RU2432580C1 - Method to determine coordinates of radio-wave radiation source in process of amplitude-phase direction finding on board of aircraft - Google Patents

Abstract

FIELD: radio engineering. ^ SUBSTANCE: invention may be used to determine coordinates of radio-wave radiation sources (RWRS), in particular, to determine RWRS coordinates in process of amplitude-phase direction finding on board of an aircraft (AC). The method to determine RWRS coordinates in process of amplitude-phase direction finding on board of the AC, including reception of radio signals by an onboard finding antenna, a frequency selection, detection of bearing lines, registration and weight processing of produced data, additionally includes operations of auxiliary planes formation, which are orthogonal to the plane of the finding antenna and passing through each produced bearing line, detection of RWRS position lines as crossing of each auxiliary plane with the Earth surface and calculation of RWRS coordinates as the point of crossing of RWRS position lines, and detection of bearing lines is carried out in the finding antenna plane. ^ EFFECT: increased accuracy of radio-wave radiation source coordinates detection. ^ 4 dwg

Description

The invention relates to radio engineering and can be used to determine the coordinates of radio emission sources (IRI), in particular to determine the coordinates of the IRI during amplitude-phase direction finding from an aircraft (LA).

The determination of the coordinates of the IRI is an important component of signal monitoring. The advantage of direction finding in the positioning system (MO) of IRI is secrecy in determining coordinates due to the absence of active radiation. The placement of direction finding means on an aircraft, including unmanned aircraft [1], can significantly expand the monitoring zone and carry out preventive detection and determination of coordinates of IRI.

A known method for determining the coordinates of the IRI, based on the direction finding process described in patent RU No. 2192651 [2]. The method includes receiving a signal by elements of a linear equidistant antenna array (LEAR), additionally receiving this signal by elements of a second LEAR located perpendicular to the first LEAR, and non-linear signal processing, during which the complex conjugate spatial Fourier spectrum of the direction-finding signal received by the elements of the first and second LEAR, convert the scales of both calculated spatial spectra according to the logarithmic law, produce a correlation analysis and measure relative nth shift of the transformed spatial spectra and estimate the angular coordinate of the signal source in accordance with the expression θ = arctan (expΔ), where Δ is the measured relative shift of the transformed spatial spectra of the direction-finding signal. IRI coordinates are determined by two or three bearings received. The known method allows for the possibility of direction finding of the source of any a priori unknown signal.

However, the accuracy of determining the coordinates of the IRI when using the known method by airborne aircraft is low. This is due to the fact that there is an error in determining the coordinates associated with random fluctuations in the spatial position of the plane of the direction-finding antenna during the flight of the aircraft, and the magnitude of this error is commensurate with the systematic and operational errors of the direction finder itself. The disadvantage of this method is that its narrow functional orientation does not allow to combine the process of determining the IRI with other processes of radio monitoring. Two LEARs required for the implementation of the method are quite complicated when installed on an aircraft, especially on a small unmanned aircraft.

A known method of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft, used by the device according to patent RU No. 2275746 [3]. 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.

But the accuracy of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft in a known manner is low. 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 object is a method for determining the coordinates of the IRI with amplitude-phase direction finding from the aircraft, described in [4, p.18-22] (prototype). The method includes receiving radio signals by an onboard antenna, frequency selection, determination of bearing lines, registration and weight processing of the received data. The IRI coordinates are fixed as the intersection point of at least two bearing lines. Bearings on the IRI are measured during the flight sequentially as they approach the traverse line and further move away from it. Carrying out the weight processing of the results of direction finding allows to reduce errors in fixing the coordinates of the IRI and thereby improve accuracy.

However, the accuracy of determining the coordinates of the IRI when using the known method is insufficient. This is explained by the occurrence of errors caused by random fluctuations in the spatial position of the direction-finding antenna plane during the flight of the aircraft.

The aim of the invention is to increase the accuracy of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft.

