A.A. Monakov1

1 St. Petersburg State University of Aerospace Instrumentation (St. Petersburg, Russia)

Range cell migration is one of the main reasons of deterioration of radar images in radars with synthesized antenna aperture (SAR). Nowadays there are two groups of signal processing algorithms for SAR, which permit to compensate the range cell migrations. The first group includes algorithms that use the recalculation of the signal from the coordinate system "slant range – azimuth" into the system "along‑track range – cross‑track range" using different mathematical methods of functional interpolation. Since the conversion from one coordinate system to another is a fairly costly process, the algorithms of the first group require a significant amount of computing power in implementation, which is a serious drawback of the algorithms of this group. Algorithms of the second group do not use interpolation and are based on transformation of the range cell migrations into the corresponding phase shifts with their further compensation. These algorithms are not inferior in quality to the interpolation methods, but they are also much faster due to the application of fast procedures of the Fourier analysis in calculations. Unfortunately, these methods are difficult to be realized in onboard signal processors because the number of calculations is also large.

The article synthesizes a range migration compensation algorithm that does not use interpolation methods. The synthesized algorithm is a modification of the well-known Keystone Transform Algorithm (KTA). The proposed algorithm is based on the Chirp Scaling Algorithm and the fast procedures of the Fourier spectral analysis. Implementation of the chirp scaling permits to avoid the interpolation in the KTA. Besides the number of complex multiplications is reduced in the proposed algorithm. Thus, the proposed algorithm has a high computational speed and can be used for any sounding wideband signal. Computer simulation proves the high efficiency of the algorithm. The algorithm can be implemented in side looking SAR to synthesize radar images of high spatial resolution.

Monakov A.A. Algorithm of range migration compensation via the keystone transform without interpolation. Achievements of Modern Radioelectronics. 2022. V. 76. № 12. P. 46–54. DOI: https://doi.org/ 10.18127/j20700784-202212-07 [in Russian]

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