RU2776663C1 - Method for simulation of echoes of moving target in detection zone of tested radar station - Google Patents

Abstract

FIELD: radiolocation.

SUBSTANCE: invention relates to radiolocation; it can be used for the simplification, reduction in time and costs of testing of a radar station placed on a real position on the detection, accompaniment and recognition of targets, as well as on noise immunity. A method for simulation of echoes of a moving target in a detection zone of a tested radar station additionally consists in that signals converted on an intermediate frequency (hereinafter – IF) are subjected to agreed filtration in N filters, signals isolated at their outputs are detected, compared to a threshold, a type of a probing signal is determined, a signal is formed on IF with a modulation corresponding to a pulse characteristic of a maximum signal filter, a formed signal is converted on a carrying frequency of the tested radar station, divided into two components, which are shifted by phase on π/2, their amplitudes are adjusted for providing their emission with polarization corresponding to an echo of the simulated target, and supplied to corresponding inputs of a two-input receiving and transmitting antenna of a simulator, and emitted.

EFFECT: obtaining a possibility of simulation of echoes and interference emitted from an unmanned aerial vehicle (UAV) and corresponding to real energy, spectrum, correlation, polarization and trajectory parameters of aerodynamic, ballistic targets or jamming stops performing a flight in a detection zone of a tested radar station.

1 cl, 2 tbl, 14 dwg

Description

1. Technical field to which the invention belongs

The invention relates to radar and can be used to simplify, reduce the time and cost of testing a radar located at a real position for detection, tracking and recognition of targets, as well as for noise immunity.

2. State of the art

A known method of testing the radar [Leonov A.I., Leonov S.A., Nagulinko F.V. Radar testing. Performance evaluation. - M.: Radio and communications. 1990, p. 3, p. 25], including the creation of a full-scale signal-interference radar environment using targets and jammers launched along specified trajectories, detection, capture and tracking of targets, statistical processing of the measured parameters of target trajectories.

The disadvantage of this method is a significant amount of hardware required for testing, and hence its high cost. This is explained by the fact that the testing of such a complex device as a radar station is associated with a number of expensive organizational and technical measures, including the provision of flights of targets (aircraft, helicopters, missiles and other objects of various classes and purposes) in the radar field of view along specified trajectories, the involvement of special directors interference, equipment for recording measurements and evaluating test results.

A simulation and test complex for a radar station is known [RF Patent RU No. 2533779C2, publ. overflight, on board which is installed a flight navigation system connected to a satellite navigation system and a measuring radio-electronic device associated with a control point. The target for creating a natural environment in the field of view according to a given flight program is made in the form of an unmanned aerial vehicle (UAV) with a wing, empennage, fuselage, an engine and a landing device, equipped with a launcher, on the guide of which a pusher is installed and on the side of the engine propeller a retractable retractable starter. A stop is fixed on the fuselage in its lower part along the longitudinal axis, which contacts the end surface of the pusher during takeoff, and the landing device is installed in the compartment, on the wall of which an opening flap connected to an automatic lock is fixed.

The disadvantage of this simulation and test complex for a radar station is the limitation on the range and speed of the simulated target, which are due to the capabilities of the UAV.

A known system for checking and testing air defense means [RF Patent RU No. 109870 U1, publ. 10/27/2011, System for checking and testing air defense means, IPC G01S 7/40], containing an air target with a control device, a radar detection station and a target acquisition and tracking station, a device for recording parameters for detecting and tracking a target, and the air target is completed in the form of a UAV with a variable effective dispersion area (ESR).

The disadvantage of the known device is the limitation on the range and speed of the simulated target, which are due to the capabilities of the UAV.

Known simulator of a moving target [US Patent No. 6067041, publ. 05/23/2000, Moving target simulator, MPK G01S 7/40], containing a radio receiver, a digital memory that provides the required delay of the received radio signal, an amplitude modulator, a Doppler modulator, a frequency synthesizer, mixers, amplifiers, a controller for controlling the process of delay and modulation of the simulated signal and a control personal computer. The essence of using a known device for testing the radar is as follows. A moving target simulator is placed close to the radar under test and receives the signals emitted by it. The received signals are converted to an intermediate frequency, delayed by a time corresponding to the range to the simulated target, modulated in amplitude in accordance with the range to the target and its RCS, modulated in Doppler frequency in accordance with the speed of the simulated target, converted to the carrier frequency of the radar and radiated to her side.

The disadvantage of the known device is the impossibility of simulating the angular displacements of the target, and hence the impossibility to evaluate the entire field of view of the tested radar, as well as the impossibility of simulating the polarization properties of the simulated echo signals.

The closest in technical essence and the achieved result to the proposed method is the method chosen as a prototype for simulating the radar signal of the target of a monopulse radar station [RF Patent RU 2391682 C1, publ. 06/10/2010, Method for simulating the radar signal of the target of a monopulse radar station, IPC G01S 7/40 (2006.01)]. The method consists in the fact that the simulator receives signals emitted by the tested radar, converts them to an intermediate frequency, modulates them in accordance with the speed of the simulated target, its range and EPR, transfers their spectrum to the carrier frequency of the tested radar and radiates them in its direction with two antennas located on an arc of a circle with a center coinciding with the antenna of the tested radar. The ratio of the powers radiated by a pair of spatially separated antennas determines the current angular position of the target.

The disadvantage of this simulation method is the limited angular sector of the radar signal simulation, the complexity of its use when testing a radar located at a real position, and the impossibility of simulating the polarization properties of simulated echo signals corresponding to the characteristics of real moving targets.

3. Disclosure of the invention

The objective of the invention, to which the claimed invention is directed, is the development of a new method for generating the required (given) signal-interference environment by emitting simulated echo signals or interference from the UAV, corresponding in their energy, spectral, correlation, polarization and trajectory parameters to the echo signals of real moving targets or signals of jammers in the interests of testing the radar, which ensures the achievement of the following technical result: obtaining the possibility of simulating echo signals or interference emitted from UAVs and corresponding to real energy, spectral, correlation, polarization and trajectory parameters of moving aerodynamic or ballistic targets, or jammers flying in the zone detection of a tested radar located at a real position, and thereby reducing the time and cost of testing it in terms of assessing the capabilities for detection, tracking and recognition of real moving targets, as well as noise immunity.

