Phase Direction Finders Research Articles

The application of neural networks in the problem of radio monitoring with the use of a two-coordinate radio direction finder and the estimation of their efficiency

Problem statement. Measuring bases of two-coordinate phase direction finders (PDF), as a rule, are located along the same line, while bearing occurs in two planes independently. The procedure for determining the bearing in this case consists in restoring the true wave front and is quite computationally expensive. The study of PDF using a neural network with simultaneous use of information from all possible combinations of measurement bases is of particular interest from the point of view of evaluating the possibility of increasing the probability of correctly eliminating the ambiguity of bearing and increasing the accuracy of bearing, reducing computational costs and reducing the time to determine the bearing. Goal. Evaluation of the effectiveness of the use of artificial neural networks (NN) for direction finding of radio emission sources (RES) in solving radio monitoring problems using two-coordinate PDF, evaluation of the possibility of increasing the probability of correct elimination of ambiguity of bearing and increasing the accuracy of bearing when using all measuring bases of PDF. Results. A model of two-coordinate PDF based on NN has been developed, which makes it possible to evaluate the effectiveness of RES bearing in two planes with variations in model parameters and initial data. The obtained modeling results allow us to conclude that it is possible to create a two-coordinate PDF based on NN. The evaluation of the effectiveness of bearing shows that PDF based on NN has a commensurate accuracy of bearing and a high probability of eliminating ambiguity compared with PDF using classical methods and is somewhat inferior to them at high values of the phase measurement error in the receiving channels. Practical significance. The use of artificial neural networks (NN) for direction finding of radio emission sources (RES) in solving radio monitoring problems and further research on their development will improve the accuracy and reliability of measurements while reducing computational costs.

Methodology for processing information of a multi-base phase direction finder and assessing the quality of results, taking into account failures and deterioration in the operation quality of individual MPDF bases

When conducting radio-electronic monitoring (SEM) by systems of various types of basing, phase direction finding methods are widely used. To obtain both high accuracy and unambiguity of direction finding, a reusable phase direction finder (MBFP) is used. In the literature, quite a lot of works are devoted to methods for optimizing MBFP structures. In this paper, the issues of automation of accounting for failures or deterioration of the quality of work of individual MBPF databases in the process of processing direction finding information obtained during the management of SEM are considered. The determination of the bearing (guiding sine) on the radiation source with the phase direction finding method is carried out by a set of phase differences obtained at the output of a multi-phase phase direction finder (MBFP).

Алгоритм определения направления на источник радиоизлучения в двухканальном фазовом радиопеленгаторе

The article presents a block diagram of a two-channel phase direction finder with amplitude modulation of the signal. The features of the formation of a radiation pattern in the form of a cardioid using non-directional biconic antennas are considered. An algorithm for estimating the bearing using a limited number of antenna elements (two direction finding pairs) is proposed. A variant of increasing the number of bearing estimates for one contact with a radio source based on the use of a sliding buffer is presented.

Simulation of an Improved-Accuracy Monopulse Phase Direction Finder Based on an Adaptive Antenna Array

Simulation of an Improved-Accuracy Monopulse Phase Direction Finder Based on an Adaptive Antenna Array

Possibility of using a microwave photonic link in a phase direction finder of the microwave range under dynamic temperature effects

Possibility of using a microwave photonic link in a phase direction finder of the microwave range under dynamic temperature effects

Methods for determining the phase difference of the output signals for the receiving elements of a phased antenna array in a radiophoton circuit with parallel and series pairwise connection of electro-optical modulators

