RU1841332C - Device for forming narrow-band noise interference - Google Patents

Abstract

FIELD: radio interference.

SUBSTANCE: device relates to the field of radio interference and is intended for use in relay-type active interference stations. The claimed device contains a series-connected low-frequency normal noise generator and the first threshold block and a modulator amplifier and phase shifter. Additionally, a series-connected inverter, a second threshold unit, a negation unit and an adder are introduced into the device.

EFFECT: reduction in the power of the components of the interference spectrum at the carrier frequency of the re-emitted signal in a wide range of operating frequencies.

1 cl, 1 dwg

Description

The proposed device for the formation of narrow-band noise interference belongs to the field of radio countermeasures and is intended for use in active interference stations of the relay type.

Known devices for generating noise interference used to suppress the speed channel RJ with continuous and quasi-continuous radiation. Of the known devices, the closest in technical essence is the device for generating narrow-band noise interference, described in the "Explanatory note of the technical project "Geran-IVD". It contains a series-connected low-frequency normal noise generator, a threshold device and an amplifier-modulator, the output of which is connected to the control electrode electronic phase shifter The output of the phase shifter is the output of the prototype device.

Полученные импульсы усиливаются усилителем-модулятором и подаются на управляющий электрод электронного фазовращателя. В результате высокочастотный сигнал, поступающий на вход фазовращателя, манипулируется по фазе и преобразуется на выходе устройства в узкополосную шумовую помеху.The device works as follows. From the output of the generator, low-frequency normal noise enters the threshold device, where it is converted into pulses of random duration with an average duty cycle

The received pulses are amplified by the modulator amplifier and fed to the control electrode of the electronic phase shifter. As a result, the high-frequency signal at the input of the phase shifter is phase-shifted and converted at the output of the device into narrow-band noise interference.

A significant drawback of the prototype is a fairly strong dependence of the quality of the interference on the frequency of the input signal in the operating frequency range.

Let's explain this with an example.

The quality of noise interference of the relay type can be estimated by the ratio of the power of the components of the spectrum on the frequency carrier Р ₀ to the total interference power Р _∑ . For the prototype, the value of this ratio is determined by the expression (see B.D. Sergievsky, L.G. Oganesyants "Spectra of oscillations modulated in phase by fluctuations", Radio engineering and electronics, volume XI, issue 5, 1966)

- девиация фазы помехи.where

- interference phase deviation.

величина P₀ равна нулю.As can be seen from expression (I), with phase deviation

the value of P ₀ is equal to zero.

The phase deviation is determined by the amplitude of the modulating voltage and the steepness of the phase characteristic of the electronic phase shifter, which is used as a TWT. Since the slope of the TWT phase characteristic is linearly dependent on frequency (see E.M. Vereshchagin "Modulation in microwave generators", publishing house "Sov. Radio", 1972), then at a constant amplitude of the modulating voltage, the modulation index depending on on the frequency of the signal can be very different from its optimal value for a given frequency.

Modern electronic phase shifters have a fairly wide range of operating frequencies, for example: for TWT type UVF-4, the ratio of the operating frequency band to the average purity of the range is k = 0.4. If you choose the amplitude of the modulating voltage from the condition of obtaining the optimal phase modulation index at the middle frequency of the operating range, then at its edges (with a deviation of ± 20% from the average frequency), the quality of the interference will deteriorate significantly.

In particular, as follows from expression (I), for the prototype at the edges of the range, the value of the ratio:

The proposed device has as its main goal to reduce the dependence of the quality of relay-type noise interference on the frequency of the input signal in a wide range of operating frequencies.

The block diagram of the proposed device is shown in Fig.1.

The device contains:

- generator of low-frequency normal noise 1;

- threshold device 2;

- inverter 3;

- additional threshold device 4;

- negation scheme 5;

- adder 6;

- amplifier-modulator 7;

- electronic phase shifter 8.

The device works as follows. The signal from the noise generator 1 (Fig. 2a) directly, through the threshold device 2 and through the serially connected inverter 3 (Fig. 2b), the additional threshold device 4 and the negation circuit 5 is fed to the adder 6.

Threshold device 2 and additional threshold device 4 have a threshold equal to AND ₀ and operate so that the voltage at their outputs is equal to 2And ₀ as long as the input signal does not exceed the threshold level, and is zero when the signal exceeds the threshold level (Fig. .2c, d). The threshold value in both threshold devices is chosen equal to the rms value of the input process voltage

The output signal of the negation circuit 5 is illustrated by the diagram in FIG. 2e, and the output signal of the adder 6 by the diagram in Fig. 2e. As can be seen from the last diagram, the amplitude of the random process is within 2I ₀ .

From the output of the adder, a random signal is fed through the amplifier-modulator 7 to the control electrode of the electronic phase shifter 8. As a result, the high-frequency signal at the input of the phase shifter is modulated in phase by the generated random process and is converted at the output of the device into narrow-band noise interference.

The quality of noise interference generated by the proposed device is determined by the expression:

на средней частоте рабочего диапазона может быть определено по формуле:Nominal interference phase deviation

at the middle frequency of the operating range can be determined by the formula:

In particular, for k = 0.4 we obtain

что на 4,7 дБ лучше, чем в прототипе.With this choice of modulation index, the quality of the interference at the middle frequency of the range is -28.5 dB. At the edges of the frequency range in this case

which is 4.7 dB better than the prototype.

Thus, the proposed device provides a higher quality noise interference in a wide range of operating frequencies than the previously known device.

Claims (1)

A device for generating narrow-band noise interference, containing a low-frequency normal noise generator connected in series, and the first threshold unit, and a modulator amplifier, and a phase shifter, characterized in that, in order to reduce the power of the components of the interference spectrum, at the carrier frequency of the re-radiated signal in a wide range of operating frequencies an inverter, a second threshold unit, a negation unit and an adder are connected in series, while the second and third inputs of the adder are connected respectively to the outputs of the low-frequency normal noise generator and the first threshold unit, the output of the adder is connected to the input of the modulator amplifier, and the input of the inverter is connected to the output of the generator low frequency normal noise.

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