The problem is solved, and the required technical result when using the invention is achieved by the fact that in the method of simulating the echo signals of a moving target, which consists in the fact that the simulator receives probing microwave signals of the tested radar, limit their amplitude with an attenuator, amplify in a high frequency amplifier ( UHF), are converted to an intermediate frequency (IF), the signals additionally converted to IF are subjected to matched filtering in N filters, where the impulse response of a certain filter corresponds to a certain modulation variant of the probing microwave signal of the radar under test, the signals extracted at the filter outputs are detected, they are compared with a threshold, determine the type of probing microwave signal of the tested radar, choosing the maximum of the signals that exceeded the threshold, form a signal on the IF with modulation corresponding to the impulse response of the filter in which the maximum signal was selected, with a delay relative to the probing signal of the radar under test, corresponding to the distance between the simulator and the simulated moving target, with a carrier frequency shift by the Doppler shift value determined by the radial velocity of the simulated target, and with amplitude modulation corresponding to the range to the simulated target, its RCS and random fluctuations characteristic of this type of simulated target , convert the generated signal to the carrier frequency of the tested radar, separate the generated microwave signal into two components, phase-shift one component of the microwave signal by an angle π/2, adjust the amplitude of each component so as to ensure the radiation of the microwave signal with a given polarization, apply one component to the first input-output, and the other component - to the second input-output of the two-input receiving-transmitting antenna, oriented in the direction of the tested radar, and radiate with polarization corresponding to the polarization of the echo signal of the simulated target, and the simulator is placed on a UAV equipped with a flight navigation system th, ensuring its flight in the far zone of the tested radar antenna with movements during the flight in the azimuth-elevation plane, similar to the movements of the simulated target, and in range and speed - with the range and speed of the flight of the simulated target reduced by a factor of K, where the value of K is selected based on the capabilities of the UAV in terms of height and speed of its flight.

Comparative analysis with the prototype shows that the proposed method has other significant new distinctive features from the prototype. The new distinguishing features of the proposed method are:

- placement of a target echo simulator on a UAV flying in the far zone of the antenna of the tested radar, with movements during the flight in the azimuth-elevation plane, similar to the movements of the simulated target, and in range and speed - with the range and speed of flight reduced by K times a simulated target, where the value of K is selected based on the capabilities of the UAV in terms of height and speed of its flight;

- determination of the type of probing microwave signal of the tested radar;

- radiation by the simulator of simulated echo signals with a polarization corresponding to the polarization of the probing signal of the tested radar and the reflective properties of the simulated target.

Distinctive features are essential, since each of them is necessary, and all together they are sufficient to achieve the task, the solution of which is directed by the claimed invention.

4. Explanations for graphic materials

In FIG. 1 shows a diagram of a device for implementing the method, where the following designations are accepted:

1 - two-input receiving-transmitting antenna (PTA); 2 - the first antenna switch (AP); 3 - second AP; 4 - input phase shifter (PV); 5 - adder; 6 - attenuator; 7 - high frequency input amplifier (UHF); 8 - inlet mixer; 9 - input intermediate frequency amplifier (IFA); 10 - demodulation block; 11 - digital signal processor (DSP); 12 - the first local oscillator; 13 - second local oscillator; 14 - device for controlling and recording flight parameters (CU and RPP); 15 - signal shaper (FS); 16 - modulation block; 17 - outlet mixer; 18 - divider; 19 - output PV; 20 - the first output UHF; 21 - second output UHF; 22 - the first controlled attenuator; 23 - second controlled attenuator; 24 - flight and navigation system (PNS); 25 - ground control device (CU); 26 - gyro-stabilized platform (GSP); 27 - UAV; 28 - tested radar.

In this case, the input-output 1 of the PPA 1, which is located on the GSP 26, is connected to the input-output 1 of the first AP 2, the input 2 of which is connected to the output of the first controlled attenuator 22, and the output 3 is connected to the input 2 of the adder 5, input-output 2 PPA 1 is connected to the input-output 1 of the second AP 3, the input 2 of which is connected to the output of the second controlled attenuator 23, and the output 3 is connected to the input of the input phase shifter 4, the output of which is connected to the input 1 of the adder 5, the output of which is connected to the input of the attenuator 6, the output of which is connected to the input of the input UHF 7, the output of which is connected to the input 1 of the input mixer 8, the input 2 of which is connected to the output 1 of the first local oscillator 12, and the output is connected to the input of the booster 9, the output of which is connected to the input 1 of the demodulation unit 10, input 2 which is connected to the output of the second local oscillator 13, and the outputs 1 and 2 are connected respectively to the inputs 1 and 2 of the DSP 11, the output of which is connected to the input 1 of the CU and RPP 14, the input 2 of which is connected to the output of the PNS 24, and the output 1 is connected to the input 1 P the first controlled attenuator 22, the output 2 is the input 1 of the second controlled attenuator 23, and the output 3 is the input of the FS 15, the outputs 1 and 2 of which are connected respectively to the inputs 1 and 2 of the modulation block 16, the output of which is connected to the input 1 of the output mixer 17 , the input 2 of which is connected to the output 2 of the first local oscillator 12, and the output is connected to the input of the divider 18, the output 1 of which is connected to the input of the first output UHF 20, and the output 2 is connected to the input of the output phase shifter 19, the output of which is connected to the input of the second output UHF 21 , the output of which is connected to the input 2 of the second controlled attenuator 23, the output of which is connected to the input 2 of the second AP 3, the connection of the PNS 24 with the ground control unit 25, as well as the connection of the PPA 1 with the radar 28 is carried out over the air. When this device 1-24 and 26 are placed on the UAV 27.

In FIG. 2 explains the calculation of the elevation angle of the simulated ADC and the UAV 27, as well as the flight altitude of the UAV 27 using the cosine theorem.

In FIG. Figure 3 shows the result of calculating the elevation angle of the simulated ADC trajectory depending on the distance to it at the height of the phase center of the antenna of the tested radar 28. H _z =10 m and the flight of the simulated ADC at a height of H _max =10000 m.

In FIG. 4 shows the result of calculating the trajectories of the UAV 27 in the "range-altitude" plane, used to estimate the scaling factor K from below.

In FIG. 5 explains the relation of the coordinates X _T , Y _T , Z _T of the topocentric rectangular coordinate system (CS) with the coordinates D, Az, B of the spherical CS. Topocentric rectangular SC is a rectangular SC with the beginning in the phase center of the antenna of the tested radar 28, where the 0Y _T axis is directed to the zenith along the local normal to the Earth's surface, the 0X _T and 0Z _T axes lie in the plane of the local horizon and together with the 0Y _T axis form the right SC, moreover, the axis 0Z _T lies in the plane of the normal to the antenna web/electrical axis of the antenna. Here A ₃ is the azimuth of the OZ _T axis, which is measured in the plane of the local horizon from the north direction in a clockwise direction.