Obtaining accurate phase values of the output signals for the receiving elements of a phased array antenna is one of the crucial issues relating to radio-photon technologies in radar and radio communication. The paper considers measuring the phase difference of the output signals for the receiving elements of a phased array antenna using electro-optical Mach–Zehnder modulators as part of a radio-photonic device. The dependences of the output signals of the optical signal receivers and the phase difference of the output signals for the receiving elements of the phased antenna array in the radio-photonic scheme are formalized for different variants of the connection of electro-optical Mach–Zehnder modulators. The authors propose the methods for determining the phase difference of the output signals for the receiving elements of a phased array antenna based on parallel and series connection of electro-optical Mach–Zehnder modulators into radio-photonic devices. A comparative assessment of the proposed methods is carried out. It is shown that the method based on the determination of the phase difference with the parallel connection of electro-optical modulators produces 1.58 times less error than the method with the series connection. The description of the radio-photonic scheme of the phase direction finder is presented. The proposed scheme provides high accuracy in measuring the phase difference of the output signals for individual receiving elements of a phased array antenna. The results of the work can be applied by specialists in the field of advanced radar and radio communication systems.

Using the Maximum-Likelihood Method for the Angular Resolution of the Signal Sources in Multibase Phase Direction Finders

Using the Maximum-Likelihood Method for the Angular Resolution of the Signal Sources in Multibase Phase Direction Finders

Hydroacoustic phase direction finder with amplitude-modulated navigation signal

We consider a phase direction finder with an ultrashort base and the use of an amplitude-modulated navigation signal. It has advanced functionality in positioning systems for underwater objects placed on various surface and underwater carriers.

On the characteristics of the phase direction finder of the hydroacoustic system drive for delivering autonomous uninhabited underwater vehicle

The navigation characteristics of a phase direction finder with an ultra-short base of a hydroacoustic system delivering an autonomous uninhabited underwater vehicle to a given underwater object using two delivery scenarios are considered.

Using the Maximum-Likelihood Method for the Angular Resolution of the Signal Sources in Multibase Phase Direction Finders

Using the Maximum-Likelihood Method for the Angular Resolution of the Signal Sources in Multibase Phase Direction Finders

Однопозиционный метод определения координат источника радиоизлучения на земных трассах по совокупности отражений его сигнала от местных предметов

Electronic intelligence is an important element of electronic warfare, which «is not announced and never stops». The purpose of electronic reconnaissance is to detect the emitting radio-electronic means of a potential enemy, to determine its location and radiation parameters using passive (non-emitting equipment). Electronic warfare, even in peacetime, is a promising area of development. The use of passive methods allows work to be carried out covertly, without detection. The peculiarity of the proposed method is that a priori information about the objects that reflected the signal is not required. Determination of the coordinates of the emitter is carried out by determining the delay between the arrival of the direct signal and the set of reflections from the terrain. The use of detailed, for today, satellite maps of the terrain allow with some accuracy to determine the coordinates of reflecting objects on the ground. The coordinates of the receiving point can also be determined with high accuracy using global navigation systems. The data entered the computer and the recording of signals obtained as a result of observing the air allows us to determine the coordinates of the radio emission source. The algorithm proposed in the article allows reducing the number of receiving points to one and using a phase direction finder to determine the direction of signal arrival. Evaluation of the potential accuracy of the method showed the possibility of practical application, while better results can be obtained when improving the algorithm in terms of improving the algorithms for determining the times of arrival of signals, algorithms for their extraction and post-processing of experimental data.

Вычисление топоцентрических координат источника радиоизлучения по результатам измерений фазового пеленгатора на борту подвижного объекта

The algorithm to calculate the azimuth and the elevation angle on the source of radio emission in the topocentric system of coordinates is suggested according to the measurements done by the phase direction finder located on board a mobile object. The position of an aerial system direction finder to the earth topocentric system of coordinates can be changed. The change in the position of the aerial system influences the accuracy of calculating the bearings. The method to reduce the errors of bearing by iteration method is considered. The checking procedure of the algorithm by mathematical modelling is carried out.

