RU1841340C - The method of broadband electronic intelligence of signals of electronic means - Google Patents

Abstract

FIELD: electronic intelligence.

SUBSTANCE: invention relates to electronic intelligence signals in wide ranges of microwaves.

In the method of broadband radio intelligence of signals of electronic means, the frequency of the input signal is determined by generating a voltage depending on the frequency difference between the input and frequency-modulated reference signals. Next, determine the order of alternation of stress signs. If it corresponds to the reception of the signal on the mirror channel, the further passage of the signal is interrupted to indicate the time of reception on the mirror channel.

EFFECT: technical result is to increase the frequency resolution of the receiver.

1 cl, 2 dwg

Description

Radio-technical reconnaissance of signals in wide microwave bands is carried out mainly by superheterodyne receivers with broadband input devices, tunable in range using panoramic local oscillators.

Superheterodyne receivers provide high input sensitivity and high frequency resolution. The disadvantage of such receivers is that any signal is received twice: on the main and mirror channels. As a result, the number of signal marks at the output of the receiver is doubled. This leads to a parasitic loading of indicator-analyzing devices and a deterioration in the reconnaissance receiver's frequency resolution.

Known methods of suppressing spurious reception channels and separating signals received via the main and mirror channels. The distinguishing features of these methods is the introduction of additional modulation of the local oscillator frequency and conversion of the received signals in terms of spectrum, amplitude or duration. So, when implementing one of the methods, a shift and additional modulation of the panoramic local oscillator frequency is performed. The subsequent inverse frequency conversion of the signals eliminates the additional FM modulation of the useful signal and preserves it for spurious signals, which is used to isolate the signals received over the main channel.

Other well-known methods are also based on the use of additional modulation of the receiver's local oscillator in frequency and subsequent transformations of the signals in terms of spectrum, amplitude and duration.

The implementation of these methods of dealing with an increase in the number of signals due to repeated reception over the mirror (or combinational) channel is quite complicated. This mainly explains the fact that these methods have not yet been implemented in the receiving devices of electronic intelligence.

Below we propose an easier-to-implement method for protecting superheterodyne tunable receivers from signals received via an image channel. This method does not require any additional modulation by local oscillators of subsequent transformations of the received signals in terms of spectrum, amplitude and duration, as is done in opposed methods. It is easier to implement and differs significantly from known methods that are close in target characteristics.

The proposed method allows to reduce the load on the receiving and analyzing devices of the RTR receiver by half due to the exclusion of signals transmitted through the mirror channel, and thereby increase the reliability of the reconnaissance information provided by the receiver.

The essence of the method is illustrated by drawings.

Rice. 1. Typical characteristic of a frequency discriminator

U - voltage at the output of the discriminator;

Δω - receiver detuning frequency, equal to ω _g -ω _s ,

where ω _g - local oscillator frequency,

ω _with - the frequency of the reconnaissance signal.

- частоты гетеродина, отстоящие от частоты разведываемого сигнала ω_с на величину промежуточной частоты приемника;Rice. 2, a) Scheme of formation of the main and mirror reception channels;

- frequency of the local oscillator, separated from the frequency of the reconnaissance signal ω _with the value of the intermediate frequency of the receiver;

Δω _pr - intermediate frequency of the receiver;

b) typical discrimination characteristics for the mirror and main receiving channels.

The essence of the method consists in controlling the order of alternation of voltage signs at the output of the frequency discriminator and locking the input of the indicator-analyzing device for the time of receiving signals via the mirror channel.

It is known that the voltage at the output of the frequency discriminator is a sign-alternating function of the receiver detuning frequency (Fig. 1). In the absence of detuning (Δω=0), the voltage at the output of the frequency discriminator is zero. Changing the sign of the frequency detuning leads to a change in the sign of the output voltage.

In our case

at Δω < 0 the output voltage is negative,

for Δω > 0 - positive.

If the frequency tuning of the panoramic local oscillator occurs from the upper frequencies to the lower ones, then when the tuning area passes through the main channel (Fig. 2), the voltage at the output of the discriminator will first be positive and then negative.

At the moment the tuning band passes through the mirror channel, the alternation of voltage signs changes: first there will be a negative voltage, then a positive one.

Thus, the main receiving channel differs from the mirror channel in the alternation of voltage signs at the output of the frequency discriminator. This circumstance is supposed to be used in order to exclude signals received by the receiver via the image channel.

Depending on the accepted direction of tuning the frequency of the local oscillator, the alternation of the signs of the voltage of the frequency discriminator will be strictly defined both when receiving on the main and on the mirror channels. By determining the order of alternation of voltage signs, it is possible to distinguish the signal arriving via the mirror channel from the signal received via the main channel, and blocking the input of the indicator-analyzing device of the receiver for the duration of the signal reception via the mirror channel. For example, you can provide a character-determining device and configure it in such a way that it produces a control signal when receiving signals via the mirror channel. This control signal will make it possible to form a strobe signal for switching the input of indicator-analyzing devices in order to prevent the passage of the signal being scouted through the mirror channel. Thus, only the signals received by the main receiving channel will be processed in the indicator-analyzing devices. This will reduce the load on the receiving-analyzing devices and improve the frequency resolution of the RTR receiver.

Claims (1)

A method for broadband radio intelligence of signals of electronic means, based on determining the frequency of the input signal by generating a voltage depending on the frequency difference between the input and frequency-modulated reference signals, characterized in that, in order to increase the frequency resolution, the order of alternation of signs of the voltage is determined, and if it corresponds to the reception of the signal on the mirror channel, interrupt the further passage of the signal to indicate the time of reception on the mirror channel.

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