RU2583734C1 - Method of generating noise-immune radio signals - Google Patents

Abstract

FIELD: radio engineering and communications.

SUBSTANCE: invention can be used to increase noise immunity of radio signals in communication systems. Method of generating noise-resistant radio signal based on formation of a broadband signal, for which method comprises using extension of spectrum by forming a pseudo-random sequence, and is characterised by that modulation of gates of pseudorandom sequence using radio pulses, which is obtained by multiplying bi-orthogonal wavelet functions and signals with linear frequency modulation, in which modulation of logical element “1” and logic element “0” pseudorandom sequence set a different rate of increase in frequency at same time as bi-orthogonal wavelet functions using function of second derivative of Gaussian function.

EFFECT: high noise-immunity of radio signals in communication systems by increasing frequency bandwidth.

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Description

The invention relates to radio engineering and can be used to improve the noise immunity of radio signals (PC) in communication systems.

There are various methods of forming noise-resistant PC [RF patents No. 2231924, 2205496]. In these methods, pseudorandom sequence modulation (PSS) of the carrier wave is used to form noise-resistant noise-like PCs.

In the known method [patent RU 2231924, published on June 27, 2004], noise-resistant noise-like radio pulses (SRI) are formed to transmit binary information symbols with complex signals. The known invention relates to information transmission systems and includes minimal code-frequency modulation of the carrier frequency by summing the amplitude and phase modulated quadrature channels, modulating code sequences, which are obtained by transcoding the SRI code sequence, gating the resulting amount with a video pulse equal to the length of the code sequence, generating the opposite signal by inversion code of the modulating code sequence of one of the quadrature Anal.

The disadvantage of this method is the complexity of its implementation, associated with the need to form quadrature channels. In addition, the specified method employs an energetically non-optimal signal-code design, including amplitude-phase modulation, which reduces the effect of increasing noise immunity.

In the known method [patent RU 2205496, published May 27, 2003] a complex signal is generated and processed in noise-immune radio systems. The known invention relates to the field of radio engineering and includes phase manipulation of the carrier oscillation of the SRP and the information signal, on the receiving side, the removal of the SRP with subsequent demodulation in the Costas scheme, and a modified band noise is used as the carrier oscillation.

The disadvantage of this method is that increasing the stealth of the transmitted PC is achieved by reducing the noise immunity of the radio receiver.

The closest analogue in technical essence to the claimed is a method of generating noise-resistant signals [patent RU 2412551, published on 02.20.2011. Bull. No. 5]. In the prototype method, noise-resistant signals are generated based on the formation of a broadband signal, for which they use the expansion of the signal spectrum by the SRP method, which is modulated by binary phase shift keying. Moreover, biorthogonal wavelet functions (BVF) are used to modulate the PSP, while “0” and “1” are modulated by opposite BVF.

The disadvantage of the prototype is the relatively low noise immunity due to the insufficient increase in the width of the spectrum (occupied frequency band) of the PC modulated BCF.

The technical result of the claimed method is to increase the noise immunity of radio signals by increasing the width of the spectrum (occupied by them frequency band).

This is achieved by the fact that the method of generating noise-tolerant radio signals based on the formation of a broadband signal, which uses the expansion of the spectrum by the pseudo-random sequence method, which is modulated by biorthogonal wavelet functions, is characterized in that for the modulation of the logical elements of the pseudo-random sequence, radio pulses are used, which are obtained as a result of multiplication biorthogonal wavelet functions and signals with linear frequency modulation, for which l the logical element “1” and the logical element “0” of the pseudo-random sequence specify a different rate of increase in frequency, and the rate of increase in frequency in a signal with linear frequency modulation is set arbitrarily, but so that its value for modulation of the logical element “1” is not less than twice with respect to the logic element “0”, and as the biorthogonal wavelet functions, the functions of the second derivative of the Gaussian function are used.

Thanks to the new set of essential features in the present method, which consist of using radio pulses instead of the BVF, representing the result of multiplying the BVF and the LFM signals with different values of the rate of change of frequency, the spectrum width of the resulting PC is increased.

The claimed method is illustrated by drawings, which show:

FIG. 1 - numeric binary PSP 000100110101111, formed using a random number generator;

FIG. 2 is a temporary representation of the direct form of the BVF, representing the second derivative of the Gauss function;

FIG. 3 is a temporary representation of the inverse form of the BVF, representing the second derivative of the Gauss function;

FIG. 4 - temporary representation of the signal with the chirp for modulating the logical "1";

FIG. 5 is a temporal representation of the signal with the LFM for modulating the logical “0” (the rate of increase in the frequency of the signal with the LFM is doubled in relation to the rate of increase of the frequency used in the signal with the LFM intended for modulating the logical “1”);

FIG. 6 is a temporal representation of a radio pulse constructed on the basis of multiplication of the BVF, representing the second derivative of the Gaussian function, and a signal with an LFM for modulating the logical “1”;

FIG. 7 is a temporary representation of a radio pulse constructed on the basis of the multiplication of the BVF, representing the second derivative of the Gaussian function, and the signal with the LFM to modulate the logical "0";

