RU2319167C1 - Device for adaptive management of spectral dissipation characteristics of a radiolocation object - Google Patents

Abstract

FIELD: radio engineering, possible use for reducing radiolocation noticeability of an object.

SUBSTANCE: device includes control block, knowledge base, onboard radio reconnaissance station and multi-channel generator of control signals, N controllable nonlinear radiolocation deflectors, connected in a certain manner. In adaptation mode, device ensures minimum of intensities of spectral components of dissipated field at irradiation frequencies by causing influences in controllable nonlinear radiolocation deflectors, which are formed by multi-channel generator of control signals, parameters of which are determined by control block on basis of information contained in knowledge base, which is accumulated during training mode. As control signal for controllable nonlinear radiolocation deflectors, a signal may be used which represents an additive mixture of constant shift voltage and monochromatic oscillation with frequency, which exceeds supposed pass band of radiolocation station receiver of the opponent, or a signal, which causes appearance of new spectral components in receiver band, disruption of response modulation rule of matched filter in radiolocation station of the opponent and results in substantial reduction of signal to noise ratio at its output.

EFFECT: improved quality of radio-counteraction to radiolocation stations of the opponent by means of semi-active adaptive management of spectral dissipation characteristics of the object being protected.

3 cl, 14 dwg, 1 tbl

Description

The present invention relates to the field of radio engineering and can be used to reduce the radar visibility of the object.

Known device "Custom absorber" (US patent No. US 3309704, 1967), used for radar masking of objects and includes a controlled coating, which is a quarter-wave absorber, tuned to the frequency of exposure by changing the electric thickness of the coating over time, as well as means for determining object irradiation frequencies, temperature sensor, feedback circuit, computer and memory bank containing exposure parameters that control the coating.

Signs of an analogue that coincide with the essential features of the claimed device are means for determining the frequency of exposure (in the inventive device, an on-board radio intelligence station) and a memory bank (in the inventive device, a knowledge base).

The reason that prevents the technical result from being obtained is the use of a custom quarter-wave absorber that does not allow controlling the spectral characteristics of the electromagnetic (EM) field scattered by the masked object.

It is also known device "Broadband passive simulator of a moving target (US patent No. US 6559790, 2003), used for electrical simulation of objects by generating Doppler frequencies, consisting of a corner reflector, closed by chains of pin diodes. Each chain has its own fixed switching frequency.

A sign of an analogue that coincides with the essential features of the claimed device is a radar reflector that transforms the spectrum of the scattered field.

The reasons that impede the achievement of the technical result are the low efficiency of frequency conversion, the inability to control the spectral characteristics of the reflected field and the lack of adaptation of the device to changing irradiation conditions.

Of the known solutions, the closest in technical essence to the claimed invention is “A device designed to reduce the level of the reflected electromagnetic field” described in patent No. GB 2322260, MKI G01S 7/36 7/38, 1984. The device contains a monopulse receiver of radio pulses of the enemy radar, which determines the angles of the object; means for changing the amplitude and phase of the received radio pulses (controlled phase shifter, controlled attenuator) and means for re-emitting these radio pulses in the direction of the enemy radar (circulator, amplifier, antenna). The specified device also includes a knowledge base containing information about the necessary changes in the amplitude and phase of the radio pulses.

The operation of the device consists in changing the amplitude and phase of the received radio pulses in such a way that the EM field created during their reradiation compensates for the field reflected from the object in the direction of the radar. That is, the amplitude of the field reradiated by the prototype device is equal to the amplitude of the field scattered by the object, and the phase is shifted by π. For each irradiation angle, the values of the amplitudes and phases of the re-emitted radio pulses are given a priori mathematical expression or are determined experimentally by the criterion of the minimum of the scattered field when the object of its own radar is irradiated and stored in the knowledge base.

Signs of the prototype, coinciding with the essential features of the claimed device, are a monopulse receiver (in the claimed device is an on-board radio intelligence station) and a knowledge base.

The reasons that impede the achievement of a technical result are as follows: the device is complex, has large dimensions and weight, which is undesirable for an aircraft; to work in the entire range of irradiation angles, one device is not enough, it is necessary to use several similar devices installed on the “shiny points” (BT) of the object; re-emission of the probe signal unmasks the object in directions different from the direction on the enemy radar; the use of a transmit-receive antenna, circulator, attenuator, phase shifter and amplifier limits the range of working frequencies of the prototype; the impossibility of controlling the spectral characteristics of the reflected field.

