limen that stimulates is a linear function of the intensity of stimulation own, is referred to as Weber's law; That is to say that the animal reflection world is not each physical parameter absolute magnitude of reaction nature, but react their relative quantity, be i.e. variable quantity and ratio with reference to absolute magnitude.This law is applicable to each sensory system, and therefore the reflection of the psychophysical quantity of sensation is the logarithm that stimulates absolute magnitude and reference point ratio.The people stimulates the sensation (listen, look, smell, flavor, somesthesia etc.) of (like brightness, chemical molecular concentration, mechanical stimulus pressure etc.) intensity to describe by decibel (logarithm) to external world, as to intensity of sound being the sound intensity (I), describes with dB SPL:

$\begin{array}{cccc}I=10\lg \frac{E_1}{{\mathrm{<figure-callout\; id="0"\; label="E"\; filenames="H200810220728XE00022.png"\; state="\{\{state\}\}">E</figure-callout>}}_0}& \mathrm{or}& I=20\lg \frac{P_1}{{\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="H200810220728XE00022.png"\; state="\{\{state\}\}">P</figure-callout>}}_0}& \mathrm{dBSPL}\end{array}---\left(1\right)$

P wherein ₀, E ₀Being absolute acoustic pressure or the acoustic energy with reference to sound, is people's minimum impression value usually, P ₁, E ₁For measuring the absolute acoustic pressure or the acoustic energy of sound.

In order to be fit to human psychological feelings to nature; One maximum impression value is set usually; The rule of experiencing nature by the mankind is again carried out logarithmic decrement, often requires to be undertaken by the attenuation of decibel (dB) scale like the decay to audio signal or some other special sense signal (like brightness, chemical molecular concentration, mechanical stimulus pressure etc.).According to the definition of decibel (dB), with respect to natural stimulus intensity parameter, this is a kind of nonlinear change relation.

Traditional attenuator mainly contains following several kinds: 1, potentiometer attenuator, and through regulating the attenuation that a variable-resistance resistance is come regulated attenuator, can regulate continuously, but be difficult to come the quantitatively size of its attenuation of indication by decibel or logarithmic scale; 2, programmable attenuator utilizes the method for programming that the attenuation of attenuator is set, and can be provided with by any-mode, but must participate in by the variable elements device, and be unfavorable for user's manual control; 3, electrically controlled attenuator utilizes the variable resistance characteristics of PIN pipe to come signal is decayed, and great majority are applied in microwave frequency band, realize the impedance matching of deamplification easily, and shortcoming also is to be difficult to the quantitatively size of its attenuation of indication.

Therefore, the attenuator of the continuous linear regulation of a kind of ability by decibel or logarithmic scale attenuation is provided, in various instruments and instrument and the application, particularly application of household electrical appliances, to the audio signal decay with significant to signal attenuation.

Summary of the invention

The object of the present invention is to provide continuously attenuator and the method for linear regulation by decibel or logarithmic scale attenuation.

A kind of technical scheme of the present invention is achieved in that the logarithmic decrement method that the particularly continuous adjustable sound intensity signal of a kind of LINEAR CONTINUOUS adjustable signal is provided; It mainly may further comprise the steps: generate first pulse (promptly; Pulse Ts) and based on first pulse obtain first signal (that is the voltage u (0) of capacitor C H); Broad-adjustable second pulse of production burst (that is, pulse Tw) also obtains secondary signal (that is, the voltage u (Tw) of capacitor C H) based on second pulse, and wherein, secondary signal is to decay gradually from first signal to form; And, first signal that will arrange according to sequential, be between first signal and the secondary signal change procedure signal and secondary signal as the attenuation control signal (that is, Pc) with the signal of input (for example audio signal, i.e. p _i(t)) thus carry out this signal of multiplying logarithmic decrement (audio signal).

Particularly, thus the attenuation of pulse duration linear regulation signal (like audio signal) that can be through regulating second pulse.

