CS198257B2 - Connection for automatic control of level of tone frequences devices with automatic alteration of the reverse regulation time constant - Google Patents

Abstract

The time constant control, for audio equipment with automatic gain control, increases the feedback time constant of the control loop to its greatest value (a few minutes) once the input signal has appeared. It is maintained at this value until a given delay time (1-5 sec) has elapsed. The time constant is then changed to a very short value (c. 1sec) provided that the output signal falls below a given reference level throughout the whole of the given delay time (due to a drop in input level). When the output falls below the given reference level the sensitivity of the AGC amplifier is increased again and the control loop's time constant is increased from its low value to its greatest value when the output is equal to a second reference voltage.

Description

SUMMARY OF THE INVENTION The present invention relates to a circuit for automatic level control of tone frequency devices with automatic change of the feedback constant.

Many solutions are known for tone frequency devices that operate with automatic level control. In the known solutions, the time constant of the feedback control Tv which is best suited to the requirements is adjusted mechanically or manually by the electronic switch.

Common to known solutions is that the occurrence or okamíbÍt ^ i ^ m increase of the regulated signal arises attempt to reduce překmt control, the effect of a control circuit, by implementing the smallest possible control time constant T _L to a minimum. This reaction rate is, moreover, an essential requirement when using automatic level control devices.

Roodd1 among the known solutions then lies in the rate of change of the gain for the disappearance or weakening of the input signal, i. for the duration of the time control constant Tv without the controlled variable. Ideally, the control override, i.e. more or less faithfully maintaining the input dynamics, can be approximated by the fact that the time constant of the feedback control Tv is infinitely large, but at least is chosen in the order of several tens of minutes.

Clearly, in the magnitude of the signal at the output, a dynamic co-response occurs as the magnitude of the signal at the input increases. Because the signal source level is marimmised and bound for each type of source, in practice, when connected to the signal source, the amplification of the automatic regulation of the amplifier level of the most likely greatest expected input signal is set. .

The real disadvantage of these solutions is that the rapidly increasing dynamic input volume (such as information coming from chat partners grouped at different distances from the microphone) cannot produce a more reasonable output signal throughout the duration if the duration is long the back-regulation time constants Th substantially exceeds the pause time Tsz lying mmz by changing the individual signal sources (s).

It is only possible to switch the device to a new signal source which is different from the previous one before the time TszS> Tj> has elapsed, ie it has to be taken care of (before switching) in order for the amplifier to regain its sensitivity.

In order to meet this requirement, automatic level control amplifiers have been developed which have only a few seconds lasting back time constant Tr '. If these devices are used, the back time control constant Tv must then be selected in the size Tr- ^ Tsz, V in this case, the signal levels that change rapidly at the input are output at approximately the same amplitude.

In such a shortening of the time constant of the back-regulation Tv, ie. Amplification quickly following signal magnitude must be accounted for with near-constant transient amplifier control and automatic level control, i.e. with harmful, disturbing transient amplification, and at times of Tsz pauses, with ever increasing noise in background / noise /. In general, shortening the time constant of Tv regulation to about one second is detrimental to the dynamic volume of individual words and syllables, which last about 100 mi li seconds / f ms, up to 1 s, ie disfigures the accent by representing speech properties.

Despite the above mentioned disadvantages, the described solution is still acceptable, suitable for informative transmission of the input signal and it can be connected without further measures to other signal sources with a lower intensity than the previous ones.

The object of the invention is to eliminate the disadvantages of the solutions described here, but their advantageous properties are, on the other hand, unified.

The circuitry of the invention offers a general direction for realizing circuit units that well equalize the feedback control constant Tv for each input signal change and which may have built-in tone control / amplification devices, Maanee signal recorders / baffling with different automatic level control.

The purpose of the invention is to fully maintain, in addition to the best transmission of macrodynamics, the microdynamics abating within a few seconds, and taking into account changes in signal source level and expected pause times Tsz to remove the strong background noise generated by distortion dynamics at pause times.

It is an object of the invention that the damping capacitor is connected to a level-dependent, time-delayed discharge current circuit, the control input of which is connected to an output connected.