The task to which the proposed technical solution is directed is to improve the quality of the enemy’s radar countermeasures by means of semi-active adaptive control of the scattering spectral characteristics of the protected object.

The technical result is achieved by the fact that in the device for adaptive control of the spectral characteristics of the scattering of a radar object containing an onboard radio intelligence station, a knowledge base having two operating modes: a training mode and an adaptation mode, a control unit connected to the knowledge base is introduced, the input of which is connected to the onboard output a radio intelligence station, a multi-channel control signal generator, the input of which is connected to the control unit, and the outputs to controlled non-linear radar reflectors; providing in the adaptation mode a minimum of intensities of the spectral components of the scattered field at the irradiation frequencies by applying to the controlled non-linear radar reflectors the effects generated by the multichannel generator of control signals, the parameters of which are determined by the control unit on the basis of the knowledge in the knowledge base, accumulated in the training mode, using as the control signal for controlled non-linear radar reflectors signal, which is an addi an active mixture of a constant bias voltage and a monochromatic oscillation with a frequency exceeding the width of the estimated bandwidth of the enemy radar receiver, or a signal of a special shape, which leads to the appearance of new spectral components in the receiver band and, when using complex sounding signals with a large base, the response modulation law is destroyed matched enemy radar filter and a significant reduction in the signal-to-noise ratio at its output.

The invention is illustrated by the following figures:

Figure 1 - Block diagram of a device for adaptive control of the spectral characteristics of the scattering of a radar object. The composition of the claimed device includes:

1 _i - i-th controlled non-linear radar reflector (UNRO),

2 - multi-channel control signal generator,

3 - control unit,

4 - knowledge base,

5 - airborne intelligence station.

Figure 2 - Device adaptive control of the spectral characteristics of the scattering of a radar object in the adaptation mode, where 6 _j - j-th radar of the enemy.

Figure 3 - Device adaptive control of the spectral characteristics of the scattering of a radar object in training mode and a system for measuring radar characteristics. The figure 3 introduced the notation:

7 - radar landfill,

8 is a block measuring the radar object and control the radar of the landfill,

9 - RLH knowledge base.

Figure 4 - Layout device adaptive control of the spectral characteristics of the scattering of a radar object and a system for measuring radar characteristics:

10 - radar measuring stand anechoic chamber (BEC),

11 - interface unit

12 - personal computer (PC),

13 - knowledge base,

14 - management program,

15 - spectrum analyzer program,

16 - analog-to-digital Converter (ADC),

17 is a program generator control signals,

18 - digital-to-analog converter (DAC).

Figure 5 - Design layout UNRO.

Figure 6 - Turning on the diode in the layout of the UNRO.

Figure 7 - Current-voltage characteristic of the diode GA501D.

Figure 8 - The dependence of the signal level proportional to the power density of the scattered field at the irradiation frequency ω ₁₀ on the bias voltage (at ω ₁₀ = 2π · 2.8, 2π · 3.0 and 2π · 3.2 GHz).

Figure 9 - Dependence of signal levels proportional to the power densities of the spectral components of the scattered field at frequencies ω ₁₀ , ω ₁₂ and ω ₁₃ on the bias voltage (at ω ₁₀ = 2π · 2.8 GHz).

Figure 10 - Dependence of the relative power densities of the spectral components of the scattered field at frequencies ω ₁₁ , ω ₁₂ and ω ₁₃ on the bias voltage (at ω ₁₀ = 2π · 2.8 GHz).

Figure 11 - Detective level signals proportional to the power density of the spectral components of the scattered field on ₁₁ frequencies ω, ω ₁₂ and ω ₁₃ of the bias voltage (at ω = 2π · ₁₀ 3 GHz).

Figure 12 - Dependences of the relative power densities of the spectral components of the scattered field at frequencies ω ₁₁ , ω ₁₂ and ω ₁₃ on the bias voltage (at ω ₁₀ = 2π · 3.0 GHz).

Figure 13 - Dependence of signal levels proportional to the power densities of the spectral components of the scattered field at frequencies ω ₁₁ , ω ₁₂ and ω ₁₃ on the bias voltage (at ω ₁₀ = 2π · 3.2 GHz).