Particularly, may further include the step of before carrying out multiplying, the attenuation control signal being proofreaied and correct.

Another kind of technical scheme of the present invention is achieved in that provides a kind of adjustable sound intensity decay device of LINEAR CONTINUOUS that adopts the inventive method, and it comprises: the timer circuit that is used to generate first pulse and second pulse; Generate first signal, be in change procedure signal and the attenuation control signal generation circuit of secondary signal between first signal and the secondary signal according to sequential based on first pulse and second pulse; And the circuit (for example voicefrequency circuit) that is used to carry out multiplying.

Particularly, timer circuit can comprise timer (X1) that can generate second pulse and the variable resistor (W1) that can regulate the pulse duration of second pulse.

Particularly; The attenuation control signal generation circuit can comprise multiway analog switch (U1) and electric capacity (CH), and multiway analog switch produces first signal arranged according to sequential, is in change procedure signal and secondary signal between first signal and the secondary signal based on first pulse and the second pulse control capacitance.

Particularly, first signal, the change procedure signal and the secondary signal that are between first signal and the secondary signal can be voltage signal, and the attenuation control signal generation circuit further comprises the correcting circuit that voltage signal is proofreaied and correct.

Particularly, correcting circuit can be variable-gain amplification circuit, and variable-gain amplification circuit comprises variable resistor (W2), and its correction voltage and product of parameter k that is used to regulate the voltage of initial time electric capacity is 1.

Particularly, parameter k can be made as: k=0.1V ^-1

Particularly; Circuit (like voicefrequency circuit) can comprise multiplier chip; Multiplier chip comprises two inputs and an output, and two inputs are distinguished receiving attenuation amount control signal and signal (like audio signal), the signal (like audio signal) that output output has decayed.

Beneficial effect of the present invention is following:

As everyone knows, the resistive of nerve cell and capacitive character have determined its electric response characteristic.According to the electrical characteristics of nerve cell, the present invention provides the logarithmic attenuator of the adjustable sound intensity of a kind of LINEAR CONTINUOUS or other signal.This attenuator is accomplished with simple capacitance resistance loop, through variable resistor (w ₁) LINEAR CONTINUOUS change to regulate an attenuation by decibel (dB) relation; (CH) is operated in charging, discharge and hold mode respectively by certain sequential with electric capacity; Produce a width with timer and be proportional to variable resistor (w ₁) pulse (T _W) stop the discharge process of electric capacity (CH), and make electric capacity (CH) voltage remain u (T _W), this voltage is as the attenuation control voltage of circuit, thus realization is through variable resistor (w ₁) continuous linear change come attenuation by decibel or logarithmic relationship regulated attenuator.

An outstanding advantage of the present invention is decibel or the logarithmic scale attenuation that can come the accurate quantification attenuator through variable-resistance resistance of linear regulation.

Another one advantage of the present invention is that described linear regulation is continuous rather than discrete.

The present invention imitates the auditory center neuron can or claim the relation that the time-delay reflection stimulates intensity of sound with the action potential generation time; According to the electric response characteristic of nerve cell, provide a kind of LINEAR CONTINUOUS adjustable implementation method and circuit model by decibel or logarithmic decrement signal attenuator.

Below in conjunction with accompanying drawing and embodiment, further specify the present invention, but the present invention is not limited to these embodiment, any on essence spirit of the present invention improvement or substitute, still belong to scope required for protection in claims of the present invention.

Description of drawings

Fig. 1, RC parallel circuits.

The work schedule sketch map of Fig. 2, RC circuit of the present invention.

Fig. 3, LINEAR CONTINUOUS of the present invention is adjustable sound intensity decay device are implemented circuit diagram.

Fig. 4, of the present invention one about audio signal attenuation and variable resistor w ₁The sketch map of resistance relation.

