SU1424126A2 - Device for protection against pulsed interference - Google Patents

Abstract

The invention relates to radio engineering. In relation to aut. St. No. 658747, the objective of the invention is to reduce the residuals of impulse noise (PI) with flat trailing edges at the device output. The protection device contains a delay delay 1, a breaker 2, a power amplifier 3, a limiter amplifier 4 with a large AGC time constant, a pulse detector 5, a driver (F) level, made in the form of a F 6 rectangular LU pulse of variable duration , amplifier 7 with adjustable limiting threshold, beat filter 8, beat detector 9, voltage shaping unit (BFN) 10 proportional to the slope of the falling front of the power source, and amplifier 11 with adjustable coefficient. gain When PIs appear larger than the set threshold on amplifier 7, F 6 accumulates an interrupting pulse expanded by an amount proportional to the control voltage from amplifier 11. This control voltage amplifier 11 generates detector signals at its inputs 9 and BFN 10. T. arr., F 6 produces impulse. the duration of which is equal to the duration of the PI, acting on the receiver, dct at any time. The goal is achieved by the introduction of BFN 10 and the binding of the bodies of I. The device according to Clause 2 of the file is characterized by the execution of Φ 6. 1 c.p. f-ly, 5 ill. g (f С

Description

dmg /

The invention relates to radio engineering and can be used as part of receiving devices operating under pulsed interference conditions.

The purpose of the invention is to reduce the residuals of impulse noise with flat back edges on the device input.

FIG. Figure 1 shows the structural electrical circuit of the impulse protection device; in fig. 2 is a structural electrical circuit of a level former made in the form of a rectangular impulse generator of variable duration; in fig. 3 shows a structural electrical circuit of an example implementation of a voltage shaping unit proportional to the steepness of the rear front of a pulsed disturbance; Fig. 5 - voltage plots that measure the operation of a level generator made in the form of a rectangular pulse generator of variable duration.

The device for protection against impulse noise contains a delay element 1, a breeder 2, a power amplifier 3, a limiting amplifier 4 with a large AGC time constant, a pulse Detector 5, a level former, full-power in the form of a former 6 for a rectangular impulse of varying duration , amplifier 7 with adjustable limiting threshold, beat filter 8, detector 9 biHIi, voltage shaping unit 10 proportional to the steepness of the falling edge of the pulse, amplifier 1I with adjustable gain.

A variable pulse shaper 6 includes a comparator 12, a delay line 13, an adder 14, a differentiating element 15, a valve 16, a pulse expander 17.

A voltage shaping unit 10 proportional to the steepness of the trailing edge of the impulse noise comprises a second delay line 18 and a quad indicator 19.

The protection device from impulse noise works as follows.

In the absence of impulse noise and in the presence of a signal and harmonic interference at the input of the device, the latter pass through the passband

the amplifier ive the ibe as a beat are extracted on the pulse detector 5, then pass through the filter 8 having the necessary frequency response and bandwidth. These oscillations are detected by detector 9 and in the form of Slowly varying voltage regulate the trigger threshold of amplifier 7 so that with increasing amplitude of the beat voltage, the trigger threshold of amplifier 7 and, therefore, the former 6 increases with the appearance of harmonic interference at the input of the device impulse is not developed. In this case, the useful signal from the input of the device to its output through the element 1, the speaker 2 and the power amplifier 3 passes without interruption and, therefore, is not distorted.

In the case of the appearance of a pulse noise exceeding the value of the automatically set threshold on the amplifier 7, the driver 6 generates a breaking pulse extended by a value proportional to the control voltage applied to its control input from the output of the amplifier 11.

The input of amplifier 1I is supplied with voltage from the output of detector 9. The control input of amplifier 11 is supplied with voltage from unit 10. The latter produces a voltage proportional to the rate of change of the falling edge of the impulse noise, i.e. the voltage at the output of the block 10 is directly proportional to the steepness of the trailing edge of the impulse noise. This voltage determines the gain of the amplifier 1-1.

Thus, the control input of the transmitter 6 from the output of the amplifier 11 receives a control signal, which learns the magnitude of the threshold of the amplifier 7 that exists at the moment, and the steepness of the trailing edge of the impulse noise. In accordance with the magnitude of this control signal, an impulse is produced at the output of the actuator 6, the duration of which is equal to the pulse impedance acting on the receiving path at any time point in time. The nature of the change time exceeding. values of impulse noise above the threshold at its different values and with different steepness of the rear edge of the room

The xoBoiTO pulse is shown in FIG. 4a and 6.

