The method of suppressing narrowband interference in a broadband system

 

The invention relates to radio engineering. The technical result is to increase the coefficient of suppression of narrowband interference. The invention consists in that in the transmitting tract form a broadband noise signal in the frequency band (F0, F1), modulate the broadband noise signal according to a given modulation, pass the received signal through the distribution environment, take it imposed on him a narrow-band interference filter in the frequency band (F0, F1), generate two signals, one of which is a result of amplification of the filtered signal and limiting its amplitude, as well as a second signal using the aforementioned filtered signal or linearly amplified without changing the shape of the filtered signal, Peremohy received two signals, the resulting signal is filtered in the frequency band [Fut(F1-F0), distinguish the envelope of the received signal and demodulator to receive the information signal, whereut- frequency band of the spectrum change of the square of the amplitude of the voltage noise. 6 Il.

The invention relates to electrical engineering and can be used in communications technology, such as the broadband is delirous the amplitude of the signal, phase, frequency, or both. In all these systems the main type of interference are narrowband interference, i.e. interference, in which all the energy is concentrated in a narrow band of frequencies. Therefore, the task of filtering the complex signal with a simultaneous impact on the receiver fluctuation noise and powerful narrowband interference in the spectrum of the useful signal, is very topical. This is due to the fact that powerful narrowband station can completely disrupt communication in broadband systems, as in the multiplier correlator narrowband interference is converted into fotoemulsii signal having a linear spectrum with envelope proportional to sin(x)/x, and if powerful enough interference noise at the output of the correlator can exceed the collapsed level of the useful signal.

There are many ways to eliminate this phenomenon, for example quasi-optimal linear filtering, the rejection of part of the spectrum, compensation methods, and so on (1).

A disadvantage of known methods is their complexity.

The closest to this invention is a method of suppressing narrowband interference in a broadband system, wherein in the transmitting tract form provided by pressinformation, form a digital phase noise signal with a center frequency F0logically summed with previously obtained digital pseudo-random signal, amplify the received signal in the receiving device, accept the transmitted signal overlaid in the distribution environment narrowband signal with frequency Fut&;&;FSRPfilter the received signal by passing through the high-frequency band-pass filter with a bandwidth of 2 FSRPand the Central frequency F0transform the input signal into a voltage proportional to the power received signal is filtered in the frequency band (Fut-FSRP), increase, limit the received signal, and then the correlation method of processing the receive signal to the mismatch between the clock frequency FSRPthe transmitted signal and the corresponding clock frequency of the receiving device (2).

The disadvantage of this method is the low coefficient of suppression of interference from powerful narrowband stations.

The technical result of the present invention is to increase the ratio of suppression of the bellows or group of narrowband interference in a limited frequency band, including frequency modulation and scanning interference that will improve the quality of communication at the expense of increasing the noise immunity of the useful signal.

This technical result is achieved in that in the method of suppressing narrowband interference in a broadband system in the transmitting tract form a broadband noise signal in the frequency band (F0F1), modulate the broadband noise signal according to a given modulation to modulate power with modulation frequency Fmod&;&;(F1-F0), pass the received signal through the distribution environment, take it in the receiving device overlaid with the distribution environment narrowband interference filter in the frequency band (F0F1), generate two signals, one of which receives the gain filtered in the frequency band (F0F1signal limiting its amplitude, as well as a second signal using the aforementioned filtered signal or linearly amplified without changing the shape of the filtered signal, Peremohy received two signals, the resulting signal is signal and scientists demodulator to receive the information signal, whereFut- frequency band of the spectrum change of the square of the voltage amplitude narrowband interference.

In Fig.1 presents a block diagram of a device implementing the method of suppressing narrowband interference in a broadband system;

in Fig.2 is a block diagram of the propagation medium;

in Fig.3 - form filtered in the frequency band (F0F1the signal obtained after amplification and restriction;

in Fig.4 - shape filtered in the frequency band (F0F1) signal or linearly amplified filtered in the frequency band (F0F1signal; and

in Fig.5 spectrum of the resulting signal obtained after multiplication of these two signals;

in Fig.6 - range filtered in the frequency band [Fut, ((F1-F0)] the resulting signal.

