RU2741057C1 - Method of radar recognition of classes of aerospace objects for a multi-band spaced apart radar system with phased antenna arrays - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to methods of obtaining radar information (RI) on aerospace objects and can be used for detection and radar identification of classes (RIC) of aircraft in radar systems (RS) as part of radar modules (RM) of different wavelength range with phased antenna arrays (PAA), which can be combined into bistatic radars for combined information processing. That is ensured by integration into a single radar system of RMs operating in different wavelength ranges at a combined position and RMs of the same wavelength ranges located at spaced positions and using reusable radar. RS data can operate in both passive and active modes, or can be mutually switched according to a predetermined program (by random or deterministic law). Forming several fan-shaped spatial receiving channels in the direction overlapping the active RM detection range lost due to radioelectronic suppression, and processing information from corresponding ranges for each of the formed channels.

EFFECT: technical result consists in preservation of detection range and increase of probabilities of correct recognition of radar objects.

1 cl, 4 dwg, 1 tbl

Description

The invention relates to methods for obtaining radar information about aerospace objects (VKO) and can be used for the detection and recognition of classes (RRK) VKO in radar complexes (RLK) as part of radar modules (RLM) of different wavelengths with phased antenna arrays (PAR), which can be combined into bistatic radars for joint information processing.

The proposed technical solution relates to the field of defense technology, in particular to radar stations with phased array, and can be used to organize air defense of troops and military objects from being hit by enemy air attack weapons in conditions of electronic suppression.

The technical result of the claimed invention is to maintain the detection range and increase the probabilities of correct recognition of radar objects.

The result is achieved due to the integration into a single radar system of RLM operating in different wavelength ranges at a co-located position, and RLM of the same wavelength ranges, located at separated positions and using the capabilities of multiple reflected radar.

Known methods RRK VKO, which use various signs (dictionaries of signs) for recognition [1, 2, 3]. In this case, the primary is the definition of the limited alphabet of the aerospace defense classes [1, 2], then the assessment of the air target is carried out by the used recognition criteria and the further identification of the class of this target.

The most applicable trajectory signs, signal signs, intrinsic radio emission, complex characteristics of aerospace defense. In specific types of RLK, RLM, as a rule, multi-stage RRK procedures are used, analyzing several signs sequentially. The most accessible from the point of view of obtaining information are trajectory signs (EKO coordinates, parameters of their movement, rate of change of coordinates and movement parameters, maneuverable characteristics). The boundary values of the trajectory features are determined for each a priori set to the RRK EKR, the finding of the EKR in the space of possible values of each feature allows the primary RRK to be carried out. Aerospace defense classes such as helicopters, cruise missiles (CR), hypersonic aircraft (GZVA), automatic drifting balloons (ADA) do not intersect in the space of trajectory signs (speed and flight altitude), they are correctly recognized with a high probability, since it differs significantly itself the physical nature of the possibility of movement of these classes in airspace.

However, there is a sufficient number of aerospace defense classes that can simultaneously be in the given feature spaces (small, medium and large aircraft at the stationary flight stage), and are not correctly recognized with the required quality by trajectory features (Fig. 1). In such cases, recognition continues by signal signs, the simplest of which is the effective scattering surface (ESR).

Trap missiles (decoys) are most difficult to recognize by the RCS value and trajectory characteristics. Trap missiles imitating the tractor features of the most dangerous aerospace defense (tactical, carrier-based, strategic aircraft), booby-trap missiles are small and have a small RCS, and special devices (Luneberg lenses, Van Atta reflectors) are used to simulate RCS, which increase the RCS. For the recognition of booby traps, there are methods based on the determination of the size of the aerospace defense by signal signs.

The closest in technical essence is the method for recognizing VKO in multi-band radars (MDRLK), implemented in the VKO recognition device in dual-band radars with active phased array (RF patent No. 2665032 C2, IPC G01S 13/52, publ. 08/27/2018) (prototype ) [4]. The present invention proposes to use modern radar technologies of adaptive interaction of RLM of different wavelength ranges, which allow for two-stage recognition with pulse-by-pulse frequency tuning in dual-band complexes to significantly reduce the time spent on solving the recognition problem.

