SU1697258A1 - Device for automatic gain control with digital control - Google Patents

Abstract

The invention relates to radio engineering, in particular, to gain control devices with automatic control, and can be used in radio receivers for various purposes. The purpose of the invention is to increase the speed and noise immunity. A discrete automatic gain control device with digital control contains a controlled quadrupole 1, an input 2 and an output 3 of a controlled quadrupole 1, a threshold element 4, the first counter 5. a reversible counter 6, a trigger 7. the first 8 and second 9 elements And, the second counter 10 the decoder 11, the strobe pulse generator 12, the first 13 and the second 14 outputs of the strobe pulse generator 12. The purpose of the invention is achieved by simplifying the device and changing the functional connections between the individual elements of the device. 2 Il.

Description

ate with

o you

but

00

The invention relates to radio engineering, in particular, to gain control devices with automatic control, and can be used in radio receiving devices for various purposes.

The purpose of the invention is to increase the speed and noise immunity.

FIG. Figure 1 shows a structural electrical circuit of a discrete automatic gain control (AGC) device with digital control; in fig. 2 - timing charts of the device.

A discrete AGC device with digital control contains a controlled four-port network 1, an input 2 and an output 3 of a controlled four-terminal network 1, a threshold element 4, the first counter 5, a reversible counter b, a trigger 7, the first 8 and the second 9 elements I, the second counter 10, a decoder 11, the strobe pulse generator 12, the first 13 and the second 14 outputs of the strobe pulse generator 12.

The device works as follows.

A sync pulse from the first output 13 of the strobe pulse generator 12 (Fig. 26) at the time of the appearance of the input signal (Fig. 2a) returns to its initial state trigger 7, a reversible counter 6 and a second counter 10. Since the direct outputs of the reversible counter 6 connected to the corresponding minor bits of the controlled quadrupole 1, and the inverse outputs of the first counter 10 are connected to the corresponding bits of the controlled quadrupole 1, then at this moment its gain is minimal. The direct output of the trigger 7 prohibits the passage of clock pulses from output 14 (Fig. 2c) of the generator 12 strobe pulser through the second element 9 and at the same time provides permission to pass these clock pulses through the first element 8 at the input of the second counter 10, because from the output of the decoder 11 also received permission. At the time of the passage of the clock pulses from the output 14 of the strobe pulse generator 12 to the second counter 10, the gain of the controlled quadrupole 1 is increased by large samples (Fig. 2d) until the signal amplitude exceeds the threshold threshold 4, At this moment the signal from the output of the threshold element 4 is fed to the counting input of the first counter 5, which, when there is an initial state of the clock counter from the output 14 of the gate clock generator 12, is reset to the initial state no, and only when there are no clock pulses at this input, counter 5 starts counting. After the first overflow of a given capacity of the first counter 5, which performs the role of a digital integrator, the signal is fed to the input of the reversible counter 6, which operates on addition, from the first output of which the pulse arrives

0 to trigger 7 and sets it to such an inverse state that its output prohibits further passage through the first element AND 8 clock pulses to the input of the second counter 10. At the same time, the gain of the controlled quadrupole 1 decreases in small increments (Fig. 2d) until the signal amplitude exceeds the threshold of the threshold element AND, and this

0 occurs in the interval between the sync pulse and from the output 14 of the strobe pulse generator 12. Further setting to the initial state of the second counter 5 by this sync pulse provides an increase in noise immunity, since it eliminates the possibility of the counterfeit of the counter 5 from accidental interference.

Passage of clock pulses from the output 14 of the generator 12 strobe pulses through

0, the second element AND 9 to the second input of the reversible counter 6 operating on the subtraction, in this case provides an increase in the gain in small increments when the input signal decreases for a certain time, which is determined by the repetition period of the clock pulses (Fig. 2b).

At the time of filling the second counter 10 at the output of the decoder 11 is formed.

0 is a signal that prohibits the passage of sync pulses (Fig. 2c) through the first element And 8, which corresponds to the maximum gain of the controlled quadripole 1.

five

Claims (1)

DETAILED DESCRIPTION A discrete automatic gain control with a digital control, comprising connected 0 is a sequentially controlled quadrupole, the input and output of which are, respectively, the input and output of the device, and the threshold element connected in series by the first counter and the reversible 5 counter, the direct outputs of which are connected to the corresponding control inputs of the lower bits of the controlled quadrupole, connected in series by a trigger, the first element I and the second counter, the inverse outputs of which connected to the corresponding inputs of the higher bits of the controlled quadrupole, the second element And, the output of which is connected to the subtractive input of the reversible counter, the strobe pulse generator, the first output of which is connected to the inputs of zeroing trigger, the reversible counter and the second counter, and the decoder, which differs that, in order to increase speed and noise immunity, the output of the threshold element is connected to the counting 0 the input of the first counter, the installation input and the forward trigger are connected respectively to the low-order output of the reversible counter and to the first input of the second element I, the second output of the strobe pulse generator is connected to the zero input of the first counter and the second inputs of the second element I, the inputs of the decoder are connected to inverse outputs of the second counter, and the output of the decoder is connected to the third input of the first element I. P l shm FIG. 2