The method according to the invention is practical, it is - with reference to the output level - switchable to the signal sources of any level without interference, while the microdynamics of the input signal is fully maintained and at the same time the signal sources 8 guarantee a relatively undistorted macrodynamics transmission. , definable only in wide time intervals.

The invention is based on the invention of an electronically controlled circuit which can be built into the control circuit of any automatically-controlled amplifier.

After the input signal is present, the circuit maintains the feedback constant of the control loop Tv of the control circuit in the constant state of the output signal for as little as possible a few minutes lasting the value of the primary feedback constant of Tv-control until the delay time To / 1-5 s has elapsed. / us after the attenuation of the input signal, which is independent of its instantaneous value. After the delay time elapses This is the primary time constant of the return control Tv- automatically changed to the secondary time constant of the return control Tv ₂ in a very short time (approx. 1 s) but only if the output signal does not decrease during the whole delay. as a result of decreasing the input signal applied to the input of amplifier 8 an automatically controlled level - below the level (about 6 dB) of a particular reference source. After the output signal falls below the level of the secondary reference source, the sensitivity of the automatically controlled level amplifier by the circuit is restored completely or to the extent necessary by the fact that the secondary timing feedback of Tv - which until this stage determined the change in gain rate , but not immediately, but within a short time (about 0.5 s), continuously to the value of the primary feedback constant Tv - the output signal amplitude becomes equal to and later exceeds the level of the secondary reference source.

J ^e s h ^o Dr. tli ^ ^{n, and} output it with him-^ u ^ n ^{- p} r ⁱ s dream ^ v ^ UPM ^ ^ g ^^ ^{- n} e ^k le ^sne p ^{from p} r ^{o Step} secondary sources refereečeírc , then the primary control constant time constant Tv- remains unchanged even after the delay time To.

The circuit according to the invention has the following advantages:.

can be connected at a constant output level in time sequence to signal sources of different levels;

- during the pause times Tsz that occur at the input signal B / р /, background noise is suppressed by constant gain;

The overall input signal is faithfully maintained if the output signal does not fall below the reference level of the secondary reference source / level 0 to -10 dB. However, at least the microdynamics occurring within a few seconds are maintained if the output signal amplitude is also less than the reference level of the secondary reference source after the delay time T0 has elapsed.

When using circuits operating according to the functional principle of the device according to the invention, in many practical cases / mutually beneficial partners, entertainment music, theatrical and concerts transmissions, recitation of prose texts and messages can be radio and television / deciding that the dynamics of the transmission are identical to the original and show almost no distortion, and that there are no noticeable electronic influences.

It will further be appreciated that the present invention will be further appreciated by reference to exemplary embodiments thereof, wherein both in the description and in the figures the duplex frequencies are designated P = 10.

In the drawings, Fig. 1 indicates the sweating according to the invention and its incorporation in the control circuit of an automatically controlled level amplifier; FIG. 2 shows a simplified embodiment of a sweat according to the invention based on passive semiconductor elements; FIG. 3 shows an embodiment of the circuit according to the invention based on active and passive semiconductors; FIG. 4 shows the level of the input signals B / p / and Bg / p / supplied to each other by the associated signal sources and the level of their input noise Zy / p / ^and Zg / p /; FIG. 5 shows the output signal K _R (p) and the noise level Zp (p), which is present in an amplifier with automatic level control, which operates with a shorter time constant of the reverse regulation Tr caused by the walls and the signal signals // p / and B2 / p / display capture ^^ гВ where the gain change without the system variable is 10 µB / is; FIG. 6 shows the output signal K _H (p) and the noise level (д / p) which is caused by the input of the signal sources and the input signals (p). and B? / p / u of an auto-level amplifier that operates with a longer time constant Tg - the illustration shows the increment at which the rate of gain change without a system variable is zero (T * -oo). Fig. 7 the output signal Kv / p / and the noise level Z v / p /, which are obtained in amplifiers with automatically controlled level, which lispdou the primary time constant of the reverse control Tv * and the secondary time constant of the reverse control TV2 and According to the invention, the illustration shows an attribute where the rate of change in gain without a controlled variable, depending on the functional phases, is either zero (Τν ^ - * ^{0 0} ) or 30 dB (Tv2). The illustration shows only the original true-to-life reproduction of microdynamics, constant gain in signal breaks up to the delay time To, and a rutdmitic transition to a new /2./pL· signal source

