RU2421876C1 - Generation method of chaotic super-high-frequency pulses - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: non-linear passive element having inverse dynamic characteristic, frequency-selective element and variable attenuators are introduced to feedback circuit of self-oscillator of chaotic SHF signals; self-oscillator is tuned to generation mode of chaotic SHF signal with power level which is higher than threshold level of non-linear passive element; frequency bandwidth of frequency-selective element is chosen so that suppression level of spectrum components of signal of low power level relative spectrum components of high power level is constant within the whole bandwidth, and following period of chaotic SHF pulses is controlled by the change of attenuation value of attenuators. ^ EFFECT: generation of periodic sequence of chaotic SHF pulses with controlled value of their following period. ^ 7 dwg

Description

The invention relates to radio engineering and information transfer and can be used in communication communication systems for transmitting information messages based on the use of chaotic microwave (microwave) signals.

There is a method of generating electromagnetic noise vibrations, based on the use in the circuit of the noise generator of a linear and nonlinear amplifiers covered by a feedback circuit, which are traveling-wave lamps and named so conditionally in accordance with the mode in which they worked: the linear amplifier is in almost linear mode amplification, non-linear amplifier - in a substantially non-linear mode on the falling section of the amplitude characteristic, i.e. on a plot with negative slope. The presence of a falling section on the amplitude characteristic of a nonlinear amplifier leads to the fact that the generator turns into a noise generator in which there are no additional external sources of noise signal, and the mode of generation of electromagnetic noise vibrations is carried out due to the self-dynamics of the self-oscillating system (see A.C. No. 1125735, IPC Н03В 29/00).

There is another method for generating broadband microwave chaotic signals, in which the signal is sequentially amplified by at least two amplifier stages, the first of which operates in low gain mode, and the second in nonlinear signal amplification mode, limit the signal after amplification in the third amplifier stage, which operates in the limiting mode, a part of the signal branches off after the limitation to the load, and the remaining part of the signals is fed to the first of the amplification stages. The generator contains the first and second amplification stages, the restriction stage, made in the form of a third amplification stage, and a microstrip coupler (see RF patent No. 2327278, IPC Н03В 29/00).

The disadvantage of the above methods is the absence in the considered devices of the mode of generation of chaotic microwave pulses.

There is also known a method for generating high-power chaotic radio pulses for direct chaotic communication systems, including introducing an external microwave radio pulse into the feedback circuit of a microwave klystron oscillator with delayed feedback, the oscillator is tuned to maximum chaotic power in an autonomous mode, an external microwave radio pulse is selected at low power, and its amplitude is selected and frequency until a sharp drop in chaotic power during the duration of the radio pulse (see patent for the invention of the Russian Federation No. 2349027, IPC H 03K 3/84).

The disadvantage of this method is the introduction of an external microwave pulse to generate chaotic microwave pulses.

The task of the invention is to autonomously (without an external signal) generate a periodic sequence of chaotic microwave pulses with a controlled value of the pulse repetition period.

The technical result consists in suppressing instantaneous values of the power of a chaotic microwave signal, the level of which is below the threshold of a nonlinear device with an inverse dynamic characteristic, in letting this device pass only the peak values of the power of a chaotic microwave signal, whose level is above the threshold, in the frequency filtering of the spectral components of the chaotic microwave -signal (self-modulation frequencies) by a frequency-selective device, which leads to their passive synchronization and to the generation of chaotic microwave pulses c, as well as in controlling the repetition period of chaotic microwave pulses by changing the signal power in the feedback circuit of the oscillator.

The problem is solved in that in a method for generating chaotic microwave pulses, which includes introducing a nonlinear passive element with an inverse dynamic characteristic, a frequency-selective element and variable attenuators into the feedback circuit of a chaotic microwave signal, according to the solution, the oscillator is tuned to a chaotic microwave signal generation mode with a power level above the threshold level of a nonlinear passive element, width at baseband frequency-selective element is selected so that the level of suppression of the spectral components of relatively small power level of the spectral components of a large signal power level was constant during the entire band, and change the amount of attenuation of attenuators controlled repetition period of chaotic microwave pulses.

