A.S. Petrov1, V.P. Makarov2

1, 2 JSC Lavochkin Association (Khimki, Russia)

1 aspetr50@mail.ru, 2 makarovVP@laspace.ru

When digitizing an echo signal reflected from the earth's surface, its sampling frequency, performed using an analog-to-digital converter (ADC) installed on a platform with synthesized aperture radar (RSA) equipment, is selected in such a way that it exceeds the limit determined by Kotelnikov's theorem with the minimum necessary coefficient. With further digital processing of the received signal to improve the detail of the reproduced image, the task of performing its resampling arises.

The goal of the article is to identify the implementation features of the algorithms for modeling the procedures of oversampling a two-dimensional SAR signal and to estimate the point target response function parameters.

Algorithms and software modules have been developed for modeling the procedures of resampling a two-dimensional SAR signal by adding zeros to an array of its samples and using the Kotelnikov series. The results of evaluating the response function of a synthesized aperture radar to a point target using signal oversampling procedures have been presented. The developed algorithms expand the possibilities of applying signal oversampling procedures by supplementing the original array in the spectral region not only with internal, but also with external zeros. Examples of oversampling the spectrum of one-dimensional signals by adding zeros in the time domain of the vector of their samples from the left or right side, and finally, simultaneously from two sides, have been given. Examples of oversampling two-dimensional signals in the time domain by supplementing the original centered spectrum with external zeros, and the non-centered spectrum with internal ones have been also given. A procedure for oversampling the signal by interpolation using a truncated Kotelnikov series has been described. To speed up the calculations, special tables should be used for the coefficients of this series. This method, unlike the first one, allows you to create an uneven grid of signal counts, but loses to it in speed.

Petrov A.S., Makarov V.P. Oversampling of a digital signal when processing a two-dimensional SAR response function to a point target. Achievements of modern radioelectronics. 2024. V. 78. № 9. P. 17–26. DOI: https://doi.org/10.18127/j20700784-202409-02 [in Russian]

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