SU1626388A1 - Device for protection against pulse interference - Google Patents

Abstract

The invention relates to radio engineering and can be used as part of radio receivers operating under impulse noise conditions. The purpose of the invention is to reduce the impulse noise balance with a gentle leading edge. The impulse noise protection device comprises the first delay element 1, the interrupter 2, the adjustable delay unit 3, the limiter amplifier 4, the pulse detector 5, the variable-width rectangular pulse shaper 6, the amplifier 7 with adjustable limiting threshold, the beat filter 8, the beat detector 9 , a voltage shaping unit 10 proportional to the steepness of the leading and trailing edges of the pulse interference, the amplifier 11 with an adjustable gain factor. The device allows the formation of a blocking pulse, taking into account the duration of the leading and trailing edges of the impulse noise, which ensures a reduction in the remainder of the impulse noise at the output of the device. 2 hp f-ly, 4 ill. (Ls

Description

about

Yu

Os OJ 00 00

1

The invention relates to radio engineering and can be used as part of radio receivers operating under impulse noise conditions.

The purpose of the invention is to reduce the remainder of the impulse noise with a gentle leading edge.

FIG. Figure 1 shows the structural electrical circuit of the impulse noise protection device; FIG. 2 shows a structural electrical circuit of a variable-width square pulse shaper; in fig. 3 is a structural electrical block circuit of adjustable delay; in fig. 4 - voltage plots, which describe the operation of the device.

The impulse noise protection device contains the first delay element 1, the interrupter 2, the adjustable delay unit 3, the limiting amplifier 4, the pulse detector 5, the variable-width rectangular pulse shaper 6, the limiting amplifier 7 with adjustable limiting threshold, the beat filter 8, the detector 9 beats, a voltage shaping unit 10 proportional to the steepness of the leading and trailing edges of the impulse noise, the amplifier 11 with an adjustable gain factor.

The rectangular pulse shaper 6 comprises a comparator 12, a second delay element 13, a first adder 14, a differentiating element 15, a two-half-period rectifier 16, a pulse expander 17, a pulse distributor 18.

Block 3 adjustable delay contains the second adder 19, the first 20 and the second 21 delay lines.

The device works as follows.

In the absence of impulse noise and in the presence of a signal and harmonic interference on the device, the latter pass through the passband of amplifier 4 and beat out on the pulse detector 5 as a beat, then pass through filter 8 having the necessary frequency response and passband. These oscillations are detected by the detector 9 and, in the form of a slowly varying voltage, regulate the threshold of the amplifier-limiter 7 so that, with an increase in the amplitude of the beat voltage, the threshold of the amplifier-limiter 7 and, consequently, the driver 6 increases, and when harmonic no disturbance is generated at the device input. In this case, the useful signal from the device input to its

the output through the element 1, the interrupter 2 passes without interruption and, therefore, is not distorted.

In the event of a pulse interference exceeding the value of the automatically set threshold on the limiting amplifier 7, the driver 6 generates an interrupting pulse expanded by an amount proportional to the control voltage supplied to its control input from the output of the amplifier 11.

The input of the amplifier 11 receives the voltage from the output of the detector 9. The control input of the amplifier 11 in this case receives the voltage from the output of the block 10. This block produces a voltage proportional to the rate of change of the leading and trailing edges of the impulse noise, i.e.

the voltage at the output of the block 10 is directly proportional to the steepness of the fronts of the impulse noise. This voltage determines the gain of amplifier 11. Note that block 10 produces a control for the leading and falling edges of the voltage of a pulsed disturbance of different polarity, but the gain of amplifier 11 is determined only by the absolute value of this voltage and does not depend on the sign .

Thus, the control input of the driver 6 from the output of the amplifier 11 receives a control signal that takes into account the magnitude of the amplifier-limiter 7,

taking place at a given time, and the steepness of the front and rear edges of impulse noise.

In accordance with the magnitude of this control signal, a pulse is generated at the output of the driver 6, the duration of which is equal to the duration of the pulse interference acting on the receiving path at any arbitrary point in time.

