Two-position System Research Articles

Trajectory control of observation. Part 4. Control of a two-position system providing semi-active synthesis of the aperture

Trajectory control of observation. Part 4. Control of a two-position system providing semi-active synthesis of the aperture

Способы отождествления пеленгов в двухпозиционных угломерных системах радиомониторинга воздушного базирования.

For aeronautical goniometric systems for radio monitoring of radio emission sources (RES), one of the primary tasks is the identification of bearings. It is especially difficult to solve the problem of identifying bearings if there are several RESs in the observation area in the case when they are located in the same plane with the direction finders. In this case, the problem of identifying bearings in goniometric two-position systems is solved in the process of performing a two-stage procedure. At the first stage, the primary identification of single measurements of bearings is carried out separately at each receiving position (RP) when receiving radio signals from the RES, and at the second stage, the secondary (inter-positional) identification of bearings arriving from both RPs is carried out. In the initial identification, strobe and strobeless identification algorithms are used. In the secondary identification for selection of true and false points of intersection of bearings on the plane, it is proposed to use the kinematic parameters of the relative RES. However, this type of selection does not provide interposition identification with an arbitrary nature of the movement of the RES relative to the RP, and also assumes a constant angular position of the RP base on the plane. More practical are ways of identifying bearings with RES, in which the procedure for constructing a confidence region (CR) in the form of a circle with a certain radius is used. However, a more correct form of CR is an elliptical CR, since the errors in determining the position of the RES are characterized by an error ellipse, a particular case of which is a circle. Therefore, methods for identifying coordinate information have been developed, in which elliptical CRs are used. In this case, not only the bearings of the RES, but also other measured parameters, for example, estimates of the rectangular coordinates of the RES, calculated on the basis of the triangulation method, can be used as coordinate information. The purpose of the article is to systematize and analyze the developed methods for identifying bearings, which allow one to get a fairly general idea of how to solve the problem of identifying bearings and indirect measurements of the coordinates of radio emission sources in aviation goniometric two-position radio monitoring systems. As a result, a classification of identification methods is given. The existing possibilities and limitations of using various identification methods in solving radio monitoring problems are analyzed. The necessary information on the methods and algorithms for interpositional identification of coordinate information about the position of the RES, using ellipsoidal CRs in solving the identification problem, is given. The practical significance of the presented methods is to increase the likelihood of correct identification of coordinate information, as well as the accuracy of the positioning of RES due to the use of elliptical CRs, which more accurately reflect the regularity of the distribution of errors in determining the position of RES.

Methods of trajectory control of observation in air-based angle-measuring two-position radio monitoring systems. Part 2. Gradient methods

To control and monitor the electronic situation, air-based passive angle-measuring two-position systems radio monitoring can be used. A feature of the functioning of these systems is the fact that the accuracy of the estimation of the coordinates and parameters of the movement of radio emission sources (RES) depends largely on the configuration of the relative position of the receiving positions placed on the aircraft and the RES. Therefore, the problem of optimization the relative position of aircraft and AIR is relevant, and various gradient methods of trajectory control of observation have been developed to solve this problem. Usually in two-position systems one aircraft is the leader, and the second one provides information support. To implement gradient methods, the control of the information support aircraft is organized in such a way that the error of determining the position of the RES at any time is minimal. To fulfill this condition, the information support aircraft must move along a special trajectory, the parameters of which are determined by an algorithm based on gradient optimization methods. The dependence of the error in determining the position of the RES on the relative position of the aircraft and RES and the direction finding accuracy is used as an target function. The article provides information on the gradient methods of trajectory control in the angle-measuring two-position systems, which provide the fastest increase in the accuracy of estimating the coordinates and parameters of the motion of RES for various conditions of practical application in a volume sufficient to obtain a general idea of the ways to solve the problem of trajectory control of an aircraft in the angle-measuring two-position systems. For the trajectory control of the information support aircraft, the gradient method of course guidance was first developed. This method is a relatively simple iterative procedure based on information about the gradient of the quality functional. The disadvantage of this method is the low accuracy of determining the coordinates of the RES at the initial moment of time with a relatively small distance of the aircraft from each other at the beginning of the guidance, as well as in the greater fuel consumption on board the information support aircraft compared to the leading aircraft during the guidance process. To eliminate this disadvantage, trajectory control methods have been developed for two situations of practical application of anglemeasuring two-position systems. The first situation occurs when there is a two-stage procedure of target guidance. At the stage of long-range guidance, aircraft are brought to the RES detection zone by commands from the control center. At the second (short-range) stage of guidance, after the detection of the RES signals by the direction finders of the aircraft, the process of self-homing of leading aircraft to the RES begins and information support for the task solution by other aircraft. For this situation, a modified gradient method of trajectory control of information support aircraft has been developed. The second method to eliminate the disadvantage of the gradient method involves the rejection of the distribution functions of guidance and information support between the aircrafts. It can be used in a situation where the guidance of the aircraft on the RES begins from the moment it is detected on aircraft board. At the same time, the solution of the problem of minimizing the RES location errors is assigned not to one information support aircraft, but simultaneously to both aircrafts. However, mentioned methods do not take into account possible restrictions on the movement of the information support aircraft when forming the control parameters of this aircraft, associated with the presence of dangerous zones for flights, as a result, the flight safety of this aircraft is not guaranteed. For flights in the presence of dangerous zones, the method of trajectory control of the aircraft on the course and the corresponding algorithm of trajectory control of information support aircraft based on the method of gradient projection of the target function has been developed. However, this technique does not guarantee that the flight of the information support aircraft will be carried out exactly on the border of the dangerous zone. In order to eliminate this disadvantage, the method of trajectory control based on the gradient projection method was upgraded using the algorithm of the route guidance method of the aircraft.