This goal is achieved due to the fact that in the known method of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft, including the reception of radio signals by the direction-finding antenna, frequency selection, determination of bearing lines, registration and weight processing of the received data, the operations of determining the lines of bearings are introduced direction-finding antenna planes, formation of auxiliary planes orthogonal to the direction-finding antenna plane and passing through each received bearing line, line definitions the position of the IRI as the intersection of each auxiliary plane with the Earth's surface and the calculation of the coordinates of the IRI as the point of intersection of the lines of position of the IRI.

The introduction of new operations in the known method for determining the coordinates of the IRI allows you to eliminate the uncertainty associated with the lack of data on the angle of the place of arrival of the wave, thereby reducing the number of errors in determining the coordinates of the IRI and increasing the accuracy of readings.

The combination of distinctive features and properties of the proposed method for determining the coordinates of the IRI during amplitude-phase direction finding from the aircraft from patent sources are not known, therefore it meets the criteria of novelty and inventive step.

Figure 1 shows a functional diagram of a device for determining the coordinates of Iran, which implements the proposed method;

figure 2 - coordinate system for direction finding;

figure 3 - the process of constructing a line of position of the IRI;

figure 4 - algorithm for determining the coordinates of the IRI.

The IRI coordinate determination device (Fig. 1) that implements the proposed method comprises a direction-finding antenna 1, a receiver 2, a navigation antenna 3, a satellite navigator 4, a bearing calculation module 5, a weight processing module 6, a position line determination module 7, an IRI coordinate calculator 8 , a mapping and display module 9 and a software control module 10. The receiver 2 includes a series-connected mixer 11, the input of which is connected to the signal output of the direction-finding antenna 1, and the signal from the output of the local oscillator 12, the first band-pass filter 13, the intermediate-frequency amplifier 14, the first multiplier 15, the narrow-band filter 16 and a phase detector 17, the output of which is connected to the second input of the bearing calculation module 5, whereby a signal from the output of the reference generator 18 is supplied to the second input of the first multiplier 15 through the second multiplier 19 and the second strip liter 20, the output of the intermediate frequency amplifier 14 through the delay line 21 is connected to the second input of the second multiplier 19, the output of the reference generator 18 is connected to the second input of the phase detector 17. Bearing calculation module 5 through weight processing module 6, IRI position line determination module 7, and calculator 8 coordinates of the IRI is connected to the mapping and display module 9, the first input of the bearing calculation module 5, the third input of which receives a signal from the output of the navigation antenna 3 through the satellite navigator 4, and the second input to the mode To determine the position lines of the IRI 7, they are connected to the second output of the direction-finding antenna 1, the first output of the software control module 10 is connected to the control inputs of the satellite navigator 4, the bearing calculation module 5, the weight processing module 6, the IRI position determination module 7, and the calculator 8 through the control bus IRI coordinates, the second input of which is connected to the second output of the local oscillator 12, and the second output of the program control module 10 is connected to the control input of the local oscillator 12. The output of the mapping and display module 9 S THE IRI coordinate output determination unit.

The method of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft is implemented as follows.

на плоскость X0Y и соответственно

на плоскость X₁0Y₁. Ошибка ориентации может быть вычислена как разница углов ∠X0P' и

:When determining the coordinates of the IRS from the aircraft, an error occurs associated with random fluctuations in the spatial position of the plane of the direction-finding antenna during flight. The determination of the coordinates of the aircraft using analogues is carried out in the coordinate system associated with the aircraft, and the problem of locating the IRI is solved in the local coordinate system, the origin of which is connected with the Earth. It is impossible to ensure with a sufficient degree of accuracy the initial orientation of the aircraft coordinate system with the local coordinate system associated with the Earth, since the coordinates and orientation angles of the aircraft (heading, roll, pitch) are continuously changing during the flight. In this regard, the true bearing on the IRI will differ from that measured by the value of the orientation error Δθ. Figure 2 shows two Cartesian rectangular coordinate systems: the 0XYZ system parallel to the local coordinate system (in which bearings are laid down and the IRI location problem is solved), its center is connected to the center of the direction-finding antenna of the aircraft, and the coordinate system is 0X ₁ Y ₁ Z ₁ , center which coincides with the coordinate center 0XYZ, the axis 0X _{1 is} parallel to the aircraft construction axis, and the plane X ₁ 0Y ₁ coincides with the plane of the direction-finding antenna. A vector 0P was introduced, the beginning of which coincides with the center of the direction-finding antenna, and the end lies at the spatial location of the direction-finding IRI. The vector 0P in the coordinate system XYZ is described by a triple of numbers x _p , y _p , z _p , and in the coordinate system X ₁ Y ₁ Z ₁ - x1 _p , y1 _p , z1 _p . 0P beam has a projection