The method can be implemented on the basis of an annular chaos oscillator and a nonlinear element with inverse dynamic characteristic having a different design. As a chaos generator in the microwave range, ring oscillators based on both vacuum and solid-state power amplifiers can be used in which the microwave signal is randomized either due to the nonlinearity of the active element or due to the nonlinearity of the passive element. As a nonlinear element with an inverse dynamic characteristic in the microwave range, a nonlinear magnetostatic wave transmission line or a system based on it can be used in the literature as “signal-to-noise ratio amplifier” or “noise suppressor” (see US Patent No. 4283692, IPC) Н01Р 1/23; AS USSR No. 1434515, IPC Н01Р 1/23; utility model patent of the Russian Federation No. 41550, IPC Н01Р 1/23; US patent No. 5307516, IPC Н04В 001/26; patent for the invention of the Russian Federation No. 2281587 IPC Н01Р 1/23). A feature of a nonlinear element with an inverse dynamic characteristic is the suppression of the spectral components of a chaotic signal whose power level is below the threshold of the onset of the nonlinear operation of the element, and the transmission of spectral components of a chaotic signal whose power level is above the threshold (Sharaevsky Yu.P., Grishin BC, Gurzo V. V., Derunov A.V., Shakhat A.A. Interaction of Regular and Noise Signals in a Nonlinear Transmission Line on Magnetostatic Waves // Radio Engineering and Electronics. 1995. V. 40, No. 7. S.1064-1068).

The proposed method is illustrated by drawings, in which Fig. 1 shows a block diagram of an annular chaos oscillator with a noise suppressor on the MCB, and Fig. 2 shows the dependences of the output power ( _Pout ) on the input power ( _Pinch ) of the nonlinear delay line on the MCB and the squelch on the MCB , figure 3 - noise suppressors on the MSV of various types: a) "microstrip transmission line - ferromagnetic film"; b) "resonant transmission line is a ferromagnetic film"; figure 4 - spectrograms and temporal implementation of chaotic microwave signals at the output of an autonomous chaos generator based on transistor (solid-state) power amplifiers with noise suppressor on PMSV type "microstrip transmission line - ferromagnetic film", figure 5 - spectrograms and temporal implementation of chaotic Microwave pulses at the output of a stand-alone chaos generator based on klystron (vacuum) power amplifiers with noise suppressor on PMSV type "microstrip transmission line - ferromagnetic film", Fig.6 - spectrograms time realizations of random microwave pulses at the output of the autonomous chaos generator based transistor (solid state) of power amplifiers with noise reduction on backward volume MSW (BVMSW) type "resonant transmission line - ferromagnetic film."

The positions in the drawings indicate:

1, 6 - microwave power amplifiers;

2 - frequency selective element;

3 - directional coupler;

4, 7 - variable attenuators;

5 - nonlinear delay line on the MSW;

8 - noise suppressor on the MSV;

9 - dynamic characteristic of a nonlinear delay line on the MSW;

10 - dynamic characteristic of the noise canceler on the MSV;

11 - a metal screen;

12 - polycrust substrate;

13 - ferrite film;

14 - microstrip;

15, 16 - input and output microstrip communication elements of the resonator with the path;

17 - microstrip resonator.