The technical result of the prototype is to improve the tactical and technical characteristics, which consists in a significant decrease in the recognition time, an increase in the range of information output about the recognized target class, which will further increase the alphabet of recognizable aerospace defense classes (especially high-speed ones) with a sufficiently high level of probability and reliability of correct target class recognition, which is achieved by using adaptation of the frequencies of the probing signal for recognition based on the longitudinal size of the target.

The disadvantage of the prototype is the insufficient detection range and the impossibility of the RRK VKO under conditions of electronic suppression (REB) by active noise interference (ACP) used both from the ground, in the form of dropped jamming transmitters, and from the air, in the form of specialized equipment installed on aircraft, unmanned aerial vehicles , missiles, as a result of which the channels of detection, selection by range and speed are suppressed in the radar, as well as at high interference power, angular selection becomes difficult due to their effect on the side lobes of the receiving antenna.

When the enemy organizes a REB, multi-beam systems for creating ACP are used, antennas with radiation patterns in the azimuth plane with a width of no more than 15 ° and a gain of up to 20 dB are used. Thus, the interference is narrowly directed in space, which allows the use of joint processing of information from spaced-apart radar stations (RLM) to maintain their effectiveness in the case of REB.

The known method of radar surveillance of space, based on the interaction of spaced apart radar stations included in a multi-position radar system (V. Ya. Averyanov. Spaced radar stations and systems. Minsk, "Science and Technology", 1978, pp. 52-74) [ five]. The advantage of such a system is that it is very difficult to create directional interference for spaced radars, since the direction from the source of active interference to the non-radiating position is often unknown. A stimulated emission in a wide sector reduces the power flux density of interference acting on each position (VS Chernyak. Multi-position radar. M., "Radio and Communication", 1993, pp. 28-29) [6].

However, the disadvantage of this method is significant energy consumption when viewing the space, since all stations of the system must simultaneously inspect each section of the viewing area, including the "empty" directions (in which there are no targets and no interference), and cannot be used as independently operating spaced radars. As a result, this leads to a significant decrease in the coverage area of the radar system, which consists of radar data for a given coverage period, or an increase in the coverage time of a given area, i.e. exceeding the established energy resource during the review period.

There is a known method for surveying space by radar stations with phased antenna arrays (RF patent No. 2646847 C2, IPC G01S 13/02, publ. 03/12/2018) [7], which allows, on the basis of energy differences, interference signals observed at spaced reception points of each RLM, to review the space by choosing the option for viewing the angular position, as a result of which the directions in which the confident detection of targets at the required range is ensured, the space survey is carried out by a single-position radar, and the directions in which the power flux density of the active jammer does not ensure target detection at the required range, are probed by spaced radars, providing the maximum number of resolution elements in the radar viewing area under conditions of ACP exposure, examined with a given detection quality with a limited energy resource.

The disadvantages of this method are not to use the possibility of maintaining the detection range of a single-position radar in the RLM of two or more wavelength ranges, and not to use the possibility of obtaining additional signs of RRK EKR due to the multi-position RLM (RLK), combined in the MRLK with the REB.

The developed method allows to eliminate the indicated disadvantages.

The essence of the proposed method of radar recognition of aerospace defense is as follows.

At the first stage, several single-position radars are installed at the given positions, which contain radars of different wavelength ranges, which are part of a single radar system, and mutual coordinate referencing of all system means is carried out, i.e. exchange of the corresponding values X ₁ , Y ₁ , Z ₁ , X ₂ , Y ₂ , Z ₂ , X _n , Y _n , Z _n . After the completion of the procedure for mutual coordinate referencing of the radar, the process of searching, detecting and tracking airborne objects in the specified field of view begins.

At the second stage, information from the detected RLM of the meter and decimeter (centimeter) wavelength range of the EKO echo signals, containing the range, azimuth, elevation and amplitude of echo signals at each sounding frequency, as well as information about the state ownership of the EKO, is sent to the radar processing unit, in which further recalculation of coordinates into a rectangular system, tie-in of the track along the EKR, binding of the detected echo signals to the existing tracks, the speed of the EKR is measured along the coordinates x and y (V _x , V _y ) generalized from two modules and its height (H _i ), and the recalculation is also carried out route priority.