to the plane X0Y and, accordingly,

to the plane X ₁ 0Y ₁ . Orientation error can be calculated as the difference of the angles ∠X0P 'and

:

The position of the coordinate system 0X ₁ Y ₁ Z ₁ relative to the coordinate system 0XYZ is determined by the corresponding guide cosines of the axes:

axis 0X ₁ t ₁₁ = cos (∠x ₁ 0X), t ₂₁ = cos (∠x ₁ 0Y), t ₃₁ = cos (∠x ₁ 0Z);

axis 0Y ₁ t _l2 = cos (∠y ₁ 0X), t ₂₂ = cos (∠y ₁ 0Y), t ₃₂ = cos (∠y ₁ 0Z);

axis 0Z ₁ t ₁₃ = cos (∠z ₁ 0X), t ₂₃ = cos (∠z ₁ 0Y), t ₃₃ = cos (∠z ₁ 0Z).

If the vector 0P is unit, then for the coordinate system 0XYZ we can represent:

where φ is the azimuth of the arrival of the wave, β is the angle of the place of arrival of the wave.

In this case, for the coordinate system 0X ₁ Y ₁ Z ₁ :

The direction cosines are associated with the values of the course angles - ψ, roll - γ and pitch υ LA relations:

The final expression for the orientation error is obtained by successively replacing the variables in the above expressions (4), (3), (2) and (1). Thus, the magnitude of the orientation error is a nonlinear function of five variables

,

,

where ψ, γ, υ - current angles of the course, roll and pitch of the aircraft;

φ, β - azimuth and elevation angle of the wave arrival at the point of location of the aircraft.

Errors caused by fluctuations in heading, roll and pitch angles are largely systematic, depend on the type and design of the aircraft and are measurable and predictable. It follows that the exception from the direction finding process of determining the angle of wave arrival at the aircraft location point will significantly reduce the errors in determining the coordinates of the IRI during amplitude-phase direction finding from the aircraft.

To calculate the coordinates of the IRI, lines of bearings are used, which are understood as the projections of the straight lines connecting the aircraft (the center of the direction-finding antenna) with the IRI, on the corresponding plane. In analogs and in the prototype, projection onto the plane (surface) of the Earth was used. To minimize the errors in obtaining the coordinates of the IRI by the proposed method, the determination of the bearing lines is carried out in the plane of the direction-finding antenna, and the operations of forming auxiliary planes orthogonal to the plane of the direction-finding antenna and passing through each received line of the bearing are introduced, determining the position lines of the IRI as the intersections of each auxiliary plane with the Earth’s surface and calculating the coordinates of Iran as the point of intersection of the lines of position of the Iran. Figure 3 graphically shows the construction of the line of position of the IRI.

The auxiliary plane orthogonal to the direction-finding antenna plane and passing through the bearing line is described by the equation

whose coefficients are found through the formulas for the equation of a plane passing through three known points P ₁ (x ₁ , y ₁ , z ₁ ), P ₂ (x ₂ , y ₂ , z ₂ ), P ₃ (x ₃ , y ₃ , z ₃ ):

Known points are selected with coordinates in the coordinate system associated with the aircraft.

