RU2458358C1 - Goniometric-correlation method of determining location of surface radio sources - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used when determining location of surface radio sources. The disclosed method involves measurement of eigen coordinates x(k), z(k) on-board direction-finding aircraft using an inertial navigation system, the heading angle y(k) and the bearing of the radio source φ_s(k); an on-board computer system breaks down the area around the radio source with roughly determined Cartesian coordinates x_i, z_i into rectangles with coordinates of centres x_i z_i; for each rectangle and all direction-finding points, the expected values of bearings φ_ij(k) are calculated using the formula

where x(k), z(k) are coordinates of the direction-finding aircraft at the k-th point of finding the direction of the radio source, X_i(k), Z_j(k) are coordinates of the centre of the rectangle, ψ(k) is the heading of the direction-finding aircraft at the k-th point of finding the direction of the radio source; the extremum of the cross-correlation function realisation of φ_s(k) and φ_ij(k) or the quality functional

is calculated, where K is the number of direction-finding points, g(k) is the weight coefficient, φ_s(k) is the measurement of the bearing of the radio source, φ_ij(k) is the calculated bearing value; coordinates of the radio source are calculated and then delivered to consumers.

EFFECT: high accuracy of determining location of surface radio sources and shorter time spent on obtaining acceptable results in single-position direction-finding systems.

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Description

The invention relates to radar and can be used to improve the accuracy of determining the location of ground-based sources of radio emission (IRI) in passive modes of operation of radar stations or radar reconnaissance stations (SRTR).

The main source of information about the air and ground conditions on various aircraft, including military ones, are airborne radar (RLS), radio navigation (RNS) and radio communication (RCC) systems.

Simultaneously with the development of these systems, radio-electronic suppression (RE) means are also being developed to disrupt the operation of all types of radio systems. In this regard, ground-based radio-electronic suppression systems are becoming priority targets for attack aircraft in combat operations, subject to priority destruction. However, to defeat these targets, you must know their location (coordinates). To solve this problem, it is necessary to know the range to them and their airborne bearings, as well as their derivatives. It should be noted that with the suppressed rangefinder channels of the airborne radars, it is possible to measure only airborne bearings on the sources of radio emission (IRI) in the passive mode of operation of the radar itself or SRTR.

In addition, a very important class of targets themselves are terrestrial radio communication systems, radio navigation, guidance, etc., which are sources of radio emission and also subject to priority destruction.

In connection with the noted very important informational task, it is to determine the location of Iran using goniometric data. This problem can be solved by a large number of methods, an overview of which is given in [1].

Among these methods, one of the most used is the triangulation method, based on the double (multiple) direction finding of the IRI after a certain time with measuring the distance flown by the plane during this time [2]. The essence of this method, taken as a prototype, explains figure 1. This figure shows the position of the direction-finding aircraft, located at time point t ₁ at point O _C1 and moving at a speed V at an angle φ ₁ to the IRI, measured by the direction finder. After some time, Δt = t ₂ -t ₁ , where t ₂ is the moment the aircraft was at point O _C2 , a second measurement of the angle φ ₂ on the IRI is carried out with the measurement of the distance L = O _C2 O _C1 , which is carried out in a known manner or by calculating the coordinates by navigation systems, or in accordance with the ratio

L = V (t ₂ -t ₁ ).

Using the triangulation method allows you to calculate the coordinates of the ground Iran using the formulas [2]

The bearing path of the direction finding aircraft must satisfy two conditions.

Firstly, we cannot allow the situation when φ ₂ = φ ₁ .

Secondly, to increase the accuracy of direction finding, it is necessary to have bearing values that significantly exceed the values of the errors of their measurement.

However, it should be noted that all existing methods for determining the location of ground-based IRI used in single-position systems have low accuracy and require long-term maneuvering of the aircraft in a horizontal or vertical plane [1].

The proposed goniometric-correlation method allows to solve the problem of radically increasing the accuracy of determining the location of ground-based IRI and reducing the time spent on obtaining acceptable results in single-position direction finding systems.

The essence of the angular-correlation method of estimating the coordinates of the IRI is as follows. Aircraft (LA), equipped with radar or SRTR, flies along a given path. At the moments k of receiving the IRI signals on the aircraft, the aircraft’s bearing φ _and (k) of the target, the course ψ (k) of the aircraft and its rectangular coordinates x (k), z (k) are measured. Reception of signals can occur periodically or occasionally depending on the evolving tactical situation. The number k of direction finding points on the aircraft trajectory should be such that it would be possible to obtain estimates of the coordinates of the IRI with an accuracy not worse than the given.