Figure 14 - Dependence of the relative power densities of the spectral components of the scattered field at frequencies ω ₁₁ , ω ₁₂ and ω ₁₃ on the bias voltage (at ω ₁₀ = 2π · 3.2 GHz).

и азимутальных углов

. Конструкция УНРО 1_i, выбирается из соображений максимально эффективного переноса энергии падающего поля с основной на комбинационные частоты, диапазона рабочих частот и геометрии БТ, на которой он расположен. Таким образом, диапазон рабочих частот системы определяется только конструкцией УНРО 1_i и может быть достаточно большим.The operation of the proposed device is illustrated by the following description. Controlled non-linear radar reflectors (the design of which is based on non-linear elements - for example, semiconductor diodes) 1 _i are installed on the body of the protected object and close the BT. Each UNRO 1 _i operates in a specific sector of elevation angles

and azimuthal angles

. The design of the UNRO 1 _i is selected for reasons of the most efficient transfer of the energy of the incident field from the fundamental to the combination frequencies, the operating frequency range, and the BT geometry on which it is located. Thus, the operating frequency range of the system is determined only by the design of the UNRO 1 _i and can be quite large.

The device has two operating modes: adaptation mode and training mode. In the adaptation mode, the on-board intelligence station 5 transmits to the control unit 3 data on the angular coordinates θ _j , φ _{j of the} jth radar of the enemy 6 _j relative to the protected object and data on the instantaneous frequency of the irradiation field ω _j (data on the current exposure conditions). For each UNRO 1 _i , in the range of working angles of which the direction falls on the enemy radar 6 _j (i.e. θ _1i ≤θ _j ≤θ _2i and φ _1i ≤φ _j ≤φ _2i ), control unit 3 selects from knowledge base 4 control action parameters corresponding to current irradiation conditions and providing a minimum of the reflected signal at the incident field frequency. They are transmitted to a multi-channel control signal generator 2, to the outputs of which UNRO 1 _{i are} connected. As a control signal, for example, an additive mixture of a constant bias voltage U _СМ and a monochromatic oscillation with a frequency Ω greater than the estimated bandwidth of the enemy radar receiver 6 _j can be used. Under the influence of the control signal on the nonlinear elements of the UNRO, the spectrum of the scattered field is transformed and part of its power is transferred to frequencies ω _mn = mω ± n Ω (where m, n = 0, ± 1, ± 2 ...) that are outside the passband enemy radar receiver.

Also, control can be carried out by signals of a special shape, which leads to the appearance of new spectral components in the receiver band and, when using complex sounding signals with a large base, the destruction of the modulation law of the response of the matched enemy radar filter and a significant decrease in the signal-to-noise ratio at its output.

The training mode of the device is used to fill the knowledge base 4 in the process of field tests. In this case, the inventive device is connected to a system for measuring radar characteristics, which includes a radar of the landfill 7, a unit for measuring the radar facility of the object and control of the radar of the landfill 8, the knowledge base of the radar 9 (Fig.3).

The radar measurement unit of the object and the radar control of landfill 8 intercepts the control of the adaptive control device of the spectral characteristics of the scattering of the radar object. He sets the control unit 3 parameters of the control signals for UNRO 1, generates commands to change the conditions of the irradiation of the object for the landfill radar 7, and also receives information about the current values of the measured characteristics of the scattering of the object and enters them into the knowledge base of the radar 9.

At the end of RLH of the measurement process, an analysis and processing of data from the knowledge base RLH 9, the parameters of control signals are determined for each UNRO 1 _i, corresponding to each possible exposure condition and to ensure a minimum of the reflected signal. These parameters are entered into the knowledge base 4 and the learning process is completed.