ось

которой проходит через меридиан точки стояния РЛС 28. При пересчете сначала координаты из топоцентрической прямоугольной СК пересчитываются в геоцентрическую СК

а затем производится доворот осей

и

до осей

геоцентрической СК Х_Г, Y_г, Z_Г. Эти геоцентрические СК жестко связаны с Землей и вращается вместе с ней. Здесь же показаны геодезические координаты РЛС 28 - долгота

и широта

In FIG. 6 explains the relationship of the coordinates X _G , Y _g , Z _G of the geocentric SK with the topocentric rectangular SK. Geocentric SC is a rectangular SC with the origin in the center of the Earth, where the OZ _Г axis is directed along the Earth's rotation axis to the north, the OX _Г axis lies in the equatorial plane and passes through the zero meridian, the OY _Г axis lies in the equatorial plane and complements the SC to the right one. Here is the geocentric SC

axis

which passes through the meridian of the radar station 28. When recalculating, first the coordinates from the topocentric rectangular CS are recalculated into the geocentric CS

and then the axles are rotated

and

to axes

geocentric SK Х _Г , Y _г , Z _Г . These geocentric SCs are rigidly connected to the Earth and rotate with it. It also shows the geodetic coordinates of the radar 28 - longitude

and latitude

In FIG. 7 explains the connection of the geodetic CS with the planar coordinates of Gauss-Kruger (one of the six-degree zones is shown).

In FIG. 8-13 illustrate the results of modeling errors in the positioning of the UAV 27 for a spherical SC.

In FIG. 14 explains the calculation of the emission delay time of the simulated signal.

To implement the proposed technical solution, standard equipment can be used.

PPA 1 can be made in the form of a turnstile antenna [I.N. Grigorov. Antennas. M.: Radiosoft, 2003, p. 152, fig. 13.1].

The first AP 2 and the second AP 3 can be made in the form of low power strip circulators, for example, FPTSN2-15 [Low power circulators [Electronic resource]: URL: https://www.domen.ru/files/upload.pdf ].

Phase shifters 4 and 19 can be made in the form of pieces of coaxial cable of appropriate length.

Adder 5 and divider 18 can be made as two-way adders/dividers of the QPD2-30-3000-1-S type [2-Way Power Dividers/Combiners [Electronic resource]: URL: https://www.qualwave.com/products /2-way-power-dividers-combiners.htm].

The attenuator 6 can be made in the form of a manual attenuator type 5-3-127-A-1-S-12V [Belov L.A. Attenuators of microwave signals // Electronics: NTB. 2006, No. 2].

UHF 7, 20 and 21 can be implemented as low noise UHF type ADCA3270 [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

Mixers 8 and 17 can be made in the form of a low-noise double balance mixer type LTC5510 [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

IF 9 can be made in the form of an amplifier type ADL5541 [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

The demodulation unit 10 can be made in the form of a quadrature demodulator with an AD6676 chip type ADC [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

The DSP 11 may be implemented as a high performance mixed signal digital signal processor of the ADSP-21991 type [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

Local oscillators 12 and 13 can be made in the form of microwave generators type HMC586LC4B [Analog Devices. [Electronic resource]: URL: https://www.ana-log.com].

UU and RPP 14 can be made in the form of a microcomputer type LP-174 [LP-174 User's manual. Edition 1.3, 2016. [Electronic resource]: URL: https://www.manualslib.com/download/1449575/Commell-Lp-174.htm].

FS 15 can be made in the form of a vector signal generator capable of generating signals of a given amplitude, shape and phase structure, at a given frequency and with the required time delay, such as Agilent E4438C [Control and measurement solutions Agilent. USA: Agilent catalogue, 2014].

The modulation unit 16 can be made in the form of a digital quadrature modulator with an interpolator (at the input) and a digital-to-analog converter (at the output) of the AD9856 chip type [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

Controlled attenuators 22 and 23 can be made in the form of attenuators with digital control type HMS1119 [Analog Devices. [Electronic resource]: URL: https://www.analog.com].

PNS 24 with ground control unit 25 can be made in the form of a flight and navigation system of a transport aircraft [RF Patent RU 2597814 C1, Flight and navigation system of a transport aircraft, IPC G01C 23/00 (2006.01), 2016].

GSP 26 can be made in the form of a gyro-stabilized suspension of the required load capacity [Site-portal https://russiandrone.ru. [Electronic resource]: URL: https://russiandrone.ru/catalog/poleznaya-nagruzka/girostabilizirovannye-podvesy/girostabilizirovannye-platformy].

UAV 27 can be made in the form of a UAV [RF Patent RU 2666493, Unmanned aerial vehicle, MCP V64S 39/00, 2018].

Radar 28 can be made in the form of a radar type P-18R [Military-technical training. Air Force RTV radar device. P-18R radar station: textbook. at 2 o'clock 4.1 / E.N. Garin, D.D. Dmitriev, V.N. Tyapkin and others; ed. E.N. Garin. - Krasnoyarsk: Sib. feder. un-t, 2012].

5. Implementation of the invention

The method for simulating echo signals of a moving target is implemented as follows. The trajectory of an aerodynamic or ballistic target is preselected (calculated), the echo signal of which will be simulated for testing the radar. it and UAV 27. In the memory of the DSP 11, the complex values of the impulse responses of digital filters are entered, which are copies of signals at an intermediate frequency planned for use in the tested radar 28. These impulse responses are used when executing the digital filtering algorithm implemented in the DSP 11 to determine the type of probing the signal emitted by the tested radar 28 during the next probing of space. The following data is entered into the memory of the CU and RPP 14:

- characteristics of N 28 probing signals planned for use in the radar (duration, operating frequency, phase and frequency modulation);

- characteristics of the simulated target along the entire trajectory of its flight, namely: range, EPR, Doppler frequency addition, amplitude-time modulation determined by the echo signal fluctuation model, and echo signal polarization.

The selection of the coordinates of the points of the trajectory of the simulated target is carried out in a spherical SC (see Fig. 5), where:

;the distance D of the phase center of the radar antenna 28 to the point of the trajectory of the simulated target is determined by the length of the radius vector

;

на плоскость местного горизонта;azimuth Az - is the angle measured from the OZ _T axis to the projection of the radius vector

to the plane of the local horizon;

и его проекцией на плоскость местного горизонта.elevation angle B - is the angle between the radius vector

and its projection onto the plane of the local horizon.

The trajectory of the movement of the UAV 27 must completely repeat the trajectory of the simulated target in azimuth and elevation. The range and speed of movement of the UAV 27 must be reduced by a factor of K compared to the range and speed of the simulated target. The value of the coefficient is selected from the conditions of the flight of the UAV 27 in the far zone of the radar antenna 28, as well as from its capabilities in terms of altitude and flight speed.

After that, the coordinates of the points of the trajectory of the movement of the UAV 27 must be recalculated into the geodesic SC, where ϕ - latitude, λ - longitude, H - height. The coordinates of the points of the simulated trajectory of the UAV 27 and the corresponding times of passage of these points, as well as the speed of its movement, are entered into the flight task, which is entered into the memory of the PNS 24.

