Yu.N Gorbunov1, M.A Epifanov2

1 Fryazino branch of Kotelnikov Institute of Radioengineering and Electronics of RAS (Moscow, Russia)

1 JSC "Central radio-research institute named after academician A.I. Berg" (Moscow, Russia)

2 Science Research Institute of Space Device Engineering, Branch of JSC "URSC" (Moscow, Russia)

1 gorbunov26.10.48@gmail.com, 2 epifanov_ma@orkkp.ru

Direction finding of sources of electromagnetic radiation (EMR) seems to be an important task in monitoring radio emissions in RTS: passive radar, aviation and space reconnaissance, detection of radio buoys in rescue systems, which is extremely important. Direction finders that solve this problem implement a panoramic view in the azimuthal direction and rejection of interference from local objects (LP) in the angular-local plane, which is achieved by using volumetric M-channel digital volumetric antenna arrays (AR). In such ARs, according to the well-known classification of processing types, we are dealing with spatial-temporal (ST) signal processing. The received signal (field) is quantized in time and space by the corresponding placement of the receiving elements (RE) of the digital AR along the aperture of the receiving antenna, and the signals from the outputs of individual PEs are sampled in time and quantized in level. The goal of the work is to implement digital arrays with MF signal processing, when, in conditions of multipath reception, by stabilizing the position of the phase center (PC), along with the main task of measuring bearing, the problem of reducing measurement errors is solved. The solution to the problem is new. At present, taking into account restrictions was implied, but the task was not set functionally, because in the theory of potential noise immunity V.A. For Kotelnikov, the energy E and the sensitivity of the receiver were important, and the processing algorithms were of indirect importance. It was also assumed that there were no hardware limitations. In this article, the consideration is carried out for small-element M-channel volumetric direction finders, where processing algorithms are important and hardware and resource limitations are taken into account. To construct panoramic direction finders in the azimuthal plane, flat phased arrays are usually used, horizontally oriented to the surface of the earth or water. In the presence of reflections from local objects (LP), “multipath” effects occur, bearing measurement errors appear, the useful signal (direct transmission) is filtered by spatial digital filter methods, which is achieved by placing the receiving elements of the phased array not only along the x, y coordinates of the horizontal plane, but also along z coordinate (height). In this case, the phased array becomes volumetric (3-coordinate), and complex conjugate zeros are used in the digital filter. Since the change in bearing (coordinates of a point on the image) during a pack of N time samples can be neglected, the instrumental error is reduced due to Monte Carlo randomization. Randomization (random – random) involves the artificial introduction of randomness into the parameters of signals and processing devices: quantization thresholds, weighting coefficients (WK) – their signs. The space-selective properties of the spatial CF are specified by introducing the VC correlation. The synthesis of optimal bearing estimation is based on the principle of “whitening” correlated passive interference (PP) from MP, which determines the achievement of high accuracy of direction finding in the conditions of using rough statistics (GS), randomized (linearized) by additional “digital noise” with zero average underlying mathematical model of chaotic VCs. In conditions of limited hardware and software resources, the urgent problem of measuring the bearing of EMI sources is solved in conditions of signal processing against the background of inhomogeneous correlated “multibeam” PPs. Along with the deterministic VC CFs, their chaotization was applied and the problem of preserving the direction finding function was solved while simultaneously realizing the possibility of implementing a set of conflicting requirements for direction finding, resolving EMIZ sources, implementing panoramic capabilities, accuracy, resolution, and stabilizing the probability of false alarms (VLT).

Practical significance. The relevance of the proposed approach to rejecting multi-beam PPs is substantiated – spurious reflections from local objects (LPs), reducing instrumental errors in bearing measurements by stabilizing the position of the FC of a digital array and reducing its visibility in the wavelength ranges coinciding with electronic reconnaissance systems (RTR) – reducing brightness antenna shiny points (electrodynamic edges), VLT stabilization.

Gorbunov Yu.N, Epifanov M.A. Direction finding of sources of electromagnetic radiation signals by digital antenna arrays with invariant phase center. Electromagnetic waves and electronic systems. 2024. V. 29. № 2. P. 55−67. DOI: https://doi.org/10.18127/ j15604128-202402-06 (in Russian)

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