Consider the algorithm for forming the duration of the preemptive pulse at the output of the driver 6.

Proceeding from the condition that the blanking impulse that terminates the main path must be equal to the duration of the impulse noise, we can write (Fig. 46), Q

 MP

Chm

where C - the duration prereshshak tsego

impulse;

Cgy - the duration of the impulse noise above the threshold;

 - 3

the duration of the rear part

front of impulse noise below the threshold level.

A pulse of duration is produced by the comparator 12. Therefore, the task is to determine the duration / and the elongation by this value for efficiency. From FIG. 4 shows that

BM

l threshold,

. dU tg - -,

H

- control voltage on

output of block Yu; 35

- time delay line 18 block 10.

/ 1l and threshold

 eff -JU-

or

 Jj -Azipfrog K,

Where

TO

one

whether

Since the duration E is a constant value, it is necessary to know the value of d / li to determine Ij. This value can be determined using amplifier 11 with a variable (adjustable) gain. On one input of such an amplifier should be supplied voltage Ufiepcra, and on the other voltage iU,

Wuxi coefficient

voltage amplification),

/ lU

th, Q

15

20

25

thirty

35

40

45

5С

where K is the gain of the amplifier 1 1.

If we know the value of UpcfToro / U, we can determine the duration Γ by extending the duration, by Unopora / times, and then, by lengthening the duration 5j by the duration, we obtain the duration of the breaking pulse, equal to the duration of the impulse noise

From the beating detector 9, the voltage dU from the unit 10, which controls the gain of the amplifier I1, is fed to the input of the amplifier 11. The control input of the imaging unit 6 receives the voltage from the output of the amplifier 11, which determines the duration

Consider the work of shaper 6.

Plot FIG. 5a depicts a single impulse noise, and FIG. 5d blanking impulse, detected by the interference noise detection path in the prototype. From the comparison of the two diagrams, an uncompensated impulse noise balance is visible.

When the threshold of amplifier 7 is exceeded by impulse noise, the comparator 12 reverses a rectangular pulse with the duration Dg (Fig. 5c), KOTOpuflf through line 13 and the adder 14 enters the output of the imager 6 (Fig. 5c). The rear front differentiated by element 13 of this a pulse (fig. 5g) is fed through valve 16 to the input of the expander 17. The latter produces a rectangular pulse (fig. 5 J), the duration of which is determined by the output voltage from amplifier II and is equal according to the above described normalization:

her

H

and

pvrog

whether

This pulse through the second input of the adder 14 is fed to the output of the imaging unit 6 and complements 1 gy to the required value of the breaking pulse (FIG. 5 e). In order to prevent a gap between and the pulses entering the first and second inputs of the adder 1A, the delay time of the line 12 is chosen equal to the response time of the series-connected differentiating element 15, valve 16 and expander 17. This delay is taken into account when choosing the delay time of element 1.

An example of a specific implementation of block 10 is shown in FIG. 3. It includes a delay line 18 with a constant delay time f and a subtractor 19.

By means of block 10, the difference / JV of the values of the falling edge of the impulse noise is set apart from each other by the value of G. The delay time Ij is chosen taking into account that the slowly varying voltage of the harmonic interference (relative to the rapidly varying voltage of the impulse noise ) the output voltage of the unit 10 was about 4V, approximately zero.

Claims (2)

Invention Formula I. Device for protection against impulse noise on the author. St. No. 658747, characterized in that, in order to reduce the remainder of the impulse noise with flat falling edges at the output of the device, an amplifier with an adjustable coeff 2D1266 an amplifier, the input of which is connected to the output of the beating detector, and the output is connected to the control input of the level generator, made in the form of a square pulse voltage generator of variable duration, and a voltage shaping unit proportional to the slope of the falling edge 10 of the pulse interference, the output of which is connected to the control The amplifier has an adjustable laziness factor input, and the input is connected to the output of a pulse detector. 2. A device according to claim 1, characterized in that the variable width pulse shaper will contain a serially connected comparator whose input is the variable width pulse square shaper input, the delay line and the adder, the output of which is a square pulse shaper output variable duration, successively connected differentiating element. The valve and the pulse expander, the control input of the output pulse duration of which is the control input of the variable-width square pulse former, the output is connected to another input of the adder, and the input of the differentiating terminal is connected to the output of the comparator.  / g (puff 2 77 sri.e Unopetal ffaoootat O / npete Yy G. І1 . " ngpcte lU Type of