After turning on the tested radar 28, the UAV 27, using the ground control unit 25, is displayed at the starting point of the simulated trajectory and starts moving in accordance with the flight task stored in the memory of the PNS 24. In this case, the PPA 1 during the flight is oriented with the help of the GPS 26 to the tested radar 28.

When the UAV 27 is irradiated with a probing signal of the microwave tested radar 28, the PPA 1 receives this signal in two polarizations and transmits it through the input-output 1 of the first AP 2 to the input 2 of the adder 5, and through the input-output 1 of the second AP 3 and the input FV 4 to the input 1 of the adder 5, from the output of which the resulting signal is fed to the input of the attenuator 6. The attenuated microwave signal from the output of the attenuator 6 is fed to the input of the input UHF 7. After amplification, the received microwave signal is fed to the input 1 of the input mixer 8, to the input 2 of which a heterodyne signal with output 1 of the first local oscillator 12. From the output of the input mixer 8 and after amplification in the IF 9, the signal converted to an intermediate frequency is fed to the input 1 of the demodulator 10, to the input 2 of which the signals of the second local oscillator 13 are received. quadrature components and analog-to-digital conversion. The digitized signal in two quadratures from the outputs 1 and 2 of the demodulator 10 is fed to the corresponding inputs of the DSP 11. The DSP 11 is convolving the input digital signal with the impulse responses of N digital filters. The number of digital filters implemented in the DSP 11, and, accordingly, the number of calculated convolutions corresponds to the possible number of used radar 28 probing signals. The maximum value of the convolution will be observed when the impulse response used for its calculation will correspond to the probing signal used by the radar 28 at the current stage of detection/tracking/recognition of the target. To exclude false detection of the probing microwave signal of the tested radar 28, the convolution module with the maximum value is compared with the threshold. The type of probing microwave signal of the tested radar 28 is determined by the modulus of the convolution, which has a maximum value and exceeded the threshold, and is encoded with a digital code, which is fed from the output of the DSP 11 to the input 1 of the CU and RPP 14. The CU and RPP 14, receiving information from the PNS 24, fixes the time and coordinates of the UAV 27 at the time of receiving the probing microwave signal of the tested radar 28, and also calculates the delay time of the simulated signal emission depending on the distance between the tested radar 28 and the UAV 27, its amplitude modulation in accordance with the RCS of the simulated target, with the distance to it and its radar portrait, Doppler frequency addition, polarization. By the time the simulated signal is emitted, the CU and RPP 14 from output 3 transmits information about the parameters of this signal to FS 15, and from outputs 1 and 2, respectively, to control inputs 1 of the first and second controlled attenuators 22 and 23 - attenuation codes. FS 15 generates the required simulated signal in digital form in quadratures and outputs it to the modulator 16, which generates the simulated signal in analog form at an intermediate frequency, and transmits it to the output mixer 17. The output mixer 17 translates the simulated signal to the operating frequency of the radar 28 and supplies it to the input of the divider 18, from the output of which one part of the simulated signal is fed to the input of the first output UHF 20, and the other part to the input of the output FV 19, which changes the phase of the signal by π/2 and feeds it to the input of the second output UHF 21. Reinforced signals from the outputs of the first and second output UHF 20 and 21, respectively, are fed to the inputs 2 of the first and second controlled attenuators 22 and 23. The first controlled attenuator 22 and the second controlled attenuator 23 regulate the levels of the signals transmitted, respectively, through the first AP 2 and the second AP 3 to the inputs outputs 1 and 2 PPA 1, respectively, and thus determine the polarization of the emitted simulated signal. By adjusting the attenuation level of the controlled attenuators 22 and 23, the CU and RPP 14 can set different types of polarization of the emitted PPA 1 signal - horizontal, vertical, circular or elliptical.

The radar under test 28, which receives and processes the simulated signal as well as real target echoes, generates and tracks the simulated target's trajectory, classifies the simulated target, and documents the results. In the case of radiation from the UAV 27 of interference signals, the tested radar 28 operates under the influence of active interference. After the end of the flight of the UAV 27, it is determined how accurately the flight program was carried out according to the time and coordinates recorded during the flight in the memory of the UU and RPP 14, and it is also determined how well the tested radar 28 performed its functions of detecting and tracking the simulated target and its recognition. In the case of radiation from the UAV 27 of interference signals, the noise immunity of this radar is checked.

When choosing a value for the scaling factor K, the following restrictions should be considered:

- from above, since a too large value of K gives a small distance of the flight path of the UAV 27 from the tested radar 28 and, as a result, an increase in the influence of positioning errors of the UAV 27 on the accuracy of reproduction of the trajectory of the simulated target;

- from below, since too small value of K gives a large distance and high flight altitude of the UAV 27, which may be limited by its flight capabilities.

Let, for example, with a stationary test radar 28 with a sector detection zone and a height of the phase center of the antenna H _c =10 m, it is required to simulate the flight of an aerodynamic target (ATC) at an altitude of H _ADC = 10000 m at a speed V _ADC = 1000 km/h from a distance D _min =360 km to the distance D _max =410 km at a constant azimuth Az _ADC .

до

и рассчитываются как:The current range to UAV 27 varies from

before

and are calculated as:

- текущая дальность до имитируемой АДЦ.where

- current range to the simulated ADC.

The flight time for both ADC and UAV 27 is defined as:

The speed of the UAV 27 is defined as:

The azimuth of the UAV 27 corresponds to the azimuth of the simulated ADC, i.e.

The current elevation angle of the simulated ADC is determined from the triangle Center of the Earth - Phase center of the antenna of the tested radar 28 - Simulated ADC, shown in FIG. 2. According to the cosine theorem:

where R _e \u003d (4/3) R is the equivalent radius of the Earth [Handbook of radar / Ed. M. Skolnik. 1970. Trans. from English. under the general editorship. K.N. Trofimov. In 4 volumes. Volume 1. Fundamentals of radar. Ed. Yitzchoki. M.: Sov. Radio. 1976. 456 p.]; R=6371.11 km is the radius of the Earth (the Earth is represented by a sphere).

Whence the elevation angle of the simulated ADC, as well as the elevation angle of the UAV 27, is defined as:

также определяется с использованием теоремы косинусов как:The current flight altitude of the UAV is 27, given that

also defined using the cosine theorem as:

The calculated values of speed and altitude for the flight of the UAV 27 must be analyzed for their compliance with its flight capabilities. If necessary, the values of speed and altitude planned for the flight of UAV 27 can be changed by selecting the value of the scaling factor K.

In FIG. 3 shows the result of calculating the elevation angle of the simulated ADC trajectory, and Fig. 4 is the result of calculating the trajectories of the UAV 27 in the "range-height" plane to estimate the scaling factor K from below.

