SU587600A1 - Device for automatic gain control - Google Patents

Description

one

The invention relates to radio engineering and can be used in systems for automatically adjusting the output signal level.

A device for automatic gain control is known, comprising a sequentially adjustable amplifier, a detector, a gate node, a threshold node and an adjustable pulse expander, as well as a drive, which is connected to the control input of the adjustable amplifier, and a synchronizer connected to the gate input of the gate element. ij,

However, such a device does not provide a simultaneous change in the duration and Shüplipudy pulses in the feedback circuit, which leads to a decrease in speed.

The purpose of the invention is to increase speed.

For this, in the device for automatic gain control, a zero-order extrapolator is turned on between the output of the gate element and the drive input, the reset input and the clock input of which are connected respectively to the outputs of the adjustable pulse expander and the synchronizer.

and the output is additionally equipped with a control input of an adjustable pulse expander.

FIG. 1 shows the structural electromotive scheme of the proposed device; Fig. 2 is a timing diagram explaining its operation.

The device for automatic gain control contains connected in series regulating the ly amplifier 1, the detector 2, the strobe element 3, the threshold node 4, the adjustable pulse expander 5, as well as the drive 6, the output of which

5 connected to; input control of adjustable amplifier 1, and synchronizer 7 connected to the control input of the gate element 3, between the output of which and input of accumulator 6, includes a zero-order extrapolator 8, the reset input and clock input of which are connected respectively to the outputs of the adjustable expander of 5 pulses and synchronizer 7,

5 and the output is additionally with a control input of an adjustable expander of 5 pulses.

The device for automatic gain control works as follows. An additive mixture of the pulse signal and noise, amplified by amplifier 1 and demodulated by detector 2, is fed to the input of the gate element 3, which samples the voltage of the noise coming from the exit of detector 2 at certain times of the signal between the pulses of the signal, the gate element 3 is set by a synchronizer 7. The voltage pulses of noise samples (Fig.), Exceeding the response voltage of the threshold node 4 {tf under) Form voltage amplitude-normalized voltage pulses (Fig. 2, b) at its output, which An adjustable spreading spreader 5 is pulsed. In accordance with the change in the noise level, J4ac current and duration of the pulses generated by the adjustable spreader 5 pulses (Fig. 2, c) vary, the frequency of the following pulses is in the range from zero to the gating frequency, and the duration is from zero to the value of the period value of the sampling pulses and synchronizer pulses of the synchronizer 7. The voltage of the noise samples from the output of the gate element 3 is fed to the signal input of the extrapolator 8, / to the clock input of which such as are for pulses synchroniser 7, while the reset input -.impulsy voltage generated by direct regulk expander 5 pulses. The output blocking of the extrapolator 8 (Fig. 2, d), acting on the control input of the adjustable pulse spreading device 5, controls the duration of the output pulses, ensuring that the extrapolator 8 resets the accumulated voltage to the end of each clock pulse of the synchronizer 7.

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Claims (2)

Entry Thus, the extrapolator 8 generates voltage pulses (see Fig. 2, d), the amplitude and duration of which are proportional to the noise level at the detector output 2. The accumulator 6 from the pulse sequence of the voltage of the extrapolator 8 allocates a constant component that acts on the amplifier 1 so that the noise level at its output does not exceed a predetermined threshold value. Such a device allows to increase the speed and significantly increase the duty cycle of the noise sampling pulses. Apparatus of the Invention A device for automatic gain control comprising an adjustable amplifier connected in series, a detector, a gate element, a threshold node and an adjustable pulse expander, as well as: Accumulate, the output of which is connected to the control input of the adjustable amplifier, and a synchronizer connected to the control input of the gate element, which is distinguished by the fact that, in order to improve speed, between the output of the gating element and the drive input is included a zero zero The order, the reset input and the clock input of which are connected respectively to the outputs of the adjustable pulse expander and the synchronizer / and the output is additionally connected with the control of the input of the adjustable pulse expander. Sources of information taken into account in the examination:, 1. USSR Copyright Certificate No. 497711, cl. H, 1974. R r