Trajectory control methods for observation in two-position angular airborne radio monitoring systems Part 1. Orthogonal methods

Formulation of the problem. Currently, much attention is paid to the practical application and further improvement of two-position goniometric systems (TPGS) airborne radio monitoring, the advantage of which over single-position systems is the possibility of almost instantaneous determination of the location of the radio emission source (RES). A feature of the operation of the TPGS is the dependence of the errors in the positioning of the RES on the «geometry» of the system, i.e. on the size of the base and the position of the RES relative to the base. That is why the problem of optimizing the mutual arrangement of the receiving positions and RES is very urgent. To minimize positioning errors, two groups of trajectory observation control (TOC) methods have been developed, which is due to the variety of conditions for the practical use of aviation goniometric two-position systems and different degrees of their effectiveness. The first group of methods, called orthogonal, provides control of the receiving positions placed on the aircraft, so that the lines of sight of the RES relative to them intersect at right angles. The formation of a right-angled triangulation triangle, at the vertices of which the aircraft and RES are located, can be ensured by appropriate movement of the information support aircraft, or by simultaneously pointing both aircraft. In the first case, it is envisaged to output the information aircraft to an arbitrary point of a straight line, orthogonal to the line of sight «leading aircraft-RES», during the flight along which the best conditions for observation are created, or to a given point on this line. The second group of TOC methods ensures the minimization of errors in the positioning of radioactive sources at each current moment of time. When developing the corresponding trajectory control algorithms that implement the indicated trajectory control methods, direct and indirect optimization methods were used. To date, various TOC methods have been developed, but there is no systematic presentation of them. Purpose. To give a systematized idea of the developed methods of trajectory control of observation in two-position goniometric systems for radio monitoring of the surrounding space, as well as ways of solving the problem of ensuring the best observation conditions and increasing the accuracy of estimating the phase coordinates of the RES in these systems. Results. In the first part of this article, orthogonal methods and algorithms of TOC are considered, the implementation of which contributes to a significant increase in the accuracy of estimating the coordinates of the RES in goniometric two-position airborne radio monitoring systems. Information on the results of experimental studies confirming the effectiveness of the developed TOC methods is also given. Practical significance. The areas of practical application of various TOC methods in solving radio monitoring problems are shown, information about which can be used when choosing rational trajectory control methods for specific conditions of practical application, as well as when developing new TOC methods.