Let us consider in more detail the algorithm for forming the duration of the interrupting pulse at the output of block 3.

We will proceed from the condition that the blanking pulse interrupting the main path should be equal to the duration of the impulse noise. Then you can write (Fig. 4)

55

Gil Gif + Gbi + G3f,

(one)

where Type is the duration of the blanking pulse from the output of block 3;

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

Typhoid - the duration of the front edge of the impulse noise below the threshold level;

Gzf duration of the rear edge of the pulse noise below the threshold level.

A pulse of Gb duration is produced by comparator 12. Thus, the task is to determine the duration of Gif and G3f and lengthen the Gb duration for this value.

From FIG. 4a, it can be seen that .U, op. AUi.

Gif

tgen

tgar

(2)

 "°

gz

. "

where DC is the control voltage at the output of block 10 when measuring the steepness of the 1st front;

Tz delay time in block 10.

Then

y. t yUnop.

GIF G3H-Shch-,

GF GZH-sgE

or

Tif Gz XUnop X Kl; G3f TzHiporkh | 2

where

(four)

(five)

(6)

() (eight)

Since the duration m3 is a constant value, to determine

hyphae and T3f need to know the value of-.

This value can be determined using an amplifier 11 with a variable (adjustable) gain.

The Unop voltage must be supplied to one input of such an amplifier, and the DC voltage that controls the gain factor to another, then the output voltage of the amplifier 11 will be equal to

the value of -dgr te is Ki VAui, where KI is the gain factor of the amplifier 11.

UDOD

If you know the value of L g, you can determine the duration of g3f and typhoid by expanding

rhenium duration g3 l-y times, and

increasing the GBi duration by the values of hyphas and teffs, we obtain the duration of the interrupting pulse, equal to the duration of the impulse noise.

In the proposed device, a voltage is supplied from the detector 9 of the beats to the input of the amplifier 11, which controls the gain of the amplifier 11. The control input of the driver comes

the voltage from the output of amplifier 11, which determines the duration of the hyphae and r3f.

Consider the work of the imager 6 and block 3.

5Epura FIG. 4a depicts a single

impulse noise, and FIG. 46 is a blanking pulse generated by the path of detection of interfering pulses without taking into account the duration of the fronts of the disturbance. From 10 of these diagrams, the uncompensated remainder of the impulse noise is clearly visible.

When the threshold of the amplifier-limiter 7 is exceeded by impulse noise, the comparator 12 generates a rectangular pulse pulse with a duration of Tbi (Fig. 46), which through element 13 and the adder 14 enters the first output of the former 6 (Fig. 4c). Differentiated by the differentiating element 15 front and rear

20 the fronts of this pulse (Fig. 4d) are fed through the full-wave rectifier 16 to the input of the expander 17 (Fig. 4e). The expander 17 produces rectangular pulses (Fig. 4g), the duration of which

25 is determined by the magnitude of the output voltage from amplifier 11 (Fig. 4e) and is equal to the value defined by expression (4) and (5).

These pulses are fed to the input of the distributor 18, in which, in the initial state, the input is connected to the second output, the Impulse Hyph, corresponding to the leading edge of the pulse interference, goes to the second output of the distributor 18 and then to the second input of unit 3 (Fig. 4h). This impulse

35 sets the delay values: on the first line 20 Gif, on the second line 21 Ge. In addition, this pulse arrives at the first input of line 21 through the adder 19. The magnitude of rf is determined from the following considerations. Since it is desirable to perform delay element 1 in the form of a constant delay line (since it is analogous), the delay time is chosen to be 2 + Dg3, where Dgs is a constant 45 hold in element 13; TQ- is the maximum possible duration of the leading edge of the impulse noise actually acting in the channel.

Then, in order for the blanking impulse to coincide exactly in time with the moment when the interference passes through the interrupter 2, it is necessary that the delay in line 21 be set to T3 of the 2nd hyph (Fig. 4k).