The coordinates of the selected points in the local coordinate system associated with the Earth are based on a priori knowledge of the values of the orientation angles of the aircraft’s own coordinates:

The coefficients for controlling the auxiliary plane are found by substituting the obtained coordinates of the selected points.

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

where the second equation describes the surface of the earth.

If the Earth’s surface is a plane, then the solution of the given system of linear equations is the expression for the line of position of the IRI

with known coefficients A, B and D.

The block diagram of the algorithm illustrating the method for determining the coordinates of the IRI is shown in Fig.4.

Thus, the angle β of the place of arrival of the wave at the point of location of the aircraft is absent. Reducing the number of factors affecting the value of Δθ, improves the accuracy of determining the coordinates of the IRI.

The whole cycle of determining the coordinates of the IRI of the proposed method can be implemented using a device for determining the coordinates of the IRI, a functional diagram of which is shown in figure 1. The signal f _c IRI is fed to the direction-finding antenna 1 and then to the receiver 2. In the receiver 2, the signal is converted in the mixer 11 to an intermediate frequency using a local oscillator 12 with a frequency f _Г.

The intermediate frequency f _{IF 1} corresponds to the formula f _G = f _c ± f _{IF 1} . The intermediate frequency signal is fed through the first band-pass filter 13 and the intermediate-frequency amplifier 14 to the input of the first multiplier 15 and through the delay line 21 to the input of the second multiplier 19. The passband of the first band-pass filter 13 is selected close to the spectral width of the IRI signal: Δf _PF1 = Δf _c . The second multiplier 19 transfers the intermediate frequency to the value f _PR = f _IF1 + f _OG , where f _OG is the frequency of the reference oscillator 18 supplied to the other input of the second multiplier 19. The output signal of the second multiplier is filtered by the second bandpass filter 20, the passband of which Δf _PF2 = Δf _PF1 = Δf _c . The signal at the middle frequency f _PR from the output of the second band-pass filter 20 is fed to the second input of the first multiplier 15, as a result, the signal at the output of the first multiplier 15 has a frequency f _{IF 2} = f _PR -f _IF 1 = f _OG . Devices 15, 18-21 provide autocorrelation convolution of the signal spectrum to frequency f _ПЧ2 , the stability of which is completely determined by the stability of the reference oscillator 18. The passband of the subsequent narrow-band filter 16 depends only on the permissible inertia of the receiver 2.

The frequency signal f _{IF 2} is supplied to the phase detector 17, the reference voltage to which is supplied from the output of the reference generator 18. The response of the phase detector 17 is supplied to the second input of the bearing calculation module 5.

The determination of bearings during an aircraft flight is performed repeatedly by module 5. To find the coordinates of the IRI, two bearings are sufficient. But the error in determining the coordinates depends on the standard error of the individual bearings [4, p.12]:

,

,

where R1 and R2 - the distance between the location of the aircraft and Iran;

σ a 1 and σ a 2 - standard errors of direction finding;

γ is the angle between two bearings.

It follows that to reduce the measurement error of the coordinates of the IRI, it is necessary to reasonably choose a pair of bearings obtained.

The solution to this problem is provided by the module 6 weight processing, which serves encoded bearings from the output of module 5.

Module 6, when processing bearings, uses weights:

,

,

,

,

where n is the number of independent pairs of bearings;

,

- средневзвешенные оценки координат ИРИ;

,

- weighted average estimates of the coordinates of the IRI;

x _i , y _i - coordinates of the intersection point of the i-th pair of bearings;

p _xi , p _yi are the weighting coefficients of the ith pair of bearings, which, in order to obtain minimum errors, must be selected inversely with the variances D _x , D _{y of} each measurement [4, p.19]

,

,

where a _i , a _j - heading angles;

Ri = D / sin a _i , R _j = D / sin a _j .

An encoded pair of bearing values from the output of the module 6 for weighing is fed to the information input of the module 7 for determining the position of the IRI, the operation of which is carried out in accordance with the above formulas (9), according to which operations are carried out to determine the auxiliary planes orthogonal to the plane of the direction-finding antenna and passing through each received bearing line, and determining the position lines of the IRI as the intersection of each auxiliary plane with the Earth's surface (formula (10)).

