Introduction. With the development of hardware and computer systems, which improve qualitative characteristics of synthetic aperture radars, with their dimensions limited, many new systems have appeared that allow using more accessible and widespread mobile platforms such as a car, quadcopters, unmanned aerial vehicles (UAV). Problem. The use of new types of platforms leads to additional distortions associated with features of the geometry of the radar performance and more severe trajectory instabilities. Thus, new synthetic aperture radar systems should have special requirements for both software and hardware, which differ from classical systems. Objective. The aim of the work is the comparison various algorithms that are used in modern radiovision systems to obtain high-quality radar images that can be integrated into various kinds of mobile platforms. Methods. The method of frequency scaling and various modifications of this method are taken as a basic algorithm, including additional algorithms for compensating trajectory instabilities. For comparison of algorithms, the system geometry for automobiles and aircraft systems are considered and simulations were performed with the presence of point reflectors at different distances and the distortion of the platform motion. Results. The difference of the considered algorithms in the form of flowcharts and mathematical formulas is shown. Based on results of the simulation the use of the basic frequency scaling algorithm at distances corresponding to the geometry of the automobile system leads to the distortion of the response along the azimuth. In addition, the use of the modified algorithm for compensating trajectory distortion allows correct focusing the targets at different distances. Conclusion. The proposed combination of modified algorithms of trajectory distortion and frequency scaling allows focusing the image evenly throughout the frame and improving the quality of the image in the near zone.
The article discusses the features of the application of coherent accumulation in passive radar systems, operating on signals of telecommunication sources. A technique for coherent accumulation is developed. Factors limiting signals time accumulation are discussed. The dependences of range of the system and signal/noise ratio of the received signal from accumulation time are shown. The conclusions about the effectiveness of coherent accumulation in passive radar systems are made.
The article provides an overview of existing methods of combating a clutter considering modern domestic and foreign sources. The authors examined the methods of combating a clutter in transmission path, antenna path, and intermediate frequency path as well as in blocks of primary and secondary radar data processing. The paper presents statistical and spectral methods.
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