The essence of the method lies in the fact that an additional nonlinear element with an inverse dynamic characteristic 10 is introduced into the feedback circuit of the ring microwave oscillator operating in the autonomous generation of chaotic microwave signal 10. Selecting the gain of the ring microwave oscillator so that the power level of the generated chaotic microwave signal was above the threshold level of a nonlinear passive element with inverse dynamic characteristic 10, we suppress instantaneous values powerfully ti chaotic microwave signal whose level is below the threshold of the nonlinear device, and select only the peak power value of the chaotic microwave signal whose level is above the threshold. This leads to the generation of chaotic microwave pulses in the time domain. At the same time, we select the frequency bandwidth of the frequency-selective element 2 such that a certain number of spectral components corresponding to the self-modulation frequencies of the chaotic microwave signal, for which the “large signal / small signal” ratio is constant in this frequency band, are allocated in the frequency domain. In this case, the nonlinear phase shift corresponding to the peak values of the power of the chaotic microwave signal is almost the same for each of the selected peak values. In the frequency domain, this leads to the establishment of a constant phase shift between the spectral components of the signal, the frequency interval between which is the reciprocal of the pulse repetition period. The occurrence in the time domain of microwave pulses and the frequency of their repetition is the result of the combined action of the inverse dynamic characteristics of the nonlinear passive element 10 and the frequency filtering of the frequency-selective element 2, leading to passive phase synchronization of the spectral components of the chaotic microwave signal. The value of the self-modulation frequencies depends on the power level of the chaotic microwave signal, therefore, a change in the attenuation in the feedback circuit using attenuators 4, 7 leads to a change in the power level of the chaotic microwave signal and, as a consequence, to a change in the repetition period of chaotic microwave pulses. The control period of the sequence of chaotic microwave pulses can be carried out within certain limits of the change in the power level of the chaotic microwave signal corresponding to the boundaries of the phase synchronization region of its spectral components (self-modulation frequencies).

The method was implemented using the device depicted in figure 1.

The device comprises serially connected microwave power amplifier 1, frequency selective device 2, directional coupler 3, variable attenuator 4, non-linear delay line to the MCB 5, microwave power amplifier 6, variable attenuator 7 and a noise canceler on the MCB 8 connected to the input of the microwave amplifier power 1.

To demonstrate the generation of a periodic sequence of chaotic microwave pulses, a ring microwave oscillator was chosen as the chaos generator, in the feedback circuit of which a nonlinear delay line was used on MSW 9. The chaotic dynamics of this oscillator is due to stochastic self-modulation by thermal spin waves of a magnetostatic wave excited at the signal frequency generation (Demidov V.E., Kovshikov N.G. Mechanism of the emergence and stochastization of self-modulation of intense spin waves. // ZhTF. 1999 T. 69, No. 8. S.100-103). This mechanism of signal randomization is associated with the parametric excitation of the thermal spin waves by the magnetostatic wave (first-order parametric processes) and with the inverse effect of the latter on the MSW. In this case, the chaotization of the microwave signal can be observed with a delay line both on the surface MSW and on the bulk MSW (Grishin S.V., Grishin VS, Hramov A.E., Sharaevsky Yu.P. Generation of a broadband chaotic signal in a self-oscillating system with nonlinear transmission line on magnetostatic waves. // ZhTF. 2008. T. 78, No. 5. P.89-98). For the ferrite films most commonly used in practice with saturation magnetization of ~ 1760 G, first-order parametric processes are observed in the frequency range up to 4.9 GHz - in the case of excitation of MSSW, up to 3.2 GHz - in the case of excitation of OMSW, and when metallization is one of the sides films in the frequency range up to 9.8 GHz in the case of PMSV excitation (see A.V. Vashkovsky, BCStalmakhov, Yu.P. Sharaevsky "Magnetostatic waves in microwave electronics. Publishing house of Saratov University, 1993). In the ring oscillator, both transistor and klystron power amplifiers operating in the low-signal mode and serving mainly to compensate for the loss of the microwave signal in the feedback circuit were used as microwave amplifiers of power 1, 6 in the ring oscillator. In this case, the parameters of both amplifiers were chosen so that the operating frequency band of the amplifiers was in the frequency range of the existence of first-order parametric processes of the MSW in the ferrite film 13 and coincided with the frequency band of the frequency-selective element 2 of the oscillator, and the saturation power level of each of the microwave amplifiers 1 , 6 was higher than the threshold of occurrence of the nonlinear section on the dynamic characteristics of the delay line 9 and the noise canceler on the MCB 10.