Embodiment

The inventor finds in to the auditory center Study on Mechanism: the auditory center neuron can or be claimed the time-delay intensity of reflection stimulation sound well with the action potential generation time, and this reaction relation is based on neuronic capacitive character and ohmic electric response characteristic.Therefore; The present invention is directed to faced in the adjusting of above-described variable attenuator by decibel or logarithmic scale attenuation can not the adjustable problem of LINEAR CONTINUOUS; Use for reference the electric response characteristic of nerve cell, provide a kind of LINEAR CONTINUOUS adjustable implementation method and circuit model by the attenuator of decibel or logarithmic decrement amount.

The attenuator by decibel or logarithmic decrement amount that this LINEAR CONTINUOUS is adjustable comprises three functional modules, promptly by logarithmic decrement module, linear regulation module and the multiplying module of decibel, is realized by following three processes:

1, presses the logarithmic decrement of decibel.For RC parallel circuits shown in Figure 1, if its initial voltage is u (0), then the voltage u (λ) at λ moment electric capacity two ends is expressed as formula (2)

u(λ)＝u(0)e ^-λ/τ(2)

Wherein τ=RC is the time constant of circuit, and formula (2) can be done following distortion:

$\&DoubleLeftRightArrow;\ln \frac{u\left(\mathrm{\&lambda;}\right)}{u\left(0\right)}=-\frac{\mathrm{\&lambda;}}{\mathrm{\&tau;}}---\left(3\right)$

$\&DoubleLeftRightArrow;\lg \frac{u\left(\mathrm{\&lambda;}\right)}{u\left(0\right)}=-\frac{\mathrm{\&lambda;lge}}{\mathrm{\&tau;}}$

$\&DoubleLeftRightArrow;I=20\lg \frac{u\left(\mathrm{\&lambda;}\right)}{u\left(0\right)}=-\frac{20\mathrm{lge}}{\mathrm{\&tau;}}\mathrm{\&lambda;}\&ap;-\frac{8.686}{\mathrm{\&tau;}}\mathrm{\&lambda;}\left(\mathrm{dB}\right)---\left(4\right)$

Known by formula (1): the strong or gain than contrast signal represented in positive sign, and negative sign is represented than a little less than the contrast signal or decay; When acoustic pressure is converted into the electricity variation; Represent acoustic pressure with voltage; Promptly have db-loss amount (I) equal formula (4) can be expressed as λ constantly the voltage u (λ) at electric capacity two ends compare initial voltage (u (0)) and be attenuated

and that is to say; The db-loss amount of electric capacity voltage is directly proportional with capacitor discharge time (λ), is inversely proportional to the time constant (τ) in capacitance resistance loop; Wherein λ, τ can be arbitrary value; τ=RC, R and C also can corresponding values.Therefore, select specific db-loss amount output, as long as select RC tank capacitance voltage under the special time.Its time is selected by following linear regulation module completion.

2, linear regulation.Selected RC loop discharge time, also just selected the db-loss amount of output.For setting seclected time, can select timer circuit, also can realize by other circuit or method.This circuit mainly is made up of timer, variable resistor and electric capacity, is used to produce the pulse that a commutator pulse width (Tw) is directly proportional with variable resistor (w).So, electric capacity special time λ then can be set by variable resistor (w) through pulse width (Tw):

λ→Tw∝w (5)

3, multiplying.That exported through process 1 is the voltage u (λ) that RC circuit capacitance two ends have been attenuated.For realizing to arbitrary input p _i(t) attenuation can adopt an additional multiplier circuit completion that variable gain amplifier is arranged.Can know by formula (4) in the process 1, $u\left(\mathrm{\&lambda;}\right)={10}^{\frac{I}{20}}\&times;u\left(0\right)={10}^{-\frac{8.686}{20\mathrm{\&tau;}}\mathrm{\&lambda;}}\&times;u\left(0\right),$ If the product factor of multiplier is k, the multiplication factor of variable gain amplifier is A, and the output after amplifying is p corresponding to front end through the input u of RC (λ) _c(λ)=Au (λ).Therefore, the output p after multiplying _o(t) can be expressed as:

$p_o\left(t\right)={\mathrm{kp}}_c\left(\mathrm{\&lambda;}\right)p_i\left(t\right)=\mathrm{kAu}\left(\mathrm{\&lambda;}\right)p_i\left(t\right)=\mathrm{<figure-callout\; id="1"\; label="kA"\; filenames="H200810220728XE00021.png"\; state="\{\{state\}\}">kA</figure-callout>}10^{-\frac{8.686}{20\mathrm{\&tau;}}\mathrm{\&lambda;}}u\left(0\right)p_i\left(t\right)---\left(6\right)$

Be set to kAu (0)=1 like circuit system, then system is output as:

$p_o\left(t\right)={10}^{-\frac{8.686}{20\mathrm{\&tau;}}\mathrm{\&lambda;}}{p}_i\left(t\right)$

So, the attenuation of this circuit attenuation factor can be represented by the discharge time of RC circuit:

$I=20\lg \frac{p_o\left(t\right)}{p_i\left(t\right)}=20\lg \frac{u\left(\mathrm{\&lambda;}\right)}{u\left(0\right)}=-\frac{8.686}{\mathrm{\&tau;}}\mathrm{\&lambda;}---\left(7\right)$

Therefore, thus come by decibel or logarithmic decrement input signal with the multiplier computing discharge time (λ) of the variable resistor control RC circuit that this system can be through the linear regulation timer.

Based on above principle, in order to realize the linear regulation method of decibel or logarithmic decrement amount, variable attenuator provided by the invention is characterised in that and comprises:

The additional multiplier circuit that variable gain amplifier is arranged: it comprises two inputs and an output, and one in the input is input audio signal, another one input attenuation amount control signal, the voice signal after the output output attenuatoin.The relation of the input and output of this circuit should satisfy formula (6), and need be adjusted to 1 to the product kAu (0) of the initial value of attenuation control signal and coefficient k.Voicefrequency circuit of the present invention realizes with a multiplier circuit, also selectablely realizes with other similar circuit; The adjusting of the initial value of attenuation control signal and the product of coefficient k realizes with the correcting circuit of a band variable gain amplifier (A).

An attenuation control circuit: this circuit is a RC circuit by analog switch control, and it is operated in charging, discharge and hold mode respectively by certain sequential.The working timing figure of this circuit is as shown in Figure 2, abscissa express time among the figure, and ordinate is represented the voltage at electric capacity two ends, and beginning discharging time with electric capacity was 0 moment, and applying a width for before a control end of analog switch in 0 moment is T _SPulse makes electric capacity be operated in quick-charge state, pulse T _SCan provide also and can provide by key circuit, at pulse T by other circuit _SElectric capacity charging finishing voltage remains on u (0) (being generally VCC), pulse T before finishing _STriggering a width when finishing is T _WPulse, this pulse puts on another control end of analog switch, makes electric capacity be operated in discharge condition, pulse T _WFinish the back capacitor discharge and stop, and remain on u (T _W).According to formula (4) and (5), the width T of this pulse _WI is directly proportional with attenuation, that is, and and can be through regulating impulse width T _WCome the logarithmic attenuator attenuation I of linear regulation audio frequency decibel or other signal.

A timer circuit: this circuit major function is that pulse width T is set _W, mainly realize by 555 timer circuits, also can realize timer output pulse width T by other similar circuit _WCome linear regulation by a variable resistor, therefore, this variable-resistance resistance is directly proportional with the attenuation I of signal db-loss device.