Trajectory control of a two-position system consisting of a strike fighter and a cover fighter, providing an effective solution to the tasks of each of them

The problem of joint guidance of a strike fighter with an on-board radar station operating on radiation, and a cover fighter with an active jamming station operating on radiation, in the interests of improving the effectiveness of group actions of fighters, is due, in conditions of limited radio frequency spectrum, to the occurrence of unintentional interference at the input of the receiver of the onboard radar of the strike fighter, created by the active jamming station of the cover fighter. The purpose of this article is to synthesize the method of trajectory control of a two-position system consisting of a strike fighter and a cover fighter, which ensures the effective operation of the active jamming station of the cover fighter, while maintaining the information support capabilities of the strike fighter in the interests of its accurate guidance in the area of a possible missile launch, by introducing an energy quality indicator into the control signal. The result of the article is: the method of trajectory control of a two-position system as part of a strike fighter and a cover fighter, the results of modeling that allow us to evaluate the effectiveness of the developed method. The practical significance of the materials of the article lies in the fact that the implementation of the developed method of trajectory control of a two-position system as part of a strike fighter and a cover fighter will allow, by taking into account the energy quality indicator in the control signal of the cover fighter, in the form of a realizable suppression coefficient at the input of the on-board radar receiver, to ensure its flight path, ensuring maximum effectiveness of the cover of the strike fighter, while maintaining the ability of the on-board radar of the strike fighter to provide information for the algorithm of its guidance in the zone of possible launch of airto-air missiles.

Methods for estimating coordinates and motion parameters sources of radio emission in goniometric two-position systems airborne radio monitoring. Part 2. Algorithms for nonlinear estimation

Methods for estimating coordinates and motion parameters sources of radio emission in goniometric two-position systems airborne radio monitoring. Part 2. Algorithms for nonlinear estimation

Пространственно-фазовая фокусировка излучателей матричного имитатора на две точки приема

This paper discusses the issues of constructing the configuration of a coherent matrix simulator for modeling echo signals of a two-position system. The condition is formulated in the form of a system of equations that the emitted signals are in-phase at both points of reception. A matrix satisfying this condition provides a simulation of a target in the same position for two spaced antennas. To ensure in-phase operation, it is proposed to use the possibilities of placing the radiators and controlling the initial phases of the signals. Relations are obtained for calculating the coordinates of the 2-point configuration and for calculating the phase addition value. Based on these relations, an algorithm for the synthesis of an extended one-dimensional matrix with the required angular size is developed. It is shown that the points of such a matrix can be located on one straight line. The obtained algorithm was used to synthesize a configuration of seven emitters for the given parameters of the two-position system. Using numerical experiments, the adequacy of the model was verified. Different positions of the point target were set, and a monopulse direction finder model was used to find its direction. The results of numerical experiments confirm the reliability of the theoretical results. They can be used in mathematical and simulation modeling of reflections from real radar targets for two-position systems.

Accuracy characteristics of object location in a two-position system of small onboard radars

Introduction: The search for physical objects in a given area is often performed in automatic mode using small unmanned aerial vehicles equipped with radars. Airborne radar antennas, due to size restrictions, have a small aperture and, accordingly, a wide directional pattern, decreasing the accuracy of determining the angular coordinates of the objects. The increase in the angular coordinate estimation accuracy leads to the increase in the informativeness of such automatic search systems and, consequently, to the increase in the efficiency of their practical use. Purpose: Developing a technique for calculating the parameters of a two-position radar system consisting of two small airborne radars placed on small unmanned aerial vehicles, in order to increase the accuracy of determining the angular coordinates of radiocontrast physical objects. Results: An algorithm is proposed for integrating the data about the coordinates of physical objects detected in the joint coverage area of a two-position system of small airborne radars. It allows you, depending on the observation conditions, to increase the accuracy of determining the azimuthal coordinates by an order of magnitude or more. The aircraft trajectories are calculated on which the accuracy grows, and those on which there is almost no gain in accuracy. Practical relevance: Such two-position airborne small radars can be used in automated systems in order to detect physical object such as people in disaster areas, as well as in systems of collecting and processing data from sensors used for monitoring the state of the environment or man-made objects.

Measurement of the Coordinates of Radio Emission at High Frequencies by Goniometric and Goniometric-Range Finding Methods