The formation of the flight task for the UAV 27 is carried out as follows. Based on the conditions of the far zone of the antenna of the tested radar 28, the surrounding area, the flight capabilities of the UAV 27, you should choose an appropriate scaling factor K. Then, taking into account the selected trajectory of the simulated target and the value of the coefficient K, it is necessary to calculate the initial data - the coordinates of the UAV 27 trajectory points in a spherical SC. After that, the coordinates of the points of the trajectory of the UAV 27, calculated in a spherical CS, i.e. the range, azimuth and elevation values of each given point of its trajectory must be converted into geodetic coordinates - longitude, latitude and height.

The recalculation of coordinates is carried out sequentially: the coordinates from the spherical CS are recalculated into the topocentric CS, then into the geocentric CS, and then into the geodesic CS.

Recalculation from spherical SC to topocentric rectangular SC is carried out in accordance with the formulas [Yu.S. Savrasov. Algorithms and programs in radar. M.: Radio and communication, 1985, 216 p.]:

Recalculation from topocentric rectangular SC to geocentric SC is carried out in accordance with the formula [Yu.S. Savrasov. Algorithms and programs in radar. M.: Radio and communication, 1985, 216 p.]:

- вектор-столбец координат в геоцентрической СК;where

- column vector of coordinates in geocentric CS;

- вектор-столбец координат в топоцентрической прямоугольной СК;

- column vector of coordinates in a topocentric rectangular CS;

- матрица направляющих косинусов с элементами:

- matrix of direction cosines with elements:

- широта точки стояния тестируемой РЛС 28;

- latitude of the standing point of the tested radar 28;

- вектор смещения центра топоцентрической СК относительно центра геоцентрической СК с элементами:

- displacement vector of the center of the topocentric CS relative to the center of the geocentric CS with elements:

- расстояние от центра эллипсоида вращения до фазового центра антенны тестируемой РЛС 28;

- distance from the center of the ellipsoid of revolution to the phase center of the antenna under test radar 28;

H ₃ - height of the phase center of the antenna under test radar 28;

- расстояние от центра эллипсоида вращения.

- distance from the center of the ellipsoid of revolution.

Earth to the surface of the ellipsoid of revolution at a given geocentric latitude B _s ,

- геоцентрическая широта [Ю.С. Саврасов. Алгоритмы и программы в радиолокации. М.: Радио и связь, 1985 г., 216 с.];

- geocentric latitude [Yu.S. Savrasov. Algorithms and programs in radar. M.: Radio and communication, 1985, 216 p.];

- сжатие Земного эллипсоида [ГОСТ 32453-2017. Глобальная навигационная спутниковая система. Системы координат. Методы преобразований координат определяемых точек. Введен в действие с 01.07.2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1055-ст.];

- compression of the Earth's ellipsoid [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.];

= 6378,1365 км - экваториальный радиус (большая полуось эллипсоида вращения Земли [ГОСТ 32453-2017. Глобальная навигационная спутниковая система. Системы координат. Методы преобразований координат определяемых точек. Введен в действие с 01.07.2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1055-ст.];

= 6378.1365 km - the equatorial radius (the semi-major axis of the ellipsoid of the Earth's rotation [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of determined points. Entered into force on 07/01/2018 by order of the Federal Agency for Technical Regulation and metrology dated September 12, 2017 No. 1055-st.];

- эксцентриситет меридиана;

- meridian eccentricity;

- малая полуось эллипсоида вращения Земли;

- minor semiaxis of the ellipsoid of rotation of the Earth;

- матрица направляющих косинусов с элементами:

- matrix of direction cosines with elements:

λ _radar - longitude of the standing point of the tested radar 28.

- геоцентрическую СК, плоскость

которой проходит через точку стояния РЛС 28. Затем матрица

поворачивает ось

на

(«доворачивает» ее до нулевого меридиана), завершая пересчет в Х_Г, Y_г, Z_Г - геоцентрическую СК, плоскость Х_Г0Z_Г, которой проходит через нулевой меридиан.In formula (8), the operation in parentheses transforms the coordinates from the topocentric rectangular CS to

- geocentric SC, plane

which passes through the radar station 28. Then the matrix

turns the axis

on the

(“turns” it to the zero meridian), completing the recalculation in Х _Г , Y _г , Z _Г - geocentric SC, plane Х _Г 0Z _Г , which passes through the zero meridian.

Recalculation from geocentric CS to geodetic CS is carried out as follows.

значения широты, долготы и высоты определяются по формулам [ГОСТ 32453-2017. Глобальная навигационная спутниковая система. Системы координат. Методы преобразований координат определяемых точек. Введен в действие с 01.07.2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1055-ст.]:At

the values of latitude, longitude and height are determined by the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

- эксцентриситет меридиана.where

is the eccentricity of the meridian.

значения λ определяются по формулам:At

the values of λ are determined by the formulas:

where

и Z_Г=0 значения широты и высоты определяются по формулам [ГОСТ 32453-2017. Глобальная навигационная спутниковая система. Системы координат. Методы преобразований координат определяемых точек. Введен в действие с 01.07.2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1055-ст.]:At

and Z _Г =0, the values of latitude and height are determined by the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

In all other cases, the latitude values are calculated iteratively, and after the last iteration, the height is determined by the formula [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

To organize the iterative process for calculating the latitude ϕ _n , auxiliary quantities are determined according to the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

After that, the values of b and s ₂ are sequentially calculated according to the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

где d - установленный допуск, то (п+1)-ю итерацию (14) повторяют при s₁=s₂. В противном случае

[ГОСТ 32453-2017. Глобальная навигационная спутниковая система. Системы координат. Методы преобразований координат определяемых точек. Введен в действие с 01.07.2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1055-ст.].If after the nth iteration

where d is the set tolerance, then (n+1)-th iteration (14) is repeated at s ₁ =s ₂ . Otherwise

[GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. It was put into effect on July 1, 2018 by the Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.].

The accuracy of the calculation of geodetic coordinates should be no worse than the least significant digit of the codes entered in the PNS 24. The results of the calculations show that the fifth iteration of the accuracy of calculating the latitude of the object at a height of 1000 m reaches about 10 ^-8 - 10 ^-9 , and this satisfies the existing characteristics of the systems short-range UAV navigation.

It should be taken into account that the closer to the tested radar 28 the UAV 27 is located, the more its positioning errors will affect the accuracy of simulating the selected ADC movement trajectory. Therefore, to estimate the magnitude of the scaling factor K from above, we will evaluate the influence of random positioning errors of the UAV 27 on the accuracy of the simulation of the ADC movement trajectory.

