M.Ja. Guseynov - Engineer, JSC «Concern «VEGA». E-mail: maksim_guseynov92@mail.ru T.A. Lepekhina - Ph.D. (Eng.), Head of Department, JSC «Concern «VEGA». E-mail: tatonika@inbox.ru V.I. Nikolaev - Deputy Head of Department, JSC «Concern «VEGA». E-mail: vnikolaev65@inbox.ru A.M. Tarasenko - Engineer, JSC «Concern «VEGA». E-mail: asianna@list.ru

Multi-mode airborne radar function set diversification in the part of synthetic aperture mode for Earth mapping requires instrument range resolution improvement. Proper sounding signal spectrum expansion is supposed to be obtained using the available facility of pulse carrier stepped tuning during the acquisition. This technique known as Interperiod Spread Spectrum (ISS) enables the expected improvement without replacing of currently used narrowband IF circuits, modulator and digital acquisition system. In order to analyze the effectiveness of the method above, simulation is performed to compare SAR impulse response function characteristics and peculiarities for various sounding signal patterns in SAR modes. Two variants of carrier tuning sequence are considered in the paper: periodic linear order known from former publications and random order with uniform distribution introduced by the authors. Two in-pulse modulation rules such as the chirp and the M sequence have been researched. The technique of ISS proved to be sound for range resolution improvement in all cases, the resolution being close to that of a wideband SAR having spectrum bandwidth equal to considered carrier tuning range. However, tuning order optimization was required to provide minimum peak sidelobe levels of two-dimensional response function. The peculiarities of radar image synthesis based on sounding signal discrete tuning in terms of mathematics are also analyzed. A methodology is formed to distinguish the directions of further research of ISS technique capabilities.

 

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