RU2840399C2 - Method of determining type of closed trajectory of movement of radio-frequency sources - Google Patents

Abstract

FIELD: radar.

SUBSTANCE: invention relates to passive radar and can be used to determine the type of closed trajectory of a radio-frequency source (RFS). In the disclosed method, over a certain period of time, the memory of the radio control apparatus accumulates values of change in Doppler frequency shifts, the analysis of which enables to determine the type of the closed trajectory of the RFS.

EFFECT: determining the type of the trajectory of the RFS based on an estimate of the change in Doppler frequency shifts of the RFS for a certain period of time.

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Description

Field of technology to which the invention relates

The invention relates to the field of passive radar and can be used to determine the type of closed trajectory of movement of a radio emission source (RES) using radio engineering means.

State of the art

A method for determining the radial velocity of movement of a moving radio-electronic source with unknown parameters and a device for implementing it are known [Russia, patent No. 2211460 G01S 13/58, 11/10, 2003], based on the use of the Doppler effect, reception, selection and processing of received radio emission, its comparison in frequency with the reference and calculation of the radial velocity value based on the found frequency difference, reception and selection of the direct emission signal is carried out by a quasi-two-channel receiving device, in which one channel is real and the second channel is virtual, wherein the receiving antenna of the virtual channel "moves" relative to the real antenna with a radial velocity V _ga , and the real measuring operations in the virtual channel are replaced by calculation operations carried out taking into account the Doppler effect.

This method provides measurement of the speed of movement of the RES, but does not involve accumulation of the Doppler frequency over a certain period of time, due to which it is impossible to determine the type of trajectory of movement of the RES.

The closest in technical essence to the proposed method is the method for measuring the course angle of movement of a source of probing signals [Russia, patent No. 2545068, G01S 3/80, 2015], based on the fact that the determination of the change in the course angle of movement of a target relative to a stationary hydroacoustic receiver is carried out based on the accumulated received signals.

The disadvantage of this method is that the calculations of the change in the object's speed and course angle are introduced at the moments of signal reception, resulting in significant measurement errors, and as a consequence, it is impossible to accurately determine the trajectory of the object's movement.

The purpose of the invention is to provide the ability to determine the type of closed trajectory of the movement of the RES over a certain period of time based on an analysis of the change in the Doppler frequency shifts of the RES.

Disclosure of invention

The technical result of the invention is the determination of the type of closed trajectory of the IRI movement by analyzing changes in the Doppler frequency shifts of the IRI over a certain period of time.

The essence of the method is that, based on the analysis of changes in the signal parameter (Doppler frequency shift), the operator determines the type of closed trajectory of the movement of the radio-electronic equipment in conditions of incomplete information about the type of the control object and the conduct of radio-technical control from one position.

The technical result is achieved by analyzing the accumulated values of Doppler frequency shifts in the storage device of the radio control device.

The technical result of this technical solution is manifested in the following possibilities:

- assessment of the type of trajectory of the IRI and measurement of the main parameters of the IRI;

- single-position measurement of the trajectory type of the IRI.

The proposed method for determining the trajectory of the IRI movement is as follows.

The storage device of the radiotechnical control facility accumulates the parameters of the received signals for a certain period of time. The operator of the radiotechnical control facility analyzes the changes in the values of the Doppler frequency shifts, which allows him to determine the type of closed trajectory of the IEE movement.

Let us consider the case of the movement of the IEE along a circular trajectory. Fig. 1 shows the movement of the IEE along a circular trajectory.

The Doppler shift of the radio signal frequency is determined by the well-known expression [Kologrivov V.N. The Doppler Effect in Classical Physics. Moscow: Moscow Institute of Physics and Technology. 2012]:

where λ is the wavelength of radio emission, V _r is the radial component of the velocity vector of the radio emission.

Let us limit ourselves to a fairly common case, when the range to the IRI (D) is much greater than the diameter of the trajectory (R), i.e. D>>R, then, taking into account the property of the tangent to the circle, the angle in can be determined as:

where α is the angle of rotation of the RES at the current moment of time along a circular trajectory, relative to a pre-selected reference point. Then the Doppler shift of the RES frequency will be determined by the following expression:

If we assume that the frequency of the IRI does not change during the flight and the speed changes slightly during the flight, then we can designate Then

Thus, in the case of the RES moving along a circular trajectory, the Doppler shift of the RES frequency is modulated by the multiplier sin(α). The time spent by the RES to fly along a circular trajectory can be determined using the periodicity property of the multiplier sin(α).

Fig. 2 shows a schematic view of the graphical display of the derived dependence of the Doppler shift of the IRI frequency when moving along a circular trajectory.

The period ΔT _rev. , determined by the periodicity of the sin(α) multiplier in the law of change of the Doppler shift of the IRI frequency, is the time that the IRI spends on flying along a circular trajectory.

