PRIMARY AND SECONDARY ALGORITHMS FOR SIGNAL PROCESSING IN ACTIVE APERTURE SYNTHESIS SYSTEMS

2019

Авіаційно-космічна техніка та технологія, Vol 0, Iss 6, Pp 54-67 (2019)

A method for processing spatio-temporal radio signals, which allows the formation of high spatial resolution images from aerospace carriers, has been synthesized. In this case, a swath is ±15° from the nadir relative to the flight line is considered. Traditionally this swath is not visible from aerospace carriers. A block diagram of an active-passive type radar is proposed. Initially the image obtained at the output of such a radar has a low quality of visual perception. Such image is called primary, since it was obtained at the stage of primary signal processing. The physical sense of such image is investigated. It approximately represents the operation of convolution of the ambiguity function with a spatial function proportional to the ideal image. The physical sense of the ideal image depends on the characteristics of the imaging system. In the problem under consideration, this is the specific radar cross section. In order to improve the quality of the image it is proposed additional processing (filtering). The paper substantiates the method of filtering (secondary processing) of images based on the solution of the inverse integral equation. It is shown that the exact solution to this equation is difficult to obtain because the form of the ambiguity function is not known exactly and can be estimated only approximately and, in addition, not for each ambiguity function it is possible to obtain a non-singular solution of the inversion equation. Therefore, an approximate solution to the problem is given. It solution is sufficient to solve practical problems of improving image quality. Using numerical simulation methods, the influence of the error in determining the shape of the uncertainty function on the task of improving image quality is studied. Examples of primary and secondary images obtained at the output of wideband active aperture synthesis systems with various geometries of spatially distributed antenna systems are given.

article

English
Ukrainian

National Aerospace University «Kharkiv Aviation Institute», 2019.

обработка сигналов, обработка изображений, формирование изображений высокого пространственного разрешения, система активного апертурного синтеза, сверхширокополосные пространственно-временные сигналы, Motor vehicles. Aeronautics. Astronautics, TL1-4050