Algorithm for Eliminating of the Limiting Disambiguation of Measurement Made by Phase Radio Direction Finders by Sorting Out the Abnormally Large Errors

The aim of the article is to find the upper probability limit of the measurement results to correct disambiguation in case of multi-base phase direction finders, where all bases are ambiguous. Direction finding is done using the maximum likelihood method based on a set of measured phase differences and an algorithm of rejecting (erasing) abnormally large measurement errors. The theoretical background of the article is the maximum likelihood method applied to disambiguate results of the phase measurements in multi-base measuring systems. The physical meaning of the method is that if the disambiguation process is correct, the results of angular measurements for each base are grouped around the true value of bearing. The mathematical background of the article are methods of linear algebra based on the geometric interpretation of disambiguation measurement results. We obtained formulas for calculating upper bounds for the probability correct disambiguation of measurement results, which are applicable to direction finders with linear, planar and conformal antenna arrays. The obtained theoretical relations are exemplified by a numerical calculation of error probability including the upper bounds for a specific three-base direction finder 'bad' measurement results. The calculations proved effectiveness of the proposed algorithm, which depends on the accuracy of phase measurements. The proposed algorithm is applicable not only in case of the direction finders, but also for other multi-base phase measurements. The work may be interesting for designers of direction finders in terms of achievable accuracy of measurement results even if some of the results are rejected.

Анализ разрешающей способности обзорных фазовых радиопеленгаторов

Анализ разрешающей способности обзорных фазовых радиопеленгаторов

The research of temperature instability influence of fiber optic communication line in phase direction finder channels on peleng accuracy

In the article the influence of optical fiber temperature change to phase shift between optical signals in transmission channels is considered. The method for influence assessment of temperature phase shift on bearing accuracy is proposed. The results of experimental researchers and calculations are presented.

Extreme Probabilistic Characteristics of the Measurement Disambiguation in Multiscale Phase-Measuring Systems

We determine the upper limit on the correct measurement disambiguation probability in multiscale phase-measuring systems in which all scales are ambiguous. The measured value is estimated by the maximum likelihood method from the total of measured phase differences supplemented by an algorithm for rejecting (erasing) measurement results with anomalously large errors. Errors that exceed one-half of the main lobe of the likelihood function are considered anormalously large. The results are obtained by the methods of linear algebra with a geometric interpretation of the measurement disambiguation process in the space of total phase differences. The method was applied to phase direction finders, but can easily be adapted to other types of multiscale phase radio systems.

PERFORMANCE ANALYSIS FOR DIRECTION-FINDING CIRCULAR ANTENNA ARRAY

This paper considers circular antenna arrays comprised of symmetrical dipole radiators applied in communication, navigation and monitoring systems. Despite their widespread use, a number of significant issues is underinvestigated. Among them are frequency dependence of the antenna factor (the ratio of the electric field intensity module to the voltage amplitude at the load connected to the output terminals) of the circular antenna array elements in the correct electrodynamic setting. The purpose of this paper is to analyse the antenna factor frequency dependence of a single dipole antenna with different geometry and load both in free space and as circular antenna element. The estimation of phase difference error between the circular antenna array elements caused by their cross coupling is also of interest.Specific expressions are obtained for the antenna factor of the dipole antenna for single-mode and three-mode approximations. The limits of their applicability in frequency band are considered. The solution to the coupled integral equations is obtained using the Galerkin method with piecewise sinusoidal current distribution and with an arbitrary number of basis functions for eight- and four-element circular antenna array. This solution may be generalized to an arbitrary number of circular antenna array elements. It is demonstrated that to improve the antenna factor frequency dependence it is advisable to use dipole antennas with high-resistance load, as well as with large diameter. Phase errors for different circular antenna array element signals are considered with respect to the reference element. The dependence of these phase errors on the circular antenna array geometry is presented. It is concluded that there are significant oscillations of the antenna factor when the dipole is the part of the circular antenna array. They are caused by cross coupling between the circular antenna array elements, which significantly depend on the element spacing. The results presented may be of interest to phase direction finder development engineers.