As shown in Figure 3, for of the logarithmic attenuator of the audio frequency decibel of linear regulation of the present invention or other signal implements circuit diagram, this circuit diagram comprises:

The attenuation control signal generation circuit: this circuit mainly is made up of a multiway analog switch U1, capacitor C H, resistance R 1 and R2; The input 2Y0 of U1 is unsettled, 2Y1 meets power supply VCC, 2Y2 through resistance R 1 ground connection through resistance R 2, and the output 2C of U1 meets capacitor C H.When the control end A of U1 is high, B when low, analog switch 2Y1～2C conducting promptly is equivalent to capacitor C H to meet power supply VCC through resistance R 2, and electric capacity is recharged, and the value of R2 is very little usually, and CH is charged to VCC in very short time; When the control end A of U1 be low, when B is high; Analog switch 2Y2～2C conducting promptly is equivalent to capacitor C H through resistance R 1 ground connection, and electric capacity is by the discharge of the relation shown in the formula (2); As R1=8.686k Ω in the special case circuit of the present invention; CH=1 μ F, τ=R1CH=8.686ms then, but the resistance R 1 that can not ignore among the present invention also can be selected other values with capacitor C H; When the control end A of U1 is low, B when low, analog switch 2Y0～2C conducting, it is unsettled promptly to be equivalent to capacitor C H, and capacitance voltage is in hold mode.Therefore, as long as the level of control end A that analog switch U1 is set by certain sequential and B just can make capacitor C H work in charging, discharge and the state of maintenance, thereby produce required attenuation control signal.

Timer circuit: this circuit is mainly by 555 timer X1, variable resistor W ₁And capacitor C ₂Form, being used to produce a width is T _WCommutator pulse, T _WValue can represent by formula (9):

T _W＝1.1W ₁C ₂ (9)

Can be through regulating variable resistor W ₁Come to change linearly pulse width T _W555 timer X1 are by control impuls T _STrailing edge trigger control impuls T simultaneously _SAlso be the control signal of the control end A of analog switch U1, the pulse T of timer circuit generation simultaneously _WBe the control signal of the control end B of analog switch U1, therefore, the work schedule of the control end A of analog switch U1 and the control signal of B can be described as: at first, give pulse T _S, at this moment the control end A of U1 is that high level, B are low level, analog switch 2Y1～2C conducting, and capacitor C H quickly charges to VCC; Then, pulse T _SFinish the back trailing edge and trigger timer circuit generation pulse T _W, at T _WThe control end A of U1 is that low level, B are high level during this time, analog switch 2Y2～2C conducting, and capacitor C H is by the discharge of the relation shown in the formula (2), to T _WConstantly stop discharge; Then, the control end A of U1 is that low level, B are low level, the unsettled and sustaining voltage u (T of capacitor C H _W) constant, this voltage is adjusted into this voltage through correcting circuit and is the attenuation control signal.

Voicefrequency circuit: this circuit mainly is made up of a multiplier chip, and its two input variables are respectively attenuation control signal p _C(λ) with audio signal p _i(t), output u _oCan be expressed as:

p _o(t)＝kp _c(λ)p _i(t)(6)

Wherein parameter k confirms the parameter k=0.1V in the circuit of the present invention by the peripheral component of multiplier ^-1

Correcting circuit: this circuit is a variable-gain amplification circuit, and its multiplication factor does $A(A=1+\frac{w_2}{R5}),$ Mainly by amplifier U4, variable resistor w ₂Form its input u (T with resistance R 5 _W) and output p _CRelation represent with formula (10):

$p_C\left(\mathrm{\&lambda;}\right)=\mathrm{Au}\left(T_W\right)=(1+\frac{w_2}{R5})u\left(T_W\right)---\left(10\right)$

The effect of this circuit is exactly to adjust variable resistor w ₂Make voltage (the correction voltage p of u (0)=VCC) of initial time capacitor C H _C(λ) product with parameter k is 1, that is:

$\mathrm{kAu}\left(0\right)=k(1+\frac{w_2}{R5})u\left(0\right)=1---\left(11\right)$

Therefore, convolution (8) and formula (9), attenuator of the present invention has been realized the linear regulation of audio signal by decibel or logarithmic scale attenuation through after the verification, suc as formula (12):

w ₁→T _W→λ→I (12)