The possibility of achieving a technical result is confirmed by the fact that the authors developed and tested a model of an adaptive control device for the spectral characteristics of the scattering of a radar object and a system for measuring the radar characteristics of a protected object (Fig. 4), which includes a BEC 10 radar measuring stand with continuous unmodulated radiation at a frequency ω , non-linear reflector 1, interface unit 11, PC 12. The PC is a hardware-software complex containing ADC 16 and CA P 18. The software of the complex includes the knowledge base 13, the control program 14, the spectrum analyzer program 15 and the control signal generator program 17. The control program 14, by means of the interface unit 11, sequentially establishes a number of angles θ, φ and radiation frequencies ω of UNRO 1 within the given limits [θ _min ; θ _max ], [φ _min ; φ _max ] and [ω _min ; ω _max ], respectively. For each irradiation condition, the control program 14, through the control signal generator program 17, sequentially generates a series of control actions, which are an additive mixture of bias voltage U _СМ and low-amplitude low-frequency monochromatic oscillation with frequency Ω supplied to DAC 18. From the output of DAC 18, the control voltage through the interface unit 11 is supplied to the UNRO 1. The UNRO dissipates the oscillation with a frequency ω and emits non-linear conversion products at frequencies ω _mn = mω ± n Ω. Frequencies only close to ω fall into the passband of the receiving part of the BEC 10 radar measuring stand. From its output, a signal containing information about the level and spectral composition of the scattered UNRO electromagnetic field with spectral components of frequency nω is supplied through the interface unit 11 to the input of the ADC 16. The complex software 14, 15 analyzes the spectrum of the digitized signal and enters 13 parameters into the knowledge base control action, irradiation conditions and the corresponding levels of spectral components of the received signal.

As used in the layout UNRO 1 is designed to operate at wavelengths of 10 cm and is a corner reflector, one face of which there is a folded dipole length λ _10/4 (Figure 5). In the place of attachment to the face in the section of the vibrator included a semiconductor switching diode GA501D (Fig.6). The spectral composition of the field scattered by the UNRO is controlled by applying to the diode a monochromatic signal with a frequency of 1 kHz and an amplitude of 50 mV with an offset that can be changed in the range of ± 0.8 V.

The results of the layout for the irradiation frequencies of 2.8 GHz, 3.0 GHz and 3.2 GHz are shown in Fig.8-14 and table 1.

Table 1 Irradiation frequency ω ₁₀ , GHz 2.8 3.0 3.2 Change in power density fields at a frequency of ω ₁₀ , dB 4.0 4.6 13.5 The maximum power density level of the spectral components of the field at the sum and difference frequencies about the level of the spectral components at a frequency ω _{of 10} dB second order ω ₁₁ -17 -15.5 -12.5 third order ω ₁₂ -26 -28 -21 fourth order ω ₁₃ -32 -33 -27

The change in the power density level of the scattered field at the irradiation frequency ω ₁₀ is from 4 dB (at a frequency of 2.8 GHz) to 13.5 dB (at a frequency of 3.2 GHz). The maximum level of power density of the spectral components of the field at second-order combination frequencies is -12.5 dB relative to the level of spectral components at the fundamental frequency; third order - -21 dB, fourth - -27 dB. The minimum level of power density of the spectral components of the field at combination frequencies is limited by the level of intrinsic noise of the layout.

Claims (3)

1. A device for adaptive control of the spectral characteristics of the scattering of a radar object, containing an onboard radio reconnaissance station, a knowledge base of control signal parameters, which has two operating modes - a training mode and an adaptation mode, characterized in that a control unit is introduced into it for selecting parameters from the knowledge base control actions corresponding to the current conditions of irradiation of the object and providing a minimum of the reflected signal from the object, and connected to the specified knowledge base, for which it is connected to the output of the airborne reconnaissance station, a multichannel control signal generator, the input of which is connected to the specified control unit, and the outputs to controlled non-linear radar reflectors, with the possibility of ensuring in the adaptation mode the minimum intensities of the spectral components of the reflected signal at the frequencies of the irradiation of the radar object by applying to guided nonlinear radar reflectors of impacts generated by a multichannel generator controlling the signal in which parameters for each managed nonlinear radar reflector analyzed and determined on the basis of being in knowledge base information collected in the learning mode, during ground tests and measuring the performance given by the radar unit. 2. The device according to claim 1, characterized in that as a control signal for controlled non-linear radar reflectors, a signal is used, which is an additive mixture of a constant bias voltage and a monochromatic oscillation with a frequency greater than the expected bandwidth of the receiver of the enemy radar station (radar) of the enemy. 3. The device according to claim 1, characterized in that as a control signal for controlled non-linear radar reflectors, a signal is generated with the possibility of providing new spectral components of the reflected signal in the band of the enemy radar receiver, breaking the modulation law of the response of the matched filter of the enemy radar receiver and reducing the ratio signal to noise output.

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