пеленгов начинается процедура оценивания прямоугольных координат целей. Для этого участок местности вокруг грубо определенных координат x_ц, z_ц разбивается на I×J прямоугольников, размеры которых зависят от размеров анализируемого участка, требуемой точности определения местоположения ИРИ и возможностей вычислительной системы, установленной на ЛА (фиг.2). Каждому прямоугольнику ставятся в соответствие координаты x_i, z_j его центра. Затем для каждого прямоугольника и всех точек пеленгации рассчитываются ожидаемые значения бортовых пеленгов по формулеAfter collecting a certain number of measurements φ _and (k)

Bearings begins the procedure for evaluating the rectangular coordinates of targets. For this, the terrain around roughly defined coordinates x _c , z _{c is} divided into I × J rectangles, the sizes of which depend on the size of the analyzed area, the required accuracy of determining the location of the IRI and the capabilities of the computing system installed on the aircraft (Fig. 2). Each rectangle is associated with the coordinates x _i , z _{j of} its center. Then, for each rectangle and all direction finding points, the expected values of the directional bearings are calculated by the formula

where x (k), z (k) are the coordinates of the aircraft at the k-th point of direction finding of the IRI;

ψ (k) is the aircraft course at the k-th point of direction finding of the IRI.

и φ_ij(k). Экстремум этой функции будет свидетельствовать о совпадении текущего местоположения ИРИ с элементарным участком местности, координаты которого известны с высокой точностью.After this, the search begins for the elementary site (possible location of the IRI), which corresponds to the set of measured values of bearings. The degree of proximity of the calculated and measured values of bearings can be determined by the value of the cross-correlation function of the implementations φ _and (k)

and φ _ij (k). The extremum of this function will indicate the coincidence of the current location of the IRI with an elementary area, the coordinates of which are known with high accuracy.

The search procedure can be performed in various ways. The simplest of them is a sequential comparison of the current set of measured values of bearings φ _and (k) with the calculated φ _ij (k) corresponding to all elementary sections of the terrain with a shift by one element in rows and columns. However, this method requires high-speed computing system. Otherwise, a lot of time is spent searching.

It should be noted that as a quality functional characterizing the degree of correspondence of the current set of bearings {φ _and (k)} and their calculated {φ _ij (k)} analogues, not only the cross-correlation function can be used, but also significantly simpler in Computationally, the weighted sum of the squared differences of the current measured and calculated values. In such cases, the criterion for the coincidence of the current implementation of bearings and their calculated values is the minimum of functionality

where K is the number of direction finding points;

g (k) is the weight coefficient.

An example of changing the values of Ф _ij when calculating it for different values of x _i , z _{j is} shown in Fig.3.

With fairly small sizes of elementary terrain with a center x _i ≈x _IRI , z _j ≈z _IRI , very high accuracy can be obtained.

The information-computer system (IVS) of the direction-finding aircraft, which implements the goniometric-correlation method (3), (4), should include meters (algorithms for generating estimates) of the IRI on-board bearing, aircraft course, and also the navigation system with which to measure rectangular coordinates of the aircraft in a particular coordinate system.

Figure 4 presents a simplified structural diagram of a possible variant of a system that implements the above-described angular-correlation method.

The system includes: inertial navigation system (ANN) (satellite navigation system - SNA) 1; course meter 2; airborne radar system (radar) (radio intelligence station - SRTR) 3; airborne computing system (BVS) 4.

The technical result that can be obtained by implementing the proposed method is to realize the possibility of high-precision location of ground-based sources of radio emission with significantly less time spent on obtaining acceptable results.

The specified technical result is achieved by the fact that on board the direction-finding aircraft, the eigenvalues of the location x (k), z (k) are simultaneously measured using the ANN (SNA), the heading angle ψ (k) using the heading meter, target bearing φ _and (k ) using the radar direction finder (SRTR), the BVS splits the area around Iran with roughly defined rectangular coordinates x _c , z _c into rectangles with the coordinates of the centers x _i , z _i , for each rectangle and all direction finding points, the expected values of bearings φ _ij (k) on forms le (3) is determined extremum mutually-correlation function realization φ _and (k) and φ _ij (k) or quality of the functional F _ij (4), which leads to the determination precision coordinates x _IRI, z _IRI, which are then fed to consumers.