Giving microdynamics in case the level of the output signal Kv / p / exceeds the reference level of the secondary reference source Rg / p / does not require any particular display, therefore this possible functional phase has not been shown in the figure; in this case the identity of Kv / p / - Kg / p / occurs. ‘

They are well known in individual figures - characterized by help with individual solutions of rising trajectories of time connotations Tg ddregulooání - control interventions when the level of input signals B / p / and B2 / p / »is exceeded.

The time constraints T * of the re-regulation are taken as identical for all three cases considered. The output signals in Figures 6 and 5 are also shown in case T _R = To + T2 · Time required to change · Amplification amplifier A with automatically controlled level of · 30 dB is equally represented by the shorter time constant T _R and the secondary time constant of the feedback control Tv2 <

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The invention and the circuit blocks used to carry it out, as well as their functions, will be further explained with reference to FIG.

The input signal source B (p) controls an amplified level amplifier A consisting of an amplifier Yp / p /, a feedback network Yy / p /, and a differential circuit.

In the known solutions, the output signal K / p / amplifier A with automatically controlled level via the rectifier D - depending on the type of solution - receives a Yg / p / bass bass filter which is characterized by a long back time constant or a short time constant. reverse regulation; then - the output signal from amplifier A · - by means of the differential circuit · j is compared with the level of the primary reference source H j / p /. · From the filter output Vyj / bass, the signal is sent to the DC amplifier Yp / p / and from there to the control input SB of the amplifier A with an auto-controlled level, depending on the input signal level Bp / loop amplification Yg / p. (Yy) so that the output signal K (p) has an approximately constant value, irrespective of the level of the input signal B (р). .

The process described is evident from the invention. The decisive difference between the known solutions and the present invention is represented by a block diagaam between the rectifier P and the cross-linker Y (p). According to the invention, two signal paths are possible from the rectifier D.

The first signaling path is used when the output signal K (p) of the amplifier A with an automatically transient level following the generation of the input signal B (р) remains in a stationary state. In this case, the output signal of the rectifier D partly forms the primary error signal generated by the differential circuit j with the primary reference source

R / р /> on the other hand, the secondary error signal H., generated by the difference circuit K with the secondary reference source R ^ / p /. ·

Z obit. 1 it can be clearly seen that in this case the secondary error signal H has a logical level 1; in this way, a logic level 0 is applied to the product logic circuit H j via the inverter 1, the signal path leading to the linear suds t, and then to the wall nom the amplifier Y ^ / p / is in the closed state. In a corresponding manner, the bass-depth filter Yr1 / p / and then through the product finally to a stein-amplifier Y ^ / p / which excites the loop Yp / pZ, Yy / p / amplifier A automatically according to the input signal level

The primary filter Y 1 / p / bass bass is formed by a time constant on the one hand - in the case of an increase in the input signal B / p /. Hj doregulated, on the other hand - in the case of a control circuit which, after attenuation of the input signal B / p / without a controlled variable, is the primary time constant Tv / reverse regulation:

receives the error signal Hj on the lpg circuit to a linear control signal Sz / p / and thereby a controlled level on the control primary summator S_, controlling the output SB

Ai V _K 1 / p / - ------- ³ ----- ^{1 +} p ^T l where. A / is a constant dependent logic circuit .I called the error signal ^e Hj: on the type of bass bass filter. The open state of the product across the OR gate In pommcí · logic 1seconds árn-0o

H2 = 1 when / K / р // 2> / R ₂ / p // _a

H2 = 0 when / K / р // S /R./p//·

In this case, the other blocks shown in the diagram do not work.

If the input signal B ^ p / a · result in the output signal and Kp / zmeeni, přioom but the level of the output signal K / р / still greater than the reference level of the secondary reference source R./p/, ^and remains ₽ after the rectifier D the signal path and thus the character of the circuit unchanged regardless of the elapsed time. The amplitude change rate is determined by the primary time constant TV / i if /R./p// </ K / p // d / R / p //.