и максимальной ошибкой по высоте

относительно истинной точки положения навигационного приемника GPS/ГЛОНАСС, установленного на объекте навигации. Это означает, что одни и те же значения

и

будут приводить к разным угловым отклонениям (по азимуту и углу места) имитируемой траектории движения АДЦ относительно ее истинной траектории при различном удалении БЛА 27 от тестируемой РЛС 28. Для расчета ошибок позиционирования БЛА 27 и оценки их влияния на качество имитации, необходимо пересчитать ошибки позиционирования, задаваемые на плоскости и по высоте в ошибки позиционирования, выраженные в сферической СК. Поскольку аналитическое трансформирование распределения ошибок измерений из плоскостной СК Гаусса-Крюгера и высоты в сферическую СК, как это требуется при косвенных измерениях, затруднительно, то данная задача решается с использованием метода Монте-Карло [ГОСТ 34100.3.1-2017 ISO IEC Guide 98-3 Suppl 12008. Неопределенность измерения. Часть 3. Руководство по выражению неопределенности измерения. Дополнение 1. Трансформирование распределений с использованием метода Монте-Карло. Введен в действие в качестве национального стандарта РФ с 1 сентября 2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1066-ст.].Positioning errors in GPS/GLONASS navigation systems are given by the maximum positioning error of the navigation object by distance on the plane

and maximum height error

relative to the true point of position of the GPS/GLONASS navigation receiver installed on the navigation object. This means that the same values

and

will lead to different angular deviations (in azimuth and elevation) of the simulated trajectory of the ADC relative to its true trajectory at different distances of the UAV 27 from the tested radar 28. To calculate the positioning errors of the UAV 27 and evaluate their impact on the quality of the simulation, it is necessary to recalculate the positioning errors given on the plane and in height into positioning errors expressed in spherical CS. Since it is difficult to analytically transform the distribution of measurement errors from a planar Gauss-Kruger CS and height into a spherical CS, as required for indirect measurements, this problem is solved using the Monte Carlo method [GOST 34100.3.1-2017 ISO IEC Guide 98-3 Suppl 12008. Uncertainty of measurement. Part 3. Guidance on the expression of measurement uncertainty. Appendix 1. Transformation of distributions using the Monte Carlo method. It was put into effect as a national standard of the Russian Federation on September 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1066-st.].

The essence of the method for the problem under consideration is that during the computational experiment, samples of coordinates in the planar Gauss-Kruger system and heights are formed, which contain a constant component that determines the real position of the UAV 27 relative to the tested radar 28, and a random component due to positioning errors. Then, the resulting samples of coordinates are recalculated into a spherical CS and subjected to statistical processing in order to determine the root-mean-square positioning errors in this spherical CS.

The calculation of positioning errors of the UAV 27 in the spherical SC is conditionally divided into the following stages.

1) Recalculation of the UAV 27 coordinates from the geodetic SC into the plane coordinates of the Gauss-Kruger SC.

The connection of the geodetic CS with planar coordinates is illustrated in Fig. 7, which shows one of the six-degree Gauss-Kruger zones (projections). Recalculation of latitude ϕ and longitude λ into planar coordinates of the Gauss-Kruger SC x, y is carried out according to the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

- расстояние от определяемой точки до осевого меридиана зоны, рад;where

- distance from the determined point to the axial meridian of the zone, rad;

- номер шестиградусной зоны в проекции Гаусса-Крюгера;

- number of the six-degree zone in the Gauss-Kruger projection;

E[…] is the integer part of the number.

2) Formation of coordinate samples taking into account planar positioning errors and positioning errors in height.

The coordinates of the UAV 27 position point, taking into account in-plane positioning errors and positioning errors in height, which are caused by errors in its navigation system, are determined by the formulas:

- случайные текущие ошибки позиционирования БЛА 27 по соответствующим плоскостным координатам и высоте соответственно, обусловленные ошибками его навигационной системы;where

- random current errors in the positioning of the UAV 27 according to the corresponding planar coordinates and height, respectively, due to errors in its navigation system;

i=1…n, n - number of calculation cycles (number of samples for each coordinate).

Assuming that the distribution of positioning errors obeys the normal law, the transition from the maximum error to the root-mean-square errors in planar coordinates and height is carried out in accordance with the “three sigma” rule according to the formulas:

To implement the Monte Carlo method, random in-plane errors along the x and y axes of the Gauss-Kruger SC are formed by the formulas:

where

randn(0,1) - generator of normal random numbers with zero mathematical expectation and unit variance;

rand(0,1) - generator of random numbers distributed according to a uniform law on the interval 0…1;

n is the number of samples.

After that, the samples of planar coordinates of the UAV 27 obtained in the course of digital modeling must be recalculated into a spherical CS. To do this, it is necessary to sequentially carry out a chain of recalculations:

- recalculation of planar coordinates into geodesic SC;

- recalculation of coordinates from geodetic CS to geocentric CS;

- recalculation of coordinates from geocentric CS to topocentric rectangular CS;

- recalculation of coordinates from a topocentric rectangular CS to a spherical CS.

3) Recalculation of samples of the obtained planar coordinates of the UAV 27 in the geodetic SC.

и

характеризующие положение БЛА 27 с учетом случайных ошибок позиционирования, пересчитываются из СК Гаусса-Крюгера в геодезическую СК по формулам [ГОСТ 32453-2017. Глобальная навигационная спутниковая система. Системы координат. Методы преобразований координат определяемых точек. Введен в действие с 01.07.2018 г. Приказом Федерального агентства по техническому регулированию и метрологии от 12 сентября 2017 г. №1055-ст.]:Coordinate selections

and

characterizing the position of the UAV 27, taking into account random positioning errors, are recalculated from the Gauss-Kruger CS into the geodesic CS according to the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

- целая часть числа.where B ₀ is the geodetic latitude of the point, the abscissa of which is equal to the abscissa x of the determined point, and the ordinate is zero;

- the integer part of number.

The values of ϕ and λ obtained by formulas (19) are used - in radians.

The value of B ₀ is determined by the formula [GOST 32453-2017.

Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

where

The value of ΔB is determined by the formula [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

- вспомогательная переменная.where

is an auxiliary variable.

определяется по формуле:The value of the quantity

is determined by the formula:

4) Recalculation of samples of coordinates of the UAV 27 from the geodetic SC to the geocentric SC.

Recalculation from geodetic SC to geocentric SC is carried out according to the formulas [GOST 32453-2017. Global navigation satellite system. Coordinate systems. Methods for transforming the coordinates of the determined points. Entered into force on July 1, 2018 by Order of the Federal Agency for Technical Regulation and Metrology dated September 12, 2017 No. 1055-st.]:

- широта точки нахождения БЛА 27;where

- latitude of the location of the UAV 27;

- долгота БЛА 27 относительная;

- UAV longitude 27 relative;

- долгота точки нахождения БЛА 27;

- longitude of the location of the UAV 27;

- долгота точки стояния тестируемой РЛС 28;

- longitude of the standing point of the tested radar 28;

- высота точки нахождения БЛА 27;

- the height of the location of the UAV 27;

- радиус кривизны первого вертикала.