The principles of building radar systems (SRTR) and navigation systems (ANN, SNA) of an airplane are known and described in detail in the literature [3, 4].

Figures 5 and 6 show the root-mean-square errors of determining the location of ground-based IRI in the traditional way by formulas (1), (2) and the proposed goniometric-correlation method based on minimizing functional (4), respectively, with unit cell sizes 500 × 500 m and 300 × 300 m under the following conditions: number of cells - 11; the interval between measurements of bearings of the target is 10 s; direction finder flies at a constant speed V _C = 200 m / s; Standard deviation of direction finder errors σ _φ = 0.2 °; the number of implementations is 100.

From figures 5 and 6 it is seen that the proposed method provides an increase in the accuracy of positioning up to 10 ... 100 times. Moreover, the time to obtain acceptable accuracy is reduced by two to three times. It should be noted that with a decrease in the size of the unit cell, the accuracy of determining the location of the IRI improves.

Implementation of the method described above will allow highly accurate estimation of the location coordinates of ground-based sources of radio emission with significantly higher accuracy and in significantly less time compared to other existing methods of single-direction finding.

LITERATURE

1. Drogalin V.V., Merkulov V.I., Chernov V.S. et al. Determination of coordinates and motion parameters of sources of radio emissions from goniometric data in single-position onboard radar systems. // Foreign radio electronics. Successes of modern radio electronics. - 2002. - No. 3.

2. Drogalin V.V., Merkulov V.I., Chernov V.S. et al. Methods for assessing the accuracy of determining the location of radio emission sources by a passive goniometric on-off airborne radar system. // Foreign radio electronics. Successes of modern radio electronics. - 2003. - No. 5.

3. Kanaschenkov A.I., Merkulov V.I., Gerasimov A.A. and others. Radar systems of multifunctional aircraft. T.1. Radar - the information basis of the fighting of multifunctional aircraft. Systems and algorithms for primary processing of radar signals. / Ed. A.I. Kanaschenkova and V.I. Merkulova. - M .: Radio engineering, 2006.

4. Merkulov V.I., Kanaschenkov A.I., Chernov V.S., Drogalin V.V. and other Aviation systems of radio control. T.3. Command radio control systems. Autonomous and combined guidance systems. / Ed. A.I. Kanaschenkov and V.I. Merkulov. - M .: Radio engineering, 2004.

Claims (1)

The goniometric-correlation method for estimating the coordinates of the location of ground-based sources of radio emission (IRI), which consists in measuring the position coordinates x (k), the course angle ψ (k), the IRI bearing (φ _and (k)) simultaneously on the direction finding plane characterized in that the on-board computer system (BVS) splits the area around the IRI with roughly defined rectangular coordinates x _c , z _c into I × J rectangles with the coordinates of the centers x _i , z _i ; for each rectangle and all direction finding points, the expected values of bearings φ _ij (k) are calculated by the formula

where x (k), z (k) are the coordinates of the direction-finding aircraft at the k-th direction finding of the IRI,
x _i (k), z _j (k) - coordinates of the center of the partition rectangle,
ψ (k) is the direction-finding plane course at the k-th direction finding of the IRI;
then they search for an elementary locality of the possible location of the IRI, which corresponds to the set of measured values of bearings φ _and (k), determine the current location of the IRI by the value of the quality functional characterizing the degree of correspondence of the current measured set of bearings {φ _and (k)} and their expected calculated values {φ _ij (k)} corresponding to elementary terrain, the coordinates of which are known, while the extremum of the cross-correlation function is used as the quality functional implementation of φ _and (k) and φ _ij (k), which determines the coincidence of the current location of the IRI with the measured elementary area, the coordinates of which are known, or the weighted sum of the squares of the differences of the current measured and calculated values of bearings φ _and (k) and φ _ij (k) while the criterion for the coincidence of the current implementation of bearings and their calculated values is the minimum of the quality functional

where K is the number of direction finding points,
g (k) is the weight coefficient,
φ _and (k) - measurement of bearings IRI,
φ _ij (k) is the calculated value of the bearing,
then the determined coordinates of the IRI go to the consumer.

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