At the third stage, the value of the vertical velocity component (V _Hi ) is determined by the formula:

Where:

Δt - time interval between measurements of heights H _i and H _{i + 1}

At the fourth stage, the value of the track speed VKO (V _Ti ) is calculated by the formula:

At the fifth stage, on the basis of the previously obtained calculations, a preliminary RRK EKR is carried out according to the trajectory signs. In this case, the information about the altitude of the aerospace defense, its vertical component of the speed and the route speed is compared with a priori given information about the possible values of these attributes for each target class. For this, a priori information is pre-laid in the form of coordinates of points of the planes "track speed - height" and "vertical component of speed - height", which limit the range of possible values of these signs for each class of aerospace defense. Then, the hit of the values of the current components of the vertical speed, route speed and flight altitude of aerospace defense in the range of possible values of the corresponding planes for each of the recognized aerospace defense classes is estimated.

If, based on trajectory signs, the final decision on the belonging of the aerospace defense to a certain class cannot be made or the probability of such recognition is insufficient, then further recognition is carried out according to signal signs: the RCS of the aerospace defense and its longitudinal size.

At the sixth stage, recognition takes place according to the RCS values of the aerospace defense, which are estimated on the basis of data on the range and elevation angle of the target, the amplitude of its echo signals and the a priori dependence of the target range with RCS 1 m ² on the elevation angle [8].

At the seventh stage, recognition takes place by the longitudinal size of the aerospace defense, which is calculated based on the analysis of the amplitudes of the echo signals of targets at each frequency, obtained during multifrequency sounding. For this, when a multi-frequency signal is emitted in each RLM of a multi-range RLK, the frequency of signal sounding is reconstructed from pulse to pulse according to a predetermined periodic law.

As indicated in the prototype [4], the time spent on measuring the longitudinal size of the VKO associated with long-term contact with the aim of accumulating the echo signal at each frequency can be significantly reduced when the measurement is implemented in a radar with a two-module construction in two steps. Moreover, the greatest boundaries for the issuance of information about the target class and the probabilities of correct recognition can be achieved in dual-band radars of meter-decimeter or meter-centimeter wavelengths.

At the first step of the seventh stage of the RLM of the meter wavelength range, a rough estimate of the longitudinal dimension is made, which is carried out by sounding at two frequencies with pulse-by-pulse frequency tuning and further calculation and averaging of the frequency recognition feature. At the same time, knowing the distance between frequencies, it is possible to calculate the largest unambiguously measured longitudinal size of the VKO (L _max ) by the formula:

Where:

c is the speed of propagation of electromagnetic waves;

Δƒ is the distance between frequencies.

Also, having determined the frequency tuning range (ΔF), according to the Kotelnikov theorem, you can calculate the smallest longitudinal size of the VKO:

Thus, according to the frequency feature of recognition, it is possible, within the range of the most common aerial objects from 4 m (aircraft missiles) to 50 m (large-sized aircraft), to distinguish three groups of aerospace defense: small-sized air object - longitudinal size from 4 to 12 m, medium-sized air object - longitudinal size from 12 to 25 m and large-sized air object - longitudinal size from 25 to 50 m.

The number of radiated frequencies required to measure the longitudinal dimension is determined by the formula:

The values of the distances between frequencies, frequency ranges and their number for accurate measurement of the longitudinal size of the EKO and further determination to one of the groups are given in the table.

At the second step of the seventh stage, having determined the optimal frequency range and frequency step based on a rough estimate of the longitudinal size of the meter range radar and knowing the coordinates of the target, accurate measurements of the longitudinal size are made by a short-wavelength radar module (centimeter or decimeter) with active phased array and two-dimensional electronic scanning, making long-term contact with the target in the mode of the beam stopped on an airborne object. In this case, it becomes possible to form narrow antenna directivity patterns, both in the azimuth and elevation planes, which ensures high measurement accuracy of trajectory, tactical and signal recognition signs. Also, this approach makes it possible to identify airborne objects with special devices that change the EPR (Luneberg lenses, Van Atta reflectors).