- radius of curvature of the first vertical.

With this recalculation, the plane X _G 0Z _G passes through the standing point of the tested radar 28.

5) Recalculation of UAV coordinate samples from geocentric CS to topocentric rectangular CS.

Recalculation from geocentric SC to topocentric rectangular SC is carried out in accordance with the formula [Yu.S. Savrasov. Algorithms and programs in radar. M.: Radio and communication, 1985, 216 p.]:

- вектор-столбец координат в топоцентрической прямо-угольной СК;where

- column vector of coordinates in a topocentric rectangular CS;

- матрица направляющих косинусов с элементами:

- matrix of direction cosines with elements:

- вектор смещения центра топоцентрической СК относительно центра геоцентрической СК с элементами:

- displacement vector of the center of the topocentric CS relative to the center of the geocentric CS with elements:

6) Recalculation from topocentric rectangular CS to spherical CS. Recalculation from a topocentric rectangular SC to a spherical SC is carried out in accordance with the formulas [Yu.S. Savrasov. Algorithms and programs in radar. M.: Radio and communication, 1985, 216 p.]:

7) Calculation of root-mean-square positioning errors of the UAV 27 in a spherical SC.

In the presence of coordinates obtained in the course of digital modeling (range D _i , azimuth Az _i and elevation angle B _i , where i=1...n), estimates of root-mean-square positioning errors of the UAV 27 in a spherical SC are determined by the formulas [E.S. Wentzel. Probability Theory. M.: Nauka, 1969, 576 p.]:

- оценка математического ожидания дальности;where

- estimation of mathematical expectation of range;

- оценка математического ожидания азимута;

- estimation of the mathematical expectation of the azimuth;

- оценка математического ожидания угла места.

- estimation of the mathematical expectation of the elevation angle.

In FIG. 8-13 shows the results of modeling errors in the positioning of the UAV 27 for two options for its location (10 ⁵ simulation cycles for each option):

- the first option: the removal of 2000 m from the tested radar 28 along the x-axis of the Gauss-Kruger SC in the north direction (Fig. 8-10);

- the second option: the removal of 12000 m from the tested radar 28 along the x-axis of the Gauss-Kruger SC in the north direction (Fig. 11-13).

The other conditions were:

- location height of UAV 27: option 1 H _UAV =15 m; option 2 H _UAV =100 m;

- latitude of the standing point of the tested radar 28

- longitude of the standing point of the tested radar 28

- the electric axis of the antenna of the tested radar 28 is directed to the north;

- height of the phase center of the antenna of the tested radar 28 N _s =10 m;

- UAV in-plane positioning error 27

- UAV positioning error 27 in height

Tables 1 and 2 show the results obtained after 10 ⁵ cycles of digital simulation. The convergence of the true values of the given coordinates and the coordinates calculated as a result of the simulation confirms the adequacy of the model to the conditions under consideration and the reliability of the simulation results.

что тоже значительно меньше ошибки измерения угловых координат большей части существующих и перспективных РЛС.From the analysis of table 2 it can be seen that the angular positioning errors decrease in proportion to the increase in the distance of the UAV 27 from the tested radar 28. At a distance of 12000 m from the UAV 27 from the tested radar 28, which corresponds to the value of the scaling factor K=30, the root-mean-square positioning errors are 0.003° in azimuth, in elevation 0.0005°. This is one or two orders of magnitude less than the errors in measuring the angular coordinates of most of the existing and prospective radars. RMS positioning error in range at K=30 will be

which is also much less than the error in measuring the angular coordinates of most of the existing and prospective radars.

Thus, for the considered example of simulating the ADC movement trajectory using UAV 27, the value of the scaling factor K - 30 is quite suitable. This also corresponds to the capabilities of modern copter-type UAVs, and eliminates the strong influence of UAV 27 positioning errors on the coordinate errors of the ADC movement trajectory simulation.

The main parameters that determine the similarity of the simulated signal emitted from the UAV 27 and the echo signal of the real ADC are: the delay time of the signal emission from the moment of receiving the probing signal of the tested radar 28; power; Doppler frequency correction; polarization; time and phase modulation.

The delay time of the emission of the simulated signal from the moment of receipt of the PPA1 of the probing microwave signal of the tested radar 28 is determined by the formula:

where c is the speed of light.

The essence of formula (27) is illustrated in Fig. fourteen.

The power of the simulated signal emitted from the UAV 27 is determined from the condition that it must create at the input of the receiving antenna of the tested radar 28 the same spectral power flux density as the echo signal of the simulated target. The spectral power flux density generated at the input of the receiving antenna of the tested radar 28 by a simulated signal emitted from the UAV 27 is determined by the formula:

where G _M - coefficient of directional action (KND) GOTA 1 for transmission;

P _I - the power of the imitation signal;

- ширина спектра ответного сигнала;

- width of the spectrum of the response signal;

L _I - loss factor in the antenna-feeder path of the simulator;

- коэффициент потерь мощности сигнала в атмосфере на линии тестируемая РЛС 28 - БЛА 27.

- coefficient of signal power loss in the atmosphere on the line of the tested radar 28 - UAV 27.

The spectral power flux density created at the input of the antenna of the tested radar 28 by the echo signal of the simulated ADC is determined by the formula:

where R _P - the power of the probing signal generated by the transmitter of the tested radar 28;

G _P - KND transmitting antenna tested radar 28;

- ширина спектра эхосигнала АДЦ;

- ADC echo spectrum width;

- ЭПР АДЦ;

- EPR ADC;

- коэффициент потерь мощности сигнала в передающем антенно-фидерном тракте тестируемой РЛС 28;

- coefficient of signal power loss in the transmitting antenna-feeder path of the tested radar 28;

- коэффициент потерь мощности сигнала в атмосфере на линии тестируемая РЛС 28 - имитируемая АДЦ.

- coefficient of signal power loss in the atmosphere on the line tested radar 28 - simulated ADC.

определяется как:From (28) and (29) it follows that the power of the imitation signal at

defined as:

So at R _p =100 kW, G _P =40 dB, L _P = -2 dB, L _ADC = -3 dB, D _ADC =400 km, σ _ADC =10 m ² , G _UAV =4 dB, L _I = -3 dB, L _UAV = -0.5 dB and D _UAV = 4 km, the power of the imitation signal will be:

The Doppler frequency correction is determined as follows. The selected trajectory of the simulated ADC is discretized with a small time interval dt, and at each of this interval the radial velocity relative to the tested radar 28 is determined by the formula:

where D _i and D _i+1 - the range of the simulated ADC relative to the tested radar 28 at adjacent sampling intervals. After that, the Doppler frequency correction for each sampling interval is determined by the formula:

where L _P is the wavelength of the signal emitted by the transmitter of the tested radar 28.