However, if the level of the input signal Bp / is such that there is an inequality / K / р // S /R./p// », ie if the peak value of the output signal K / p / · is below the reference level then, for the primary and secondary error signals R and H, the relation Hj = H. x 0 is in effect.

The logic level 0 of the secondary error signal H. receives an error signal - time l, whose output signal t, when compared in the differential circuit K / with the delay time T0, is applied to the inverter F. Inverter F implements the violent logic functions :

F = 0 if O <t á To, a

F - 1 if t> To.

9825 7

For the inverter, the error signal - time is valid:

t = 0 if = 1, a.

t> 0 if H ₂ = 0.

During the time t <That shows the output signal F mmniče logical 0 level, consequently has no influence, and the gate of the AND gate gets £ inverting due to the secondary error signal of H ₂ _ £ invertoren logic level 1; The logic product 8 / continues to close the signal path leading through the secondary bass filter Yr2 / p / to the linear sumper S and the DC amplifier Y __ / p /. ·

The gate of the logic product is open via the inverter I_2, which is controlled by the logic level 0 of the inverter F, and also in this case also keeps the information recorded by the primary filter Y___1 / p / bass depths. = 1, to the DC rectifier Yp (p).

Consequently, in this case, the rate of change of the gain of the control ring without the controlled variable is determined by the parameters of the secondary filter Y ^ 2 / p / bass bass

Y _K 2 / p / = ^A 2 ¹ + ₽ ^T L where A, is a constant depending on the filter type Y 2 / p / bass, and Tj is the time constant of the filter. Seconds time constant Tv? the reverse control of the control circuit itself is in this case TV2 <_ 'Tv _ ♦

Z / es of amplifier A with automatically controlled level can then increase in this function phase of the secondary back-regulation time constant until the amplitude of the output signal K / p / reaches the reference level of the secondary reference source R ^ / p / »

When the inequality is reached / K / p //> / К ₂ / р // / H ₂ becomes equal to 1 /, the ignition is reset to the phase characterized by the primary time constant of the return control, gate, logic product E / is consequently closed, logical AND gate E_ ₂ nappotí it open. The level of the output signal K / p / is in this case completely controlled, since / R ₂ / p // <ZR / p //.

If the rate of gain change is then determined by the primary time constant Tv / reverse control, then the level of the output signal k / p / can reach the level of full control only after another time has elapsed. This disturbing, harmful effect is eliminated with the / K compensating circuit,

At the moment when the inequality of / K / p //> / R? / P // applies as the output signal K / p / is increased, the jump between levels 0 - 1 activates the correlation circuit of the secondary error signal R that appears on the secondary differential circuit K ?. This changes the transmission properties of the primary filter Yr1 / p / bass depths in such a way that the rate of gain change is less than or equal to that of the gain change that dominates the phase of the secondary time constant TV2 of the back regulation. This state is maintained until ‘until the output signal K / p / reaches the signal level of the primary reference source, i.e., full control. This process takes place during a coupling time Tp = 100 to 500 ms. After this time the operation of the coppnoating circuit and the control of the DC amplifier Yp (p) goes unchanged through the gate £ 2 ', but now through the primary filter Yy 1 / p / bass bass.

Consequently, by sweating according to the invention, it can finally be achieved that, in accordance with the different current states of the block diagram, the delay time and the level of the secondary reference source R? / P / engage the gate of the logic product E / a. Ep depends on the input signal levels B / p / filters Y / 1 / р / and Yk ^ / p / bass depths, which are located in the control circuit of the amplifier A with automatically controlled level, depending on the assigned logic functions , between the three-way amplifier Y ^ / p / and the rectifier 'D.

The application of the invention in FIG. 2, which is made up of passive semiconductors, represents a simple embodiment of the basic invention. The parameters of this circuit are in some sense interdependent, i.e. this embodiment constitutes a compromise by which the advantages of the invention are realized, but the costs remain low.