The coordinates of radio emission sources at high frequencies are measured using a two-position system of azimuthal-meridional direction finders by a goniometric method. Active antenna lattices of vertical vibrators and synchronized coherent radio receivers with frequency conversion are used in the direction finder stations. The amplitude and phase discrepancies are minimized by preliminary calibration of the receiver channels at the frequencies of the direction finder signals. The measurement results are used to study the mean square deviations of the radio source coordinates for emission of the type for meteorological information from airport networks in the Russian Federation and neighboring countries, radio stations with standard frequencies and times, and telecoded and continuous transmissions. The attainable accuracy of the measurements is analyzed as a function of spatial position of the direction finders, path lengths, and fluctuations in the electrical parameters and spatial distribution of the ionized layers of the atmosphere leading to changes in the beam trajectories and anomalous errors in measurements of the ray trajectories and anomalous errors in measurements of the directions of arrival of the radio waves at different times of the year and day. It is shown that in the lower part of the high frequency band the error in measuring the coordinates of the radio sources by the goniometric system is 4.7%, and that as the frequency approaches the upper boundary this indicator increases by a factor of 1.2. Range finding of signals at a single point in space and measuring the height of the layers of the atmosphere using vertical ranging stations yields coordinates of the radio sources by the goniometric-range finding method. Measurements of the coordinates of objects by the goniometric-range finding method can be carried out with a mean square deviation equal to 11–13% of the distance.

SIMULATION OF ECHO SIGNALS OF TWO-POSITION SYSTEMS USING COHERENT EMITTERS

The paper deals with the task of simulating echo signals of a radar system for two-position systems. Relations have been obtained for calculating the coordinates of the emitters of a matrix simulator in the form of a system that satisfies the conditions of in-phase conditions of signals at two receiving points. The condition of signal synchronization is achieved when the difference in distance from the emitters of the matrix to the receiving points is an integer number of wavelengths. Based on the obtained relations, an iterative algorithm for the formation of a matrix of coherent emitters has been developed, which allows synthesizing matrices of any sizes. An example of the implementation of the iterative algorithm showed that by selecting the values of the distances from the matrix emitters to the receiving points, the emitters can be located almost on one line. The obtained theoretical results are confirmed by numerical simulation data.

MATRIX SIMULATOR OF ECHO SIGNALS OF TWO-POSITION RADAR STATION

In this paper echo signals simulation task of two-position systems was considered. A matrix simulator composed of coherent transmitters is offered as a solution. Herewith in order to provide independent imitation for each antenna of the Radar station it’s suggested to use the additional transmitters correcting simulated echo signals at the receiving points. Correction is based on the principle of phase compensation of the signals from emitters that are equidistant from a specific receiver point. The configuration of the minimum possible number of emitting points was obtained, which has the potential for independent control of the apparent radiation center. Shown that the compensation condition of the signals of the transmitter group is not enough for independent control of the apparent radiation center. The sufficient independence conditions were formulated. The obtained theoretical results were confirmed by the data of numerical experiments.

Amplitude-Hyperbolic Method of Passive Location of a Radiation Source

A new method for ranging and locating a radiation source is proposed for a two-position system that detects an amplitude and difference of instances at which a wave arrives at a receiving position. Equations that make it possible to study the procedural error and accuracy characteristics of the method for various observation conditions and the results of a computational experiment are presented. Recommendations on applying this method are given.

Energy direction finding method taking into account the curvature of the Earth and interference

This paper presents a method using a two-position system to determine the spatial coordinates of a moving radiation source from one bearing measurement and relative energy measurements of the received signal taking into account the effect of its reflection from the Earth surface. The passive location problem is solved for low elevation angles taking into account the curvature of the Earth and using a polynomial model of source motion. An algorithm for the parametric identification of this model using a measurement sample of increasing size in a regularized formulation is developed, and the accuracy characteristics of the method are analyzed.

Measurement of the Depth of Propagation of a Beam in Sensing of a Uniform Scattering Layer by a Two-Position System. Part 2

A two-position scheme that comprises a backscatter lidar and backscatter nephelometer for measurements of the geometric form factor is proposed. The parameters of the beam sensing depth in a scattering medium with overlap of the field of views within the medium, which are indicators of the extinction coefficient and the geometry of the scheme, are considered. The nephelometer mode is optimal for measurements of the extinction coefficient. With the use of a complete set of indicators, it becomes possible to estimate the precision of measurements of the extinction coefficient within a layer.

Experimental validation of the scenario of the object microstructure determination using a two-position lidar system: a screen with random transmittance modulation

The two-position system is assembled on the basis of the bistatic sensing scheme. For the screen with random holes, three calibration stages were implemented: the preliminary, local, and microphysical calibrations. The coefficients relating the parameter of angular distortion of the beam passed through the screen to the transverse hole size were determined. For a halfplane-shaped light source, this coefficient is C 3 = 0.7(21 %), for a point source, C 3 = 0.8(14 %). These coefficients are close to that relating the diffraction angle of the plane wave at a hole to transverse size C = 0.6.