Physical and Mathematical Questions on Signal Processing in Multibase Phase Direction Finders

Questions on improving the accuracy of multiple-base phase direction finders by rejecting anomalously large errors in the process of resolving the measurement ambiguities are considered. A physical basis is derived and calculated relationships characterizing the efficiency of the proposed solutions are obtained. Results of a computer simulation of a three-base direction finder are analyzed, along with field measurements of a three-base direction finder along near-ground paths.

Алгоритм устранения неоднозначности и вычисления пеленга в многобазовых фазовых пеленгаторах

Алгоритм устранения неоднозначности и вычисления пеленга в многобазовых фазовых пеленгаторах

APPLICATION OF DISTRIBUTED ANTENNA SYSTEMS FOR DETERMINATION OF RADIATION SOURCE COORDINATES WITH USE OF PHASE METHOD IN FRESNEL ZONE

Background. Talking about evolution of passive radar systems and multifunction antenna systems, it is necessary to acknowledge that distributed antenna systems (DAS) are supposed to be widely spread in the very near future in many areas of human activity, such as organization of high-quality mobile communication in large offices, shopping centers, fitness buildings and so on. Structurally, DAS consist of different groups of antennas and base stations with active and passive repeaters of radio signals. Generally, mutual location of such antennas and base stations can be chosen experimentally according to the criterion of service area maximization. For the further quality of service improvement, it is necessary to use smart antennas in DAS as basic structure elements. The use of smart antennas will allow tracking the subscriber`s (or SOR – source of radiation) location by means of direction-finding (DF) and to increase radiation power of radio signal towards SOR thus decreasing interference to other subscribers. It is important to note that amplitude methods of DF are unacceptable in this case because base stations have antenna beam patterns which are rather wide. Use of phase methods for direction finding is actual but constrained because of electromagnetic waves (EMW) multipath propagation and large DF errors caused by the following reason – it happens that SOR is located in Fresnel zone of direction-finder antenna system. So, consideration of the phenomenon of EMW front curvature in DAS is very important in order to construct direction-finders. Objective. Consideration of EMW phase front sphericity (curvature) and its influence on the accuracy of SOR coordinates determination measured by DAS phase methods. Scheme technical decisions of phase direction-finders (PDF) based on this process are also represented. Methods. To study the effect of the EMW phase front curvature on the accuracy of determining the coordinates of the SOR analytical dependencies are synthesized. Calculations of the direction characteristics, errors in determining the phase shifts between the antenna elements of the phase direction-finder, as well as the error in determining the distance to SOR in the Fresnel zone as a function of the range to SOR and its bearing were made based on MathCad 14 program. Results. During the process of SOR angular coordinates determination in Fresnel zone with use of EMW phase front curvature оn the basis of planar antenna array, it is necessary to execute consistently two operations: 1) to define the fact of presence of EMW phase front curvature; 2) to switch PDF from the mode of bearing and tilt angles estimation (when it is in plane phase front) to the mode of bearing and tilt angles estimation (and also distance to SOR if needed) with phase front curvature of EMW. Taking into account the analysis relating to errors of bearing angle measurements in Fresnel zone (depending on the location of rough, but exact bases, for three-element sparse LAA) it is possible to conclude that their position doesn’t impact on exactness of bearing angle measuring in PDF. But to support more exact determination of SOR distance they must be placed in the center of exact, but ambiguous bases of PDF. Conclusions. Failure to take into account EMW phase front curvature from SOR harmonic signal leads to errors of SOR coordinate calculation under conditions of its location in Fresnel zone and absence of other SORs. Knowledge of distance to SOR can be used in passive radar systems, in radio monitoring systems of radio interference sources which have bearing angles equal with useful SOR ones, but located on different distances from useful SOR. This knowledge can also be used in mobile communication networks to strengthen signal level on certain distance with EMW energy focusing, in vehicle control systems on the basis of the satellite navigation systems etc.