FIG. 2.A diagram of the construction of a dual-band radar system is presented, consisting of an RLM meter and RLM decimeter wavelength range, with the following designations:

D _MAX MM - maximum detection range of an airborne object with RCS σ RLM meter wavelength range;

- максимальная дальность обнаружения воздушного объекта с ЭПР σ РЛМ метрового диапазона волн при воздействии АШП;

- the maximum detection range of an airborne object with RCS σ RLM of the meter wavelength range when exposed to ACP;

D _TP MM - the area of space where the detection of air objects with RCS σ under the conditions of ACP exposure by single-position radar of meter wavelength range is impossible;

D _MAX DM is the maximum detection range of an airborne object with RCS σ RLM of the decimeter wavelength range;

- максимальная дальность обнаружения воздушного объекта с ЭПР σ РЛМ дециметрового диапазона волн при воздействии АШП;

- maximum detection range of an airborne object with RCS σ RLM of decimeter wavelength range when exposed to ACP;

D _TP DM is a region of space where the detection of air objects with RCS σ under conditions of ACP exposure by a single-position radar of the decimeter wavelength range is impossible.

Since the process of calculating the longitudinal size is resource-intensive, it is proposed to implement it when recognizing the most priority targets, or not recognized by other features.

In the case of the enemy's use of intensive electronic warfare, as one of the most significant and relatively cheap ways to reduce the effectiveness of the radar reconnaissance system and the air defense system as a whole, the detection range of aerospace defense and, accordingly, the range and probability of correct recognition of the class of this object are significantly reduced. In this case, it is proposed to use joint processing of information received from spaced-apart radar complexes, which can also be multi-band. Moreover, the radar data can operate in both passive and active modes, or mutually switch from active to passive mode of operation according to a predetermined program (according to a random or deterministic law).

When the enemy is exposed to electronic suppression for external cover, information from RLM located in other positions begins to be used. For this, at the eighth stage, the coverage area of the spaced radar system is initially determined, within which it is possible to conduct radar surveillance of the aerospace defense (VS Chernyak. Multi-position radar. M., Radio and Communication, 1993, p. 59, vyr. 3.2-3.3) [6]:

Where:

Р _СР (β, ε) - the average power emitted by the transmitting antenna of the RLM in the direction β, ε;

t _obl (β, ε) - exposure time;

G _TX (β, ε) - transmitting antenna gain;

G _PRM (β, ε) - gain of the receiving antenna;

σ - effective reflective surface of an airborne object;

λ is the wavelength;

ν is the distinguishing factor;

Р _w - power of the receiver's own noise;

R _p is the power of the interference signal;

KR - coefficient that takes into account the attenuation of the signal in the atmosphere;

g _pc ⁴ - coefficient that takes into account the influence of the underlying surface on the echo reflected from the target.

The area of space (D _TP ), where the detection of air objects under conditions of ACP exposure to a single-position radar is impossible, is determined by the expressions:

Accordingly, the power of the interference signal level at the input of the RLM receiver (P _p ) and the power of the own noise of the RLM receiver (P _sh ) are determined as follows [9]:

Where:

g _nc ² - coefficient taking into account the influence of the underlying surface on the interference signal;

R _PAP is the power of the jammer;

G _PAP - gain of the transmitting antenna of the interference transmitter in the direction of the RLM;

D _PAP - removal of the jammer from the RLM

Where:

k = 1.38 * 10 ^-23 J / deg - Boltzmann's constant;

T ₀ = 293 K - Kelvin temperature;

W is the receiver noise figure;

Δƒ _PRM - bandwidth of the RLM receiving device

As can be seen from the expression for the compression ratio (K _comp ), the use of interference by the adversary with a power comparable to the power of the receiver's own noise reduces the capabilities of a single-position RLM in range by 16 percent, the use of an ACP of higher power can significantly reduce the detection range and further recognition of aerospace defense.

Thus, at the ninth stage, further determination of the range, phase coordinates, state ownership and RRK VKO is carried out with joint processing of radar images, within the range of the MPRLK. Moreover, recognition can be carried out on the basis of signal processing of both spaced-apart long-wave RLM and spaced-apart short-wave RLM, as well as on the basis of processing signals received by the long-wave RLM from the short-wave RLM and vice versa. With such an implementation of signal processing, additional recognition signs appear.