When analyzing this circuit it is necessary to start from the condition * / R / p // / R? / P // _ Jjttížje špččowá

98257 the value of the output signal K / p / exceeds the level of the reference source R / p /, which is constituted by the base voltage - emitter diodes D1, D6, and in the open state, then they are two-way charge transported via rectifier diodes D1 and D2 to damping capacitor C1 i discharged as an oasis current through transistor T3. When the input signal Ъ / p / occurs or its level increases, the time constant of the modulation is I, - R C.

When the input signal B (p) is reduced, the primary time constant T 1 is the feedback control of the control. without the controlled value of the circuit, equal to the time during which, when discharging the many charges collected in the damping capacitor C1, the value of the sensing voltage, i.e. the condenser damping voltage, reaches the reference level of the primary reference source R / p / FIG

where R je is the input resistance of the DC amplifier Υ _ρ / ρ /, U of the capacitor C _{j of the} signal R / p / a is ^U C0 =% 5 * ^U D6 ^{+ U} ggQ, ie. is equal to the emitter current of transistor T3.

In the constant state of the output signal K / p /, a and C2 of the relation "IR"

Diode D4 does not lead, determined by primary time constant TR when input signal Blp / coil is attenuated

When input signal B / p is attenuated, the charge Q2 of capacitor C2 is discharged via a load resistor R2 with a time constant K2 ^G 2 '° of the delay time, reaching the voltage level ¹

C1 is the wall voltage that is applied before the input signal B / p / is attenuated at the voltage level at which the damping coil voltage begins. rate of change of gain control regulation.

CC2 »enclosed on diode D4, values needed for diode opening:

^For C2 _T o = RR ln

Obviously, in this case, the delay time To is also dependent on DC voltages and * 22 »ie * ultimately on the magnitude of the input signal Bp / and the variations in the delay time To - depending on the loop gain of the entire control circuit signal B / p / even reach 100%. In the open direction, diode D4 switches in parallel the damping sensors O and C2 and the load resistor R2, and the Ryyhhost of the gain change is then determined by the secondary time constant of your feedback control:

Learning

Tv, Tv ₂ = R ₂ C, ln -0 ^ "or Rg $> R2 and Cl $> C2. υ ,, / Το / is the voltage value recorded at time T 0 on the damping capacitor C1.

. The chamfer increases until the equality / K / p // = / R / р // occurs. Thereafter, the rate of change in gain is again determined by the primary time constant Tr of the feedback control.

Since the conductivity of the D1 diode in the open direction only ceases to exist in the case of this embodiment when using the impedance axis of the diode switch, the installation of the fault-compensating circuit ZK is abandoned. Its role is also fulfilled by diode D4.

FIG. 3 shows an embodiment of the present invention composed of active semiconductors.

In order to avoid diode circuit defects and to separate the time constant from one another, the circuit was built of transistors.

In Fig. 3, circuit elements that were also present on the obit · 2 and performed the same function there are marked with the same symbboy.

The circuit works as follows: When the supply voltage D _{T is} switched on - if at this point in time no input signal B / p / arrives at the automatically controlled level A amplifier input - the damping capacitor C3 is charged via the charging resistance R6, opening voltage

Un ^. Naa _и ч ^ i ,,. _л is the voltage, based on eal to r., which is required to open transistor T2. The primary reference source Ry (ρ) of the circuit is the same as in FIG. 2. The transistor T2 conducts and spins the damping capacitor C1 with a load resistor of Rg and Rg in parallel, shorting the damping capacitor C5. At the input point of the DC amplifier Y _p / р / the voltage is zero, in this way the transistor T3 is closed and the amplifier A with the automatically controlled level has maximum sensitivity. If the input signal of the session / К / р // 2> / R ^ / p // occurs, the switching transistor T1 is open, but the transistor T_2 is closed. In this case, the constant magnitude of the output signal K (р) is determined by the time constant T _T Si R ^ C ^.

Damping capacitor C5 is charged through resistor R2. until “U _c $.