When this condition is fulfilled, for any possible value of the leading edge duration of the hyphae, the delay in block 3 is always constant and equal to 2nd. Then the total delay in the imaging unit 6 and the block

50

55

3 is 2to + Dg3, which ensures the time normalization (Fig. 4k, m).

With the arrival of the hyphal pulse on the second passage of block 3, a Gby pulse is applied to its first input from the output of the adder 14 (Fig. 4i). The simultaneity of their arrival is ensured by the element 13. The GbI pulse is delayed by the Tif value in line 20, as a result of which it arrives at the first input of line 21 with the end of the hyphal pulse and is added to it in duration (fi-4k).

The impulse corresponding to the trailing edge G3f (Fig. 4g) enters the output of the expander 17, the first output of the distributor 18 (pos .; the pulse passing corresponding to the leading edge of the hyphal interference, the distributor 18 switches to the first output) and yes, Ie adds up in time adder 14 with gb

Thus, a single pulse passes through line 21, the duration of which is equal to the actual duration of the impulse noise: Gip Gif + Gbi + Gf. The indicated impulse at the output of unit 3 is delayed relative to the impulse noise at the device input by a constant value of 2nd + Dg3. Since this constant delay is taken into account in block 1, the interruption occurs only at the required time. The maximum delay time of line 21 is chosen to be 2nd, to allow the delay time to be recoded and the described algorithm to work with the minimum slope of the leading edge of the noise, i.e. when gif go Thus, the delay in line 21 consists of two parts: constant and variable

Gee. In this case, G3 can be adjusted from 0 to go.

The magnitude and delay in the line 20 hyphae can be adjusted from 0 to go. As mentioned, the adjustment of lines 20 and 21 by the voltage from the second input of unit 3 is carried out so that the condition: hyphae + G3 of the 2nd is fulfilled. Lines 20 and 21 can be made in the form of discrete delay lines with control units or in the form of controllable shift registers. The adder 19 is designed for isolating the circuits.

The signal at the output of block 3 is shown in FIG. 4l.

Thus, the device allows the blanking impulse to be framed, taking into account the duration of the leading and trailing edges of the impulse noise, which ensures

Claims (3)

1. An impulse noise protection device comprising a first delay element connected in series, the input of which is the device input and the chopper whose output is the device output connected in series 0 an amplifier-limiting device whose input is connected to the device input, a pulse detector, an amplifier-limiting device with an adjustable limitation threshold, and a variable-width pulse shaper connected in series to a beating filter, whose input is connected to the output of a pulsed detector, and a beating detector whose output connected to the control input of the amplifier 0 with adjustable gain and control input of the limiting amplifier with adjustable limiting threshold, the output of the amplifier with adjustable gain is connected to the control of the input of the former A variable-width rectangular pulse, characterized in that, in order to reduce the remainder of the pulsed disturbance with a leading leading edge, into it 0, an adjustable delay unit is introduced, the first and second inputs of which are connected to the first and second outputs of a variable-width square pulse shaper, respectively, and the output is connected to the control input of the chopper, and a voltage shaping unit proportional to the slope of the leading and trailing edges of the pulse interference, the input of which is connected to the output of the pulse detector, and the output is connected to the signal input of the amplifier with adjustable gain, 2. The device according to claim 1, characterized in that the former A variable pulse pulse contains a series-connected comparator, the input of which is the input of a variable pulse square wave former, the second element 0 delay and the first adder, the output of which is the first output of a variable-width square pulse generator, connected in series to a differentiating element, whose input is connected to the output of a comparator, a full-wave rectifier, a pulse expander, the control input of which is the control input of the driver variable pulse duration, and a pulse distributor whose first output is connected to another input of the first adder, and the second output is second in the output of a square pulse shaper of variable duration. 3. Device pop. 1, characterized in that the variable delay unit comprises a first delay line connected in series with an adjustable fiber. 2 20 2 Fig 3 The delay delay, the input of which is the first input of the adjustable delay unit, the second adder and the second delay line, the output of which is the output of the adjustable delay unit, the other input of the adder and the inputs of the adjustable signal of the first and second delay lines, is the second input of the adjustable delay unit. 27 i