It is known that the use of an additional recognition feature (expansion of the feature dictionary) with a constant volume of the alphabet of classes leads to an increase in the probability of correct recognition [1].

Maintaining the maximum range of radar reconnaissance (D _MAX ), increasing the accuracy of determining the coordinates of the aerospace defense and the likelihood of its correct recognition is ensured when using a phased array in the receiving passive RLM due to the formation of several fan-shaped spatial receiving channels in directions overlapping the detection range of the active RLM ( D _TP ), and processing information from the corresponding range samples for each of the generated channels. The diagram is shown in Fig. 3.

РЛК по половинной мощности около 1 градуса, размеры импульсного объема в азимутальной плоскости (δβ) и в угломестной плоскости (δε), соответствующие разрешающей способности РЛМ по угловым координатам, на дальности 100 км составляют 1750 м, на дальности 200 км - 3490 м, на дальности 300 км - 5230 м, что не позволяет однозначно производить селекцию целей и правильное РРК. В свою очередь, разрешающая способность по дальности (δd) при длительности импульса зондирующего сигнала 1 мкс составляет 150 м, и в настоящее время при обработке эхосигнала имеется возможность сократить длительность импульса и соответственно разрешающую способность по дальности до десятком метров. Таким образом, уменьшить импульсный объем V, изначально ограниченный разрешающими способностями по угловым координатам и дальности, возможно до V_МП при использовании разрешающих способностей по дальности от двух разнесенных в пространстве РЛМ, объединенных в единый МПРЛК (Фиг. 4).With the width of the main beam of the antenna patterns

RLK at half power about 1 degree, the dimensions of the pulse volume in the azimuthal plane (δβ) and in the elevation plane (δε), corresponding to the RLM resolution in angular coordinates, at a distance of 100 km are 1750 m, at a distance of 200 km - 3490 m, at range of 300 km - 5230 m, which does not allow to unambiguously select targets and correct RRK. In turn, the range resolution (δd) with a probe signal pulse duration of 1 μs is 150 m, and at present, when processing an echo signal, it is possible to reduce the pulse duration and, accordingly, the range resolution to tens of meters. Thus, it is possible to reduce the impulse volume V, initially limited by the resolution in angular coordinates and range, up to V _MP when using the resolution in the range from two spaced RLM combined into a single MPRLK (Fig. 4).

Also, one of the advantages of the proposed technical solution is to increase the secrecy of the radar system in conditions of a radar conflict by organizing a periodic change of the space survey option (transition from active to passive mode of operation) synchronously according to a random or deterministic law in order to reduce the duration of radiation by a specific radar or radar system.

Integration into a single radar complex of RLCs with different wavelength ranges and adaptive interaction of spaced RLMs also makes it possible to improve a number of basic parameters of the complex (expand the alphabet of target classes, increase the recognition reliability, reduce the likelihood of confusion of target classes) and, thereby, provide more efficient solution of tasks assigned to the radar.

In this method, there is no significant complication of the system, since the addition of recognition signs obtained on the basis of processing signals of different wavelengths of a single-position radar, and their further use in spaced-apart radars, only affects the software implemented on the computers, which is not a problem in the conditions of modern computing power. At the same time, the proposed method for recognizing the ICO does not require the use of a complex ultra-wideband signal.

The main condition for the implementation of the proposed RRM method is the presence of a digital PAA for reception, which allows to simultaneously form in space in the azimuthal and elevation planes a fan-shaped directional pattern that overlaps the possible ranges of finding air objects irradiated by an active radar, as well as a system for transmitting information from an active radar to a passive radar MDRLK about the direction and parameters of sensing a certain area of space. Active radar (RLM) can carry out both regular and adaptive survey of space.

The proposed technical solution is industrially applicable, since it is based on the well-known achievements of electronic technology and is intended for the detection and radar recognition of classes of aerospace objects in radar complexes.