As shown in Figure 4, this is a logarithmic decrement amount and a variable resistor w about audio signal or other signal of the present invention ₁The sketch map of resistance relation.Abscissa among the figure is variable resistor w ₁Resistance, ordinate is the decibel value (dB) of attenuation.As can be seen from the figure audio signal attenuation and variable resistor w ₁The relation curve of resistance be a straight line through zero crossing, this further specifies can be through being provided with variable resistor w ₁Resistance come continuous linearity that decibel (dB) attenuation of attenuator of the present invention is set, this regulative mode is more accurately more flexible than the audio frequency attenuator of being made up of resistor network or additive method.

Claims (9)

1. the logarithmic decrement method of a LINEAR CONTINUOUS adjustable signal comprises:

(1) generates first pulse (Ts) and obtain first signal (u (0)) based on said first pulse;

(2) broad-adjustable second pulse of production burst (Tw) and obtain secondary signal (u (Tw)) based on said second pulse, wherein, said secondary signal is to decay gradually from said first signal to form; And

(3) thus said first signal that will arrange according to sequential, be in change procedure signal and said secondary signal between said first signal and the said secondary signal are carried out the said input of multiplying logarithmic decrement as the signal of attenuation control signal and input signal.

2. the logarithmic decrement method of LINEAR CONTINUOUS adjustable signal as claimed in claim 1, wherein, thus the logarithmic decrement amount of the signal of the said input of pulse duration linear regulation through regulating said second pulse.

3. according to claim 1 or claim 2 the logarithmic decrement method of LINEAR CONTINUOUS adjustable signal wherein, further is included in and carries out the step of said attenuation control signal being proofreaied and correct before the said multiplying.

4. the logarithmic attenuator of the LINEAR CONTINUOUS adjustable signal of the said method of one of an employing such as claim 1-3 wherein, comprising: the timer circuit that is used to generate said first pulse and said second pulse; Generate said first signal, be in change procedure signal and the logarithmic decrement amount control signal generation circuit of said secondary signal between said first signal and the said secondary signal according to sequential based on said first pulse and said second pulse; And the circuit that is used to carry out said multiplying.

5. the logarithmic attenuator of LINEAR CONTINUOUS adjustable signal as claimed in claim 4, wherein, said timer circuit comprises timer (X1) that can generate said second pulse and first variable resistor that can regulate the pulse duration of said second pulse.

6. the logarithmic attenuator of LINEAR CONTINUOUS adjustable signal as claimed in claim 5; Wherein, Said attenuation control signal generation circuit comprises multiway analog switch (U1) and electric capacity (CH), and said multiway analog switch is controlled said electric capacity based on said first pulse and said second pulse and produced said first signal arranged according to sequential, is in change procedure signal and said secondary signal between said first signal and the said secondary signal.

7. the logarithmic attenuator of LINEAR CONTINUOUS adjustable signal as claimed in claim 6; Wherein, Said first signal, the change procedure signal and the said secondary signal that are between said first signal and the said secondary signal are voltage signal, and said attenuation control signal generation circuit further comprises the correcting circuit that said voltage signal is proofreaied and correct.

8. the logarithmic attenuator of LINEAR CONTINUOUS adjustable signal as claimed in claim 7; Wherein, Said correcting circuit is a variable-gain amplification circuit; Said variable-gain amplification circuit comprises the second adjustable resistance, and its correction voltage and product of parameter k that is used to regulate the voltage of the said electric capacity of initial time is 1; Wherein, said parameter k is made as: k=0.1V ^-1

9. like the logarithmic attenuator of the described LINEAR CONTINUOUS adjustable signal of one of claim 4-8; Wherein, The circuit of said execution multiplying comprises multiplier chip; Said multiplier chip comprises two inputs and an output, and said two inputs receive said attenuation control signal and input signal respectively, and said output is exported the signal of logarithmic decrement.

Images