RU2619915C1 - Method for determining the source of radio emissions coordinate from the aircraft - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: method is based on measuring three orthogonal components of the electric field strength vector in the E_{ac x}, E_{ac y}, E_{ac z} spaces; forming of an auxiliary plane passing through the center by the airborne antenna system (AAS) of aircraft (AC) with coordinates (x_ac, y_ac, z_ac) and perpendicular to the electric field strength vector transformed into a topocentric coordinate system, which is determined by three orthogonal components E_{t x}, E_{t y}, E_{t z}; determining the RES position line as the intersection line of each of the auxiliary planes with the Earth's surface; and calculating the coordinates of radio emission sources (RES) at the point of intersection of the RES position lines formulated in process of AC movement.

EFFECT: increasing the accuracy of determining the coordinates of radio emission sources by providing polarization matching between the receiving airborne antenna system and the incoming electromagnetic wave field.

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Description

The invention relates to radio engineering and can be used in radio monitoring systems when solving the problem of covert determination of the coordinates of radio emission sources (IRI), in particular for determining the coordinates of the IRI from an aircraft.

A known method of determining the coordinates of the IRI according to patent RU No. 2510044 [1]. The method includes receiving signals in a given frequency band by a measuring instrument moving in space, measuring the primary coordinate-information parameters of the detected signals, which are used as the level of the evaluated signals, while measuring and storing secondary parameters: the coordinates of the meter’s location, repeatedly measuring the set of primary and secondary parameters in the process of moving the meter, sequentially calculating the relations of signal levels, building by subtraction to the interconnected relationships of the circular position lines and the determination of the coordinates of the IRI at the points of intersection of the circular position lines, for which the directions to the IRI are preliminarily determined using the goniometric-rangefinding method for determining the position (OMP) and the flight path of the aircraft is adjusted, then the rangefinding method of the OMP IRI is used. The known method allows to reduce the time spent on determining the coordinates of the IRI in conditions when restrictions are imposed on the overall dimensions of the direction-finding antenna.

The disadvantage of the analogue is the relatively low accuracy of determining the coordinates of the IRI.

            This is because when measuring the parameters of a radio signal, its polarization parameters are not taken into account, and to achieve acceptable accuracy in determining the coordinates, an additional adjustment of the flight path of the aircraft is required, which requires long-term electromagnetic contact with IRI.

There is also a method of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft according to the patent RU No. 2275746 [2]. The method includes receiving radio signals by an onboard antenna, frequency selection, bearing detection, registration and processing of the received data. The IRI coordinates are fixed as the intersection point of at least two bearing lines. The method allows for its implementation to combine the process of determining the coordinates of the IRI with other processes of radio monitoring: parametric and semantic control of signals.

The disadvantage of this analogue is the relatively low accuracy of determining the coordinates of the IRI.

This is primarily due to the occurrence of errors associated with random fluctuations in the spatial position of the direction-finding antenna plane during the flight of the aircraft. The magnitude of these errors is commensurate with the systematic and operational errors of the hardware used in the implementation.

The closest in technical essence to the claimed method of determining the coordinates of the IRI from the aircraft is the method of determining the coordinates of the IRI with amplitude-phase direction finding from the aircraft, described in patent RU No. 2432580 [3]. The method includes receiving radio signals by an airborne direction-finding antenna, frequency selection, determination of bearing lines, registration and weight processing of the received data. Bearing lines are determined in the direction-finding antenna plane, and according to the results of weight processing, auxiliary planes are formed, orthogonal to the direction-finding antenna plane and passing through each received bearing line. The position lines of the source of radio emissions are determined as the intersection lines of each auxiliary plane with the Earth's surface and calculate the coordinates of the IRI as the point of intersection of the IRI position lines.

With this method, the uncertainty associated with the lack of data on the elevation angle of the electromagnetic wave is eliminated, thereby reducing the number of errors in determining the coordinates of the IRI and increasing the accuracy of the readings.

The disadvantage of the closest analogue (prototype) is the relatively low accuracy of determining the coordinates of the IRI, since when measuring the parameters of a radio signal its polarization parameters are not taken into account, and there is a need to use antenna systems with spaced elements in space, which in most cases is impossible due to the limited dimensions of the aircraft.