Two types of noise suppressors were chosen as MSW 8 noise suppressors: 1) a microstrip transmission line - ferromagnetic film type noise suppressor containing a shielded substrate 11, 12 with a microstrip applied to it 14, on top of which a ferrite film 13 was applied, in which for a certain orientation and the magnitude of the external constant magnetic field is excited by PMSV (figa); 2) a noise suppressor of the type “resonant transmission line - ferromagnetic film”, containing a ferrite film 13 and a microstrip line — a dielectric substrate shielded on one side 11, 12 with a microstrip deposited on its opposite side. The microstrip is made with two breaks along its length and forms a resonant system consisting of a microstrip half-wave resonator 17 and two microstrip communication elements (input 15 and output 16), while the ferrite film 13 is located along the transverse axis of symmetry of the microstrip resonator 17. At a certain orientation and the magnitude of the external constant magnetic field in the ferrite film 13 is excited OOMSV (figb). In both cases, the noise canceling parameters on the MSW 8 (the value of the external constant magnetic field, the resonant frequency of the microstrip resonator, etc.) are selected so that the first-order parametric processes of the MSW are allowed, the working frequency band of the noise canceling 8 coincides with the frequency band of the frequency-selective element 2 oscillator and the level of suppression of the spectral components of the signal of a small power level relative to the spectral components of a large power level was constant in the entire band.

As a frequency-selective element 2, passive or active filtering elements of a solid-state or vacuum nature were used.

Figures 4a and b show spectrograms and temporal realizations of chaotic microwave pulses generated by a self-oscillator with solid-state power amplifiers based on GaAs field-effect transistors with a Schottky barrier, with a frequency-selective element based on a volume microwave resonator and with a noise suppressor based on a microstrip “microstrip” type the transmission line is a ferromagnetic film. " By changing the attenuation on the attenuators, the repetition period of the chaotic microwave pulses was controlled (Fig. 4a, b). So, in Fig. 4a, the period of succession of chaotic microwave pulses was T> 50 μs, and in Fig. 4b, as a result of a decrease in the attenuation in the ring, T = 10.4 μs. Fig. 4c shows the results demonstrating the absence of generating a periodic sequence of chaotic microwave pulses in the absence of a noise suppressor on the MSW in the microwave feedback oscillator circuit. In this case, a broadband chaotic microwave signal is generated, however, in the time domain, a periodic sequence of chaotic microwave pulses is not observed.

Figure 5 shows spectrograms and temporal realizations of chaotic microwave pulses generated by a self-oscillator with vacuum power amplifiers based on five-cavity span klystrons, which are simultaneously frequency-selective elements, and a noise canceler of a similar type. From the presented results it follows that the use of vacuum nature power amplifiers as active elements does not lead to the disappearance of the effect of autonomous generation of chaotic microwave pulses, the repetition period of which could also be controlled using variable attenuators.

Figure 6 shows spectrograms and temporal realizations of chaotic microwave pulses generated by a self-oscillator with solid state power amplifiers based on GaAs field-effect transistors with a Schottky barrier, with a frequency-selective element based on a volumetric microwave resonator and with a noise suppressor on OOMSV type "resonant transmission line - ferromagnetic film. " This noise suppressor on OOMSV operates in the lower frequency range, where, however, first-order parametric processes of OOMSV are allowed. From the presented results it follows that the use of a noise suppressor on an MSW of a different type in the feedback microwave oscillator chaos oscillator does not lead to the disappearance of the autonomous generation of chaotic microwave pulses, the repetition period of which could also be controlled using variable attenuators.

Claims (1)

A method for generating chaotic microwave pulses, comprising introducing a non-linear passive element with a reverse dynamic response, a frequency-selective element and variable attenuators into the feedback loop of a chaotic microwave signal from a self-oscillator, characterized in that the oscillator is tuned to generate a chaotic microwave signal with a power level above a threshold level of non-linear passive element, frequency bandwidth frequency-selector of the element is chosen so that the level of suppression of the spectral components of the signal of a small power level relative to the spectral components of a large power level is constant throughout the band, and the period of chaotic microwave pulses is controlled by changing the attenuation attenuation.

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