Therefore, the time constant of the reverse control changes only from within the interval of about 0, ~ 0.5 s, from the value of Tv ₂ to the value of Tv ₁ , Cl C4 and Cl |

The switching transistor T1 is controlled by an output signal К / ρ / without a time delay. The charging resistor R6 tries to charge the damping capacitor C3j in the negative period of the output signal К / ρ / in the positive period of the signal when the switching transistor is opened. However, this charge is always completely discharged via the discharge resistor R5 and the damping voltage. capacitor C?> can never reach the voltage level ΰ _β 2ο »P ^oC needed to open transistor T2, R5 <$ R6, and in the tone frequency transmission band is the period of the control signal T / 2 <^ To,

That is. depends only on circuit parameters and Zener voltage U ?,

The rate of change in gain - independent of the time elapsed since the input signal attenuation - is as long as it takes for the primary time constant Tv of the feedback control to decrease the inequality level / К / ρ // 3> / R ₂ / p //.

The level of secondary reference source R ₂ / p / is determined necessary for opening the switching transistor T 1, voltage divider R ^ -R.

B / р / reduced to such an extent that it is / К / ρ // / R ₂ / p //, then charges the charging resistor R6 over a period of voltage levels that is

If the input delay signal To / 2-3 s / damping capacitor C3 to voltage value UTranistor T2 opens, “—UZU” “shorts the damping capacitor C5 and connects the load resistor R ₂ « ^ ^R 3 ^s ^ ^ит * ^с in parallel ^ ^т capacitor Cl.

As a result, during the delay T0 following the reduction of the input signal B (р), the gain is constant, but then rises with a rate of change of 20 to 30 dB / s, in accordance with the secondary time constant. К / ρ = // / R ₂ / P //. ^at this point, the switching transistor T1 opens again, while the transistor 12 closes.

The amplitude of the output signal К / ρ / is, depending on the level of the secondary reference source R ,, / p /, 3 to 6 dB below the level of full regulation.

Here, the compensation circuit ZK formed from the load resistor R2 and the damping capacitor CJ5 now intervenes so that - the compensation time is T, = R _o C ₂ ^and θθ ^ras ”the load resistor R2 attempts to charge the energy from the damping capacitors C1 and C4 into the damping capacitor. C5. In this way, the gain reaches very quickly, within 0.1 to 1 s, the values belonging to the full control level, and the feedback constant time is again the primary feedback constant time.

The functional diagrams shown in Figures 5, 6 and 7 need no particular explanation. It should only be noted that the figures show well the transient over-regulation values that occur when the input signal sources В ^ / p / а and ^ ^ / p / are raised or increased.

Giant. 6 illustrates that if a long feedback constant T ^ is used, the output signal Кц / p / does not completely reach the level of regulation without any intervention on the second signal source В / p /.

Claims (3)

SUBJECT OF THE INVENTION 1. Wiring for automatic level control of equipment, tone frequencies with automatic change of the back-regulation time constant, with an automatically controlled level amplifier connected between the input and output whose control input is connected to the DC amplifier output and the DC amplifier input is either directly, or via a resistor connected to a damping capacitor, the other terminal of which is connected to ground and a diode rectifier is connected between the wiring output and the DC amplifier input, characterized in that the damping capacitor (С1) is connected to a level dependent, time delayed discharge current circuit (VI, V2), whose control input is connected to the wiring output. Wiring according to claim 1, characterized in that the first level-dependent, time-delayed discharge current circuit (V1) comprises a further diode (DD) connected to a common diode terminal (D1, D2) of a rectifier, RC member connected by 8 the end of another diode (D3) and consisting of a parallel combination of capacitor (С2) and resistor (R2), the other end of which is grounded, a fourth diode (D4), which is connected to a damping capacitor (С1), and diodes / D //. , 3. The apparatus of claim 1, wherein the second level-dependent, time delayed discharge current circuit (V //) consists of a divider (R3, R // of the voltage connected between the output and ground) of an amplifier transistor (T1). and from a further damping capacitor (СЗ) from a second transistor (T2) and a third damping capacitor (С5), wherein the base of the boost transistor (T1) is connected to the center of the voltage divider (R3, R4) and the collector of the boost transistor (T1) on the one hand based on the second transistor (T2) and on the other on the second damping capacitor (22), the second outlet of which is grounded, while the collector of the second transistor (T2) is connected to the grounded one. a third damping capacitor (С5) and a resistor (R2) with an input (Q) of a DC amplifier.