Thus, it is possible to draw a conclusion about the type of trajectory and estimate the time and geometric parameters of the motion based on the assessment of the change in the Doppler shift of the IEE frequency. The method for analyzing the change in the Doppler shift of the IEE frequency may consist of a correlation comparison of the distribution of measured values of the Doppler additive with templates - specially formed distributions of values modulated by sin(α), with different time parameters.

Next, we will consider the case of the IRI movement along a trajectory that has an elliptical shape, while the trajectory is not strictly an ellipse, but for brevity we will call this trajectory elliptical. Fig. 3 shows the movement of the IRI along an elliptical trajectory.

We will name the sections of the trajectory A - B and D - C - extended sections of the elliptical trajectory (extended sections), the determining geometric parameters are the length - d and the angle θ - the angle between the main axis of the elliptical trajectory and the line connecting the RTK vehicle and the geometric center (O). We will name the sections B-C and A-D - circular sections of the elliptical trajectory (circular sections), the determining geometric parameter is R - the radius of curvature of the trajectory on this section.

Let us limit ourselves to a frequently encountered case, when the range to the IRI is much greater than the length of the extended sections of the trajectory and the radius of curvature on the circular section, i.e. D>>d, R.

Let us consider the change in the Doppler frequency shift of the RES moving along extended sections of the trajectory. Under the condition D>>d, the angle defining the radial component of the RES velocity relative to the control means will be equal to the angle θ - the angle between the main axis of the elliptical trajectory and the line connecting the control means and the geometric center (O), then the Doppler frequency shift of the RES will have a constant value in these sections and will be determined by the following expression:

Let us consider the change in the Doppler frequency shift of an ionizing radiation source moving along circular sections of its trajectory.

The value of the Doppler frequency shift will be determined by the dependencies that were considered earlier, namely:

where the angle α takes values determined by the spatial location of the trajectory, from to

In total, the model of the change in the Doppler frequency shift when the IRI moves along an elliptical trajectory looks like this:

Fig. 4 shows a schematic view of the reduced dependence of the Doppler shift of the IRI frequency.

The value of T _d determines the duration of the movement of the RES along an extended section, the value of T _R determines the duration of the movement along a circular section of the trajectory, the angle θ, which characterizes the relative position of the elliptical trajectory and the control means, can be determined with an accuracy of up to a module as follows:

Thus, based on the obtained model of the change in the Doppler shift of the IRI frequency in the case of movement along an elliptical trajectory, it is possible to estimate the time and geometric parameters of the elliptical trajectory of the IRI movement.

Comparing the proposed method with the prototype and analogues, as well as the results of searching for known technical solutions in this and related fields of technology in order to identify features that coincide with the distinctive features of the claimed method, it was shown that they are absent from publicly available sources of information. Consequently, the claimed invention meets the criterion of "novelty" and "inventive step".

The presence of the corresponding element base, on the basis of which devices can be made that implement this method with the achievement of the specified result, determines the “Industrial applicability” of this method.

The proposed method, based on the assessment of the change in the Doppler frequency shift of the RES, allows determining the type of trajectory, time and geometric parameters of the RES movement.

Claims (1)

A method for determining the type of a closed trajectory of movement of radio emission sources by a radio engineering means, which consists in the fact that the type of a closed trajectory is determined on the basis of reception, accumulation of radio signals of radio emission sources with a Doppler frequency additive and analysis of the accumulated values of the Doppler frequency additive of radio emission sources, characterized in that signals of radio emission sources (RES) are received by a single-position radio engineering monitoring means, radio signals of the RES with values of Doppler frequency shifts are accumulated over a certain period of time in a storage device of the radio engineering monitoring means, an analysis of the change in the Doppler frequency shift of the RES is carried out, which consists in a correlation comparison of the distribution of measured values of the Doppler additive with templates that are pre-formed distributions of the values of the Doppler frequency additive, modulated by sin(α), where α is the angle of rotation of the RES at the current moment in time along a circular trajectory of movement of the RES relative to a pre-selected reference point, or modulated by cos(θ), where θ is the angle between the main axis elliptical trajectory and the line connecting the radiotechnical monitoring facility and the geometric center of the elliptical trajectory of the radio emission source, based on the results of the correlation comparison, the type of closed trajectory of the radio emission sources is determined, based on the obtained model of the change in the Doppler frequency shift of the radio emission source in the case of movement along a circular or elliptical trajectory and taking into account the accumulated values of the Doppler frequency shift of the radio emission source, the temporal and geometric parameters of the circular trajectory of the radio emission source are estimated: the period of flight of the radio emission source along a circular trajectory, the radius of curvature of the circular trajectory of the radio emission source, or the temporal and geometric parameters of the elliptical trajectory of the radio emission source: the duration of movement of the radio emission source along an extended section of an elliptical trajectory, the duration of movement of the radio emission source along a circular section of an elliptical trajectory, the radius of curvature of the elliptical trajectory of the radio emission source, the length of the extended section of the elliptical trajectory of the radio emission source.