Information sources

1. Selection and recognition based on location information / A.L. Gorelik, O.V. Krivosheev, S.S. Epstein; Edited by A.L. Gorelik. - M .: Radio and communication, 1990. - 240 p., Ill.

2. Nebabin V.G., Sergeev V.V. Methods and techniques of radar recognition. - M .: Radio and communication, 1984 .-- 152 p., Ill.

3. Handbook on radar / Ed. M.I. Skolnik. Per from English. Ed. B.C. Willows. In 2 books. Book 1. Moscow: Technosphere, 2014., - 672 p., Ill. Book 2. Moscow: Technosphere, 2014., - 680 p., Ill.

4. RF patent No. 2665032 C2, IPC G01S 13/52 "Device for recognizing aerospace objects in dual-band radar systems with active phased antenna arrays (AFAR)", publ. 08/27/2018 (prototype).

5. V. Ya. Averyanov. Spaced apart radar stations and systems. Minsk, "Science and Technology", 1978, p. 52-74.

6. Chernyak B.C. Multi-position radar. - M .: Radio and communication, 1993. - 416 p .: ill.

7. RF patent No. 2646847 C2, IPC G01S 13/02 "Method for viewing space by radar stations with phased antenna arrays", publ. 03/12/2018 (analogue).

8. Skolnik M.I. Handbook of Radar, Volume 1. Moscow, "Soviet Radio", 1976, pp. 356-395.

9. Yu.M. Perunov, K.I. Fomichev, L.M. Yudin. Electronic suppression of information channels of weapons control systems. M., "Radiotekhnika", 2003, p. 46.

Claims (1)

A method of radar recognition of aerospace objects (VKO) classes for a multi-band spaced apart radar complex (RZ) with phased antenna arrays (PAR), in which the processing of radar information (RI) is carried out by starting the process of searching, detecting and tracking VKO in a given field of view, information about the VKO echo signals detected by radar modules (RLM) of the meter and decimeter wavelength range, containing the range, azimuth, elevation and amplitude of echo signals at each sounding frequency, as well as information about the state ownership of the VKO, is sent to the radar processing unit, in which further recalculates the coordinates into a rectangular system, determines the value of the vertical component of the velocity (V _Hi ), calculates the value of the track velocity of the aerospace defense (V _Ti ), based on the previously obtained calculations, preliminary radar class recognition (RRK) of the aerospace defense is carried out by trajectory features, pr and this is the comparison of information about the altitude of the aerospace defense, its vertical component of the speed and the route speed with a priori given information about the possible values of these features for each class of target, and if the final decision on the belonging of the aerospace defense to a certain class cannot be made based on the trajectory features or the probability of such recognition is insufficient, then it is recognized by the values of the effective scattering surface (ESR) of the aerospace defense, which are estimated based on the data on the range and elevation angle of the target, the amplitude of its echo signals and the a priori dependence of the target's range with the RCS, then it is recognized by the longitudinal size of the aerospace defense, which is calculated based on analysis of the amplitudes of target echoes at each frequency of the RLM long-wavelength range for preliminary determination of the size of the VKO, and accurate determination of the size of the RLM short-wavelength range of wavelengths with an active phased array, making long-term contact with the target in the mode of a beam stopped on an air object and its recognition with b a higher probability, and in the case of the use of electronic suppression (REP) and a decrease in the maximum range of radar reconnaissance by a single-position radar, the use of multi-band spaced radars that can operate in both passive and active modes, or mutually switch according to a predetermined program , and recognition can be carried out on the basis of signal processing of both spaced-apart long-wave RLM and spaced-out short-wave RLM, characterized in that they integrate RLM of different wavelength ranges at combined and spaced positions into a single radar system by mutual coordinate referencing of all system means and joint processing of radar images received by each radar, while the presence of a digital active phased array, working for reception, allows you to simultaneously form in space in the azimuthal and elevation planes a fan-shaped radiation pattern that overlaps the possible The ranges of finding air objects irradiated by an active radar allows, due to the multi-positionality, to reduce the pulse volume, to maintain the detection range and range of the aerial missile defense system in conditions of REB by active noise interference, to obtain additional recognition signs and to increase the likelihood of a correct aerial missile defense system.

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