The aim of the invention is to improve the accuracy of determining the coordinates of the IRI from the aircraft.

This goal is achieved by the fact that in the known method for determining the coordinates of the IRI from the aircraft, which consists in receiving radio signals by the on-board antenna system (BAS) with frequency selection, the coordinates of the IRI are calculated, for which the angle of orientation of the BAS in space is measured, then auxiliary planes are formed , measure the coordinates of the center of the UAS, determine the line of position of the IRI as the line of intersection of each of the auxiliary planes with the surface of the Earth and calculate the coordinates of the point of intersection of the line of position of the IRI, which when they are taken as IRI coordinates, and after receiving UAS radio signals with frequency selection, the orientation of the electric field vector of the received radio signals relative to the aircraft coordinate system is additionally measured. Then, after measuring the angle of orientation of the UAS in space, the measured orientation of the vector of the electric field strength of the received radio signals relative to the coordinate system of the aircraft is converted into a topocentric coordinate system. Moreover, auxiliary planes are formed after measuring the coordinates of the UAS center as planes perpendicular to the electric field vector of the received radio signals relative to the topocentric coordinate system and passing through the UAS center. The coordinates of the point of intersection of the position lines are calculated by the Gauss method or the Cramer method.

Thanks to the specified new set of essential features, the polarization between the receiving UAS and the field of the incoming electromagnetic wave is ensured when implementing the claimed method, which eliminates the occurrence of additional errors in determining the coordinates of the IRI and, therefore, indicates the possibility of increasing the accuracy of determining the coordinates of the IRI from the aircraft.

The claimed invention is illustrated by drawings, which show:

in FIG. 1 - coordinate systems geocentric, topocentric and aircraft;

in FIG. 2 - orientation angles of a solid in three-dimensional space;

in FIG. 3 - orientation of the electric field vector in three-dimensional space;

in FIG. 4 is a graphical representation of determining the position lines of the IRI;

in FIG. 5 - the effectiveness of the claimed method for determining the coordinates of the IRI from the aircraft.

The determination of the coordinates of the IRI is an important component of signal monitoring. The advantage of the IRI OMP system is stealth in determining coordinates due to the absence of active radiation. Placing the hardware of the WMD system on an aircraft, including unmanned aircraft [4], can significantly expand the monitoring zone with the ability to detect and determine the coordinates of Iran in hard-to-reach areas.

However, the use of aircraft as a platform for the deployment of radio monitoring means leads to a number of problems, the main of which are:

an increase in the level of interference and the associated reduction in the signal-to-noise ratio at the input of the on-board radio receiver (RPU);

limitation of weight and size indicators of the payload on the aircraft, which do not allow placing on it effective antenna systems and multi-channel RPU;

instability of the aircraft orientation in space, which leads to a sharp increase in direction finding errors and to a decrease in the accuracy of determining the coordinates of the IRI.

When determining the IRI coordinates from the aircraft, several coordinate systems are used, among which the geocentric coordinate system (SC), the topocentric SC and the aircraft SC, which are shown in FIG. one.

In the geocentric SC O _g X _g Y _g Z _g , the origin of O _g coordinates is aligned with the geometrical center of the Earth, the O _g X _g axis is at the intersection of the equatorial plane of the Earth and the plane of the initial meridian, the O _g Z _g axis is directed north, the O _g Y axis _r complements the coordinate system to the right.

In the topocentric SC O _t X _t Y _t Z _{t, the} beginning is aligned with the point of location of the observer on the Earth’s surface O _t , the axis O _t X _t is at the intersection of the plane of the local horizon and the plane of the observer’s meridian and is directed to the south, the axis O _t Z _{t is} directed along normal to the plane of the local horizon in the direction of removal from the center of the Earth O _g , the axis O _t Y _t complements the coordinate system to the right.

In the coordinate system of the aircraft, O _la X _la Y _la Z _{la the} beginning is aligned with the center of the onboard antenna, the axis O _la X _la lies in the horizontal plane, the axis O _la Z _{la is} directed upward, the axis O _la Y _{la is} directed along the earth's ground velocity vector.