The output signals of the module 7 determining the position lines of the IRI are fed to the calculator 8 coordinates of the IRI and then to the module 9 mapping and display.

The algorithm of the device direction finding IRI (figure 1) is as follows:

- the launch is carried out by the command of the module 10 software control;

- from the output 2 of the module 10, a signal is supplied to the control input of the local oscillator 12, providing tuning to the average frequency of the IRI signal;

- from the output 1 of module 10, control signals are sent to the satellite navigator 4, which determines the coordinates of the aircraft, as well as the angles of the course, roll and pitch, and modules 5-8 of the direction finding device;

- module 5 calculates the bearings on the IRI using the position signal of the direction-finding antenna 1 as input to the input 1 of module 5, the signal from the output of the phase detector 17 and the signals of the satellite navigator 4. The results in the form of encoded values of the bearings are fed to the weight processing module 6 ;

- module 6 weight processing selects a pair of bearing lines corresponding to the minimum error of measurements. The processing results are fed to module 7;

- module 7 determines the line of position of the IRI, using as reference signals of the module 6 weight processing and the position signal of the direction-finding antenna 1. The results are fed to the calculator 8 coordinates of the IRI;

- the calculator 8 determines the coordinates, simultaneously registering the frequency of the IRI by the local oscillator signal 12 taking into account the shift by the value of the intermediate frequency, and supplies the output data to the module 9, which provides mapping, indication and recording of the results of determining the IRI.

The device does not require information on the angle of the place of arrival of the wave of the IRI signal to determine the coordinates of the IRI.

All nodes of the receiver 2 can be performed similarly to the corresponding nodes of the receiver according to patent RU No. 2275746.

Modules 5-7 and calculator 8 coordinates of IRI can be performed, for example, on the basis of processors Texas Instruments TMS 320 C 6416/6713 and FPGA [5].

As a satellite navigator 4 can be used, for example, the device MRK 11 [6].

Thus, the proposed method can significantly improve the accuracy of determining the coordinates of the IRI during the amplitude-phase direction finding from the aircraft. When tested in real conditions, the accuracy of determining the coordinates of the IRI increased from 20 to 60%, depending on the flight conditions of the aircraft. An experimental verification of the proposed method confirmed the correctness and sufficiency of technical solutions.

INFORMATION SOURCES

1. Vasilin N.Ya. Unmanned aerial vehicles. - Mn .: OOO "Potpourri", 2003.

2. The method of direction finding of the signal source. Patent RU No. 2192651, IPC G01S 3/00, 3/14, publ. 11/10/2002, bull. No. 31.

3. Radio intelligence station. Patent RU No. 2275746, IPC G01S 7/28, 13/32, publ. 04/27/2006.

4. Melnikov Yu.P., Popov S.V. Radio intelligence. Methods for assessing the effectiveness of the determination of radiation sources. - M.: Radio Engineering, 2008.

5. Potekhin D.S., Tarasov I.E. Development of FPGA-based digital signal processing systems. - M .: Hot line - Telecom, 2007.

6. Equipment MRK-11. Manual. UE2.517.006 RE. Research Institute of Radio Engineering KSTU. - Krasnoyarsk, 2004.

Claims (1)

A method for determining the coordinates of a radio emission source during amplitude-phase direction finding from an aircraft, including receiving radio signals from an aircraft direction-finding antenna, frequency selection, determination of direction-finding lines, recording and weighting of the received data, characterized in that the direction-finding lines are determined in the direction-finding antenna plane, and The results of weight processing form auxiliary planes orthogonal to the direction-finding antenna plane and passing through each received bearing line , determine the position lines of the source of radio emissions as the intersection lines of each auxiliary plane with the Earth's surface, and calculate the coordinates of the source of radio emissions as the point of intersection of the lines of position of the source of radio emissions.

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