FIG. 8 - PC element, formed by modulating the numerical binary SRP shown in Fig. 1, by radio pulses generated on the basis of multiplying the BVF and the LFM signals with different frequency increase rates to modulate the logical “1” and “0” SRP;

FIG. 9 is a PC element formed by modulating the numerical binary SRP shown in FIG. 1, by signals based on the direct form of the BVF for “1” and the inverse form of the BVF for “0”;

FIG. 10 is a modulus of the spectrum of a PC formed by modulating the numerical binary SRP shown in FIG. 1, by radio pulses formed on the basis of multiplication of BVF and signals with LFM with different speed of frequency increase for modulating logical “1” and “0” SRP;

FIG. 11 is a module of a PC spectrum formed by modulating the numerical binary SRP shown in FIG. 1 with signals based on the direct waveform of the BVF for “1” and the inverse form of the BVF for “0”.

The implementation of the claimed method is explained as follows.

1. Pre-set the numerical binary SRP.

A numerical binary SRP can be set, for example, using a random signal generator. Random signal generators are known and described, for example, in RF patent No. 2168260 dated 05/27/2001. The number of elements in the memory bandwidth should be at least two.

As an example in FIG. 1 shows a numerical binary PSP 000100110101111, formed using a random number generator.

2. Generate radio pulses as a result of multiplying the BVF and signals with the LFM to modulate the logical "1" and "0" of the SRP.

As the BVF, use the direct or reverse (inverse) form of the function (see Fig. 2 and Fig. 3), which represents the second derivative of the Gaussian function.

The function of the second derivative of the Gauss function is known. The principle of its formation is described, see N.M. Asafiev. Wavelet Analysis: Fundamentals of the Theory and Application Examples // Uspekhi Fizicheskikh Nauk, vol. 166, No. 11, 1996, p. 1152 and patent RU 2412551, published on 02.20.2011, Bull. No. 5.

LFM signals (see Figs. 4 and 5) are known and described, for example, see IS Gonorovsky. Radio circuits and signals. Textbook for high schools. Ed. 2nd, revised and supplemented. M .: "Soviet Radio", 1971, pp. 136-137.

When multiplying, select the BCF and the signals with the LFM so that the number of time samples for the BCF and the signals with the LFM is the same.

In this case, the multiplication procedure itself consists in sequentially multiplying the corresponding time samples of the BCF and the signals from the LFM.

In FIG. 6 shows a radio pulse generated as a result of multiplication of the BVF and the signal with the LFM to modulate the logical “1”. In FIG. 7 shows a radio pulse generated as a result of multiplying the BVF and the signal with the LFM to modulate a logical “0”.

In the formation of radio pulses, both direct and reverse (inverse) form of BVF can be used equally.

3. Modulate the PC element.

Modulation consists in the formation of a sequence of radio pulses in accordance with the logical elements of the SRP. Instead of logic elements “1” and “0”, substitute the corresponding radio pulses with different frequencies of increasing frequency. The modulation process of the SRP is known, see patent RU 2412551 C2, published on 02.20.2011. Bull. No. 5.

For the example of FIG. 8 shows a PC element modulated by a sequence of radio pulses in accordance with the SRP shown in FIG. one.

When modulating a PC element, it doesn’t matter which of the radio pulses designed to modulate logical “0” or “1” has a higher frequency increase rate. An important point is the difference in the values of the rate of increase in frequency in the signals with the LFM.

The use of generated radio pulses to modulate the logical elements of the memory bandwidth leads to an increase in the occupied bandwidth of the PC, i.e. to expand the spectrum.

As an example in FIG. 9 shows a PC element formed in accordance with the SRP value (see FIG. 1) according to the prototype method.

In FIG. 10 shows a spectrum formed on the basis of the proposed method (for the PC element in FIG. 8), and in FIG. 11 is a spectrum formed on the basis of the prototype method (for the PC element in Fig. 9).

Analysis of the obtained spectra showed an increase in the occupied bandwidth for the PC formed according to the claimed method (see Fig. 10 and Fig. 11). Moreover, the greater the difference in the rate of increase in the frequency of signals with LFM, the greater the expansion of the spectrum of the resulting PC.

Thus, thanks to a new set of essential features, the claimed method provides an increase in the width of the spectrum for the formed PC due to the use of radio pulses with different rates of increasing frequency for modulating elements of the PSP sequence.

Claims (1)

A method for generating noise-tolerant radio signals based on the formation of a broadband signal, for which use is made of a pseudorandom sequence spread spectrum modulated with biorthogonal wavelet functions, characterized in that radio pulses are used to modulate the logical elements of the pseudorandom sequence, which are obtained by multiplying biorthogonal wavelet functions and signals with linear frequency modulation, for which the modulation of the logical element "1 and logical element “0” of the pseudo-random sequence specify a different rate of increase in frequency, and the rate of increase in frequency in a signal with linear frequency modulation is set arbitrarily, but so that its value for modulation of logic element “1” differs no less than twice to the logic element “0”, and as the biorthogonal wavelet functions, use the functions of the second derivative of the Gauss function.

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