The parameters of radio emission are measured in the SC LA O _la X _la Y _la Z _la , the center of which is connected with the center of the BAS LA, when constructing the auxiliary plane, calculating the position lines and determining the coordinates of the IRI, use the topocentric SC O _t X _t Y _t Z _t .

When determining the coordinates of the IRI, the orientation of the UAS with respect to the topocentric SC is taken into account. There are various methods for determining the orientation of a rigid body in three-dimensional space, each of which has its own advantages and disadvantages. The most common method for determining the orientation of a solid in three-dimensional space is the Euler angle method, according to which a solid can be moved from its initial position to any final position using three consecutive rotations around the Z, Y, X axes at the corresponding angles ξ _α , ξ _β , ξ _γ (Fig. 2).

The accuracy of determining the coordinates of the IRI from the aircraft is achieved due to the possibility of reducing the distance to the IRI, however, this reduction leads to the fact that the reception of radio signals from the IRI is carried out in the interval of the elevation angle β = 45 ... 90 °, which leads to a decrease in the coordination coefficient for polarization between the receiving ALS and the field of the incoming electromagnetic wave. A decrease in the polarization matching coefficient leads to a decrease in the accuracy of determining the coordinates of the IRI from the aircraft.

The radio signal arriving at the BAS input carries information about the spatial position of the IRI contained in the values of certain parameters: amplitude, frequency, phase, delay time, arrival angles, and polarization parameters of the radio wave.

в пространстве необходимо определить три ортогональные составляющие вектора напряженности в системе координат ЛА О_лаX_лаY_лаZ_ла [5].Taking into account the polarization parameters of the radio wave is possible by measuring the spatial position of the electric field vector in space. To determine the orientation of the electric field vector

in space, it is necessary to determine the three orthogonal components of the tension vector in the coordinate system LA O _la X _la Y _la Z _la [5].

определяется с помощью триортогональной антенной системы, в которой измеряются три составляющие вектора напряженности электрического поля Е_{ла x}, Е_{ла y}, Е_{ла z} [6, 7] (фиг. 3).Spatial orientation of the electric field intensity vector on board the aircraft

is determined using a triorthogonal antenna system in which three components of the electric field vector E _{la x} , E _{la y} , E _{la z} are measured [6, 7] (Fig. 3).

на три матрицы поворота А₃(ξ_α), A₂(ξ_β), A₃(ξ_γ), соответствующие углам Эйлера ξ_α, ξ_β, ξ_γ [8]:The electric field vector is converted into a topocentric coordinate system due to the successive multiplication of the measured vector

into three rotation matrices A ₃ (ξ _α ), A ₂ (ξ _β ), A ₃ (ξ _γ ) corresponding to Euler angles ξ _α , ξ _β , ξ _γ [8]:

,

,

Where

,

,

.

,

,

.

The auxiliary plane passing through the center of O _la BAS LA with coordinates (x _la , y _la , z _la ) and perpendicular to the electric field vector in a topocentric coordinate system, which is determined by three orthogonal components Е _{t x} , Е _{t y} , E _{t z} , can be described by the equation [8]:

Ax + By + Cz + D = 0,

where A = E _{t x} ; B = E _{t y} ; C = E _{t z} ; D = -E _{t x} x _la -E _{t y} y _la -E _nz z _la .

The Iranian position line is found when solving a system of linear equations:

,

,

where z = f (x, y) is the equation of the Earth's surface.

If the Earth's surface is defined by a plane, then the solution of the given system of linear equations is the expression for the line of position of the IRI Ax + By + D = 0 with the measured coefficients A, B and D.

The coordinates of the IRI M (x _and ; y _and ; z _and ) are defined as the coordinates of the intersection point of two or more position lines (Fig. 4). During the flight of an aircraft, repeated measurements of the coefficients A, B, and D of the IRI position line are made Ax + By + D = 0, the construction of the position lines and the determination of the IRI coordinates at the points of intersection of the position lines is possible using one of the known methods, for example, solving the system of equations using the Cramer method , matrix method or Gauss method [8].

To test the feasibility of achieving the formulated technical result, computer simulation was carried out.

The method for checking the accuracy of determining the coordinates of the IRI from the aircraft was as follows.