The required polarization of the emitted signals is provided by adjusting the signals applied to the inputs-outputs 1 and 2 of the PPA 1.

The phase modulation of the simulated signals must correspond to the phase modulation of the signals received from the tested radar 28.

The threshold with which the detected signals are compared, selected at the outputs of N digital filters implemented in the DSP 11, must exceed the internal noise power of the receiving path _РШ by 15-18 dB, which will ensure the probability of correct detection close to unity with the probability of false detection 10 ^{- 10} ... 10 ^-8 with a non-fluctuating signal [Handbook of radar / Ed. M. Skolnik. 1970. Trans. from English. under the general editorship. K.N. Trofimov. In 4 volumes. Volume 1. Fundamentals of radar. Ed. Yitzchoki. M.: Sov. Radio. 1976. p. 44, fig. four]. The receiving path includes PPA 1, the first AP 2, the second AP 3, the input phase shifter 4, the adder 5, the input UHF 6, the mixer 8, the input UHF 9, the demodulation unit 10, digital filters and digital detectors implemented in the DSP 11. Noise level will be determined by the bandwidth of the particular digital filter, which determines a different threshold level for each digital filter. To determine the threshold level, it is necessary to measure the noise power R _W at the output of each digital detector in the absence of probing microwave signals from the tested radar 28, determine the threshold levels based on the probability of false detection, and write these values to the memory of the DSP 11. With linear detection of normally distributed noise the distribution law of the envelope of this noise will have a Rayleigh distribution density [S.I. Baskakov. Radio engineering circuits and signals. Third edition, revised and enlarged. M.: Higher school. 2000. Formula (7.61), p. 182]:

Then the threshold level U _p is determined at a given level of false detection R _W from the equation:

Solving the equation, we get

что соответствует пороговому отношению сигнал/шум в 15,5 дБ и обеспечивает вероятность обнаружения более 0,95 при не флюктуирующем сигнале [Справочник по радиолокации / Под ред. М. Сколника. Пер. с англ. под общей ред. К.Н. Трофимова. В 4 томах. Том 1. 1970. Основы радиолокации. Под ред. Ицхоки. М.: Сов. Радио. 1976. 456 с. с.44, рис. 4].For example, for F _LO =10 ^-8 threshold value

which corresponds to a threshold signal-to-noise ratio of 15.5 dB and provides a detection probability of more than 0.95 with a non-fluctuating signal [Handbook of radar / Ed. M. Skolnik. Per. from English. under the general editorship. K.N. Trofimov. In 4 volumes. Volume 1. 1970. Fundamentals of radar. Ed. Yitzchoki. M.: Sov. Radio. 1976. 456 p. p.44, fig. four].

An analysis of the performance of the proposed method for simulating echo signals of a moving target in comparison with the prototype shows that the emission of a simulated signal from the UAV, which moves in the azimuth-elevation plane similar to the simulated target, with a delay calculated taking into account the distances of the simulated target-tested radar and UAV-tested radar , allows you to generate a simulated echo signal from any point in the detection zone of the specified radar with coordinate errors that are smaller than the errors in measuring the coordinates of most modern radars. In this case, the parameters of the simulated echo signals or interference emitted from the UAV will correspond to the parameters of the echo signals of the simulated target or the interference of the simulated jammer throughout their flight in the detection zone of the tested radar. The application of the proposed method will reduce the cost and time of testing the radar because: firstly, the UAV has a small cost both of its own and the cost of its flight time; secondly, the procedure for organizing flights based on the proposed method is simplified in comparison with the organization of flights of real aerodynamic or ballistic targets for testing radars. Thus, we can conclude that the problem is solved and the technical result of the invention is achieved.

Distinctive features of the proposed method of simulating the echo signals of a moving target provide the emergence of new properties that are not achievable in the prototype and analogues. A comparative analysis of known methods, technical solutions (analogues) in the studied and related subject areas made it possible to establish: there are no analogues with a set of features that are identical to all the features of the claimed method, which indicates that the claimed device complies with the "novelty" condition.

The results of the search for known solutions in the field of radar, radio engineering and antenna measurements in order to identify features that match the distinguishing features of the prototype of the proposed method, showed that they do not follow explicitly from the prior art. Also, the influence of the actions provided for by the essential features of the claimed invention on the achievement of the specified technical result has not been revealed. Therefore, the claimed invention meets the condition of patentability "inventive step".

The invention is "industrially acceptable", since the proposed method can be implemented on the existing element base to simulate the signal-to-noise radar environment during radar testing.

Claims (1)

A method for simulating echo signals of a moving target in the detection zone of a tested radar, which consists in the fact that in the simulator, probing microwave signals of the tested radar are received, their amplitude is limited by an attenuator, amplified in a high-frequency amplifier, converted to an intermediate frequency (IF), characterized in that that the signals converted to the IF are subjected to matched filtering in N filters, where the impulse response of a certain filter corresponds to a certain modulation variant of the probing microwave signal of the tested radar, the signals extracted at the filter outputs are detected, they are compared with the threshold, the type of the probing microwave signal of the tested radar is determined, choosing the maximum from signals that exceed the threshold, form a signal on the IF with modulation corresponding to the impulse response of the filter in which the maximum signal was selected, with a delay relative to the probing signal of the tested radar, corresponding to the distance between the simulator and the simulated movement with a shift of the carrier frequency by the value of the Doppler shift determined by the radial velocity of the simulated target, and with amplitude modulation corresponding to the range to the simulated target, its effective scattering surface and random fluctuations characteristic of this type of simulated target, convert the generated signal to the carrier frequency of the radar under test, divide the generated microwave signal into two components, phase-shift one component of the microwave signal by an angle π/2, adjust the amplitude of each component so as to ensure the radiation of the microwave signal with a given polarization, feed one component to the first input-output, and the other component - to the second input-output of the two-input receiving-transmitting antenna, oriented in the direction of the tested radar, and radiate with polarization corresponding to the polarization of the echo signal of the simulated target, and the simulator is placed on an unmanned aerial vehicle (UAV), equipped with a flight and navigation system, providing and its flight in the far zone of the antenna of the tested radar with movements during the flight in the azimuth-elevation plane, similar to the movements of the simulated target, and in range and at speed - with the values of the range and flight speed of the simulated target reduced by K times, where the value of K is selected, based on the capabilities of the UAV in terms of height and speed of its flight.

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