A device that implements the method of suppressing narrowband interference in a broadband system contains the transmit path, which includes connected in series generator 1 broadband noise signal, the modulator 2 and the transmitting antenna 3 (Fig.1), the signal from which is through the distribution environment (Fig.2) is fed to the receiving antenna 3’ prinimaya , F1), the output of which is connected to the input of the amplifier 6. The output of the amplifier 6 is connected to the input of the linear amplifier 7 and the amplifier 8 with the constraint that the outputs are connected to the inputs of block multiplication 9 connected to the output to the input of bandpass filter 10 bandwidth [Fut, (F1-F0)]. From the output of bandpass filter 10, the signal is supplied to the input unit 11 allocation of the envelope of the signal filtered in the frequency band [Fut(F1-F0)]. The received signal at the demodulator 12 to highlight the information signal.

The considered method of suppressing narrowband interference in a broadband system is as follows.

In the transmitting tract of the generator 1 form a broadband noise signal in the frequency band (F0F1), which modulate power (modulator 2) according to a given modulation with a modulation frequency Fmod&;&;(F1-F0). The received signal is transmitted in the distribution environment, such as radio waves (Fig.2), where it is superimposed narrowband interference. Usado-modulated, frequency-modulated, scanning and so on, but must satisfy the following conditions: frequency narrowband interference Futsatises F0<F<Fand the frequency band of the spectrum change of the square of the amplitude of the voltage noise (Futmust be much less than the frequency band of the spectrum change of the square of the voltage amplitude modulated broadband noise signal at the point of reception. Thus, the input of the receiving device receives the signal, equal to the vector sum of the voltages of the useful signaland narrowband interferenceThis mixed signal is fed to the input of bandpass filter 5 with a bandwidth of frequencies (F0F1). Then the filtered signal is pre-amplified by the amplifier 6, is divided into two signals. The first receive signal after amplification filtered in a specified frequency band signal and limiting its amplitude in the amplifier 8. When a signal with interference through the amplifier-limiter interference suppress the useful signal and its output signal is formed of the normalized values ofIn the linear amplifier 7. Linear amplifier 7 does not alter the shape of the filtered signal and it will beThe form of these two signals is shown in Fig.3, 4, respectively. Received two signals received at the respective inputs of block multiplication that multiplies them, providing output the resulting signal, whose spectrum is shown in Fig.5. Then the resulting signal is filtered bandpass filter 10 bandwidth [Fut(F1-F0)]. When narrowband interference is a local oscillator for the useful signal and in the condition in which the frequency band of the spectrumFutmuch less than the frequency band of the spectrum change of the square of the voltage amplitude modulated broadband noise signal, after transmission of the resulting signal multiplication through the band-pass filter with a bandwidth of frequencies [Fut(F1-F0)] is excluded itself narrowband interference Fig.6. Highlighting the next envelope of the filtered signal, the received useful signal, modulated power, which is further processed by known laws of tvline in a variety of ways, for example, using the amplitude-frequency modulation or pulse modulation using any of the methods of coding and pseudo-random sequences.

Thus, the information is then stored in the power change signal and transmitted across the frequency band (F0F1), and when the transfer range during processing in the receiver is moved together with the spectrum.

From this it follows that the limiting factor for this method of suppressing narrowband interference is a band of the spectrum of changes in the power of interference, and not the frequency band occupied by the disturbance in the air that can suppress and even scanning a hindrance, not knowing the real location it in the air.

Sources of information

1. Address, control and communications systems. /Edited TUZOVA, I. M.: Radio and communication, 1993, S. 256-259, 261-264.

2. EN 2127021 C1 (KALUGIN centuries and others), 27.02.1999.

Claims

The method of suppressing narrowband interference in a broadband system, wherein in the transmitting tract form a broadband noise signal in the frequency band (F0F1), modulate the broadband noise signal according to a given modulation to modulate power frequency seize him in the receiving device overlaid with the distribution environment narrowband interference, filtered in the frequency band (F0F1), generate two signals, one of which receives the gain filtered in the frequency band (F0F1signal limiting its amplitude, as well as a second signal using the aforementioned filtered signal or linearly amplified without changing the shape of the filtered signal, Peremohy received two signals, the resulting signal is filtered in the frequency band [Fut, (F1-F0) allocate envelope of the received signal and demodulator to receive the information signal, whereFut- frequency band of the spectrum change of the square of the amplitude of the voltage noise.

 

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