The initial data is randomly polarized radio emission at the input of the BAS of the aircraft for various signal parameters and the relative positions of the aircraft and the IRI, which was formed using a program for modeling randomly polarized radio waves based on the mathematical apparatus of quaternions [9].

The calculation of the coordinates of the IRI and the estimation of the accuracy of determining the coordinates were performed by the claimed method and the prototype method.

A comparative analysis of the results showed that, with a range of IRI of D = 30 km and a direction finding error of σ _θ = 3 °, the prototype method provides an OMR of IRI with a standard deviation radius R _sk = 2.8 km, and the claimed method with R _sk = 1, 7 km. With a range to the IRI D = 35 km and a direction finding error of σ _θ = 1 °, the prototype method provides an OMR IRI with R _ck = 2.5 km, and the claimed method R _ck = 1.25 km.

Thus, the proposed method improves the accuracy of determining the coordinates of the IRI from the aircraft. When conducting computer simulation, the accuracy of determining the coordinates of the IRI increased from 30 to 50%, depending on the flight conditions of the aircraft and the parameters of radio emission (Fig. 5).

INFORMATION SOURCES

1. Patent 2510044 (Russia). Method and device for determining the coordinates of radio emission sources / V.A. Zarenkov, D.V. Zarenkov, B.I. Dikarev, A.S. Danilyuk. - 2006.

2. Patent 2275746 (Russia). Radio intelligence station / C.M. Vishnyakov, M.V. Kulikov, A.G. Mityanin, P.L. Smirnov, D.V. Tsarik, O.V. Tsarik, A.M. Shepilov, A.Ya. Bumps. - 2012.

3. Patent 2432580 (Russia). A method for determining the coordinates of a source of radio emissions during amplitude-phase direction finding from an aircraft / A.V. Wassenkov, O.B. Guzenko, A.S. Dikarev, V.A. Skobelkin. - 2011.

4. Moses B.C. Russian unmanned aircraft: the main problems and solutions. Materials of the All-Russian Scientific and Technical Conference "X Scientific Readings on the Memory of N.E. Zhukovsky ”/ Collection of reports. - M.: Publishing House of the Academy. NOT. Zhukovsky, 2013 .-- S. 554-559.

5. Kanareikin DB, Pavlov NF, Potekhin V.A. Polarization of radar signals. - M .: "Soviet Radio", 1966. - 440 p.

6. Patent 2268520 (Russia). Antenna / S.V. Zemlyansky, E.N. Mishchenko, S.E. Mishchenko, V.V. Shatsky. - 2006.

7. Komarovich V.F., Nikitchenko V.V. Methods of spatial processing of radio signals. - L .: YOU, 1989 .-- 278 p.

8. Korn G., Korn T. Handbook of mathematics for scientists and engineers. - M .: Nauka, 1973. - 832 p.

9. Bogdanovsky S.V., Simonov A.N., Teslevich S.F., Medvedev M.V. A program for modeling randomly polarized radio emission based on the mathematical apparatus of quaternions. Certificate of state registration of computer programs in FIPS (Rospatent) No. 2015661417 dated 10.22.2015. Bull. No. 11.

Claims (2)

1. The method of determining the coordinates of the source of radio emissions (IRI) from the aircraft (LA), which consists in the fact that they receive radio signals by the onboard antenna system (BAS) with frequency selection, calculate the coordinates of the IRI, which measure the orientation angles of the BAS in space, then form auxiliary planes, measure the coordinates of the center of the UAS, determine the line of position of the IRI as the intersection of each of the auxiliary planes with the Earth’s surface, and calculate the coordinates of the point of intersection of the line of position of the IRI, which they are taken as IRI coordinates, characterized in that after receiving the UAS radio signals with frequency selection, the orientation of the electric field vector of the received radio signals relative to the aircraft coordinate system is additionally measured, and after measuring the angles of the UAS orientation in space, the measured orientation of the electric field vector of the received radio signals relative to the system is converted coordinates of the aircraft in a topocentric coordinate system, with auxiliary planes being formed after measuring the coordinate inat of the UAS center as planes perpendicular to the electric field vector of the received radio signals relative to the topocentric coordinate system and passing through the UAS center. 2. The method according to p. 1, characterized in that the coordinates of the intersection point of the position lines are calculated by the Gauss method or the Cramer method.

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