Abstract
Conventional synthetic aperture radar (SAR) imaging algorithms usually require a period of time to process data that is longer than the time it takes to record one synthetic aperture or that corresponding to an adequate azimuth resolution. That is to say, the real-time processing system is idle during the long data recording time and the utilization of computational resources is low. To deal with this problem, a real-time imaging algorithm based on sub-aperture chirp scaling dechirp (CS-dechirp) is proposed in this paper. With CS-dechirp, the sub-aperture data could be processed to form an image with relatively low resolution. Subsequently, a few low-resolution images are generated as longer azimuth data are recorded. At the stage of full-resolution image generation, a coherent combination method for the low-resolution complex-value images is developed. As the low-resolution complex-value images are coherently combined one by one, the resolution is gradually improved and the full-resolution image is finally obtained. The results of a simulation and real data from the GF3-SAR validate the effectiveness of the proposed algorithm.
Highlights
Spaceborne synthetic aperture radar (SAR) can perform two-dimensional high-resolution imaging of ground targets at a long distance and in all-weather and all-day conditions [1,2,3], which makes it a key method for real-time information acquisition
The real-time processing system is idle during the long data recording times and the utilization of computational resources is low
This paper proposes a real-time imaging algorithm based on sub-aperture chirp scaling dechirp (CS-dechirp), which can perform imaging processing while the data are recorded and without waiting for a full-aperture time
Summary
Spaceborne synthetic aperture radar (SAR) can perform two-dimensional high-resolution imaging of ground targets at a long distance and in all-weather and all-day conditions [1,2,3], which makes it a key method for real-time information acquisition. Some classic algorithms such as the range Doppler algorithm (RDA) [7], chirp scaling algorithm (CSA) [8], range migration algorithm (RMA or omega-k algorithm) [9], and polar format algorithm (PFA) [10] can obtain well-focused images, which are usually used in SAR real-time processing These algorithms usually process data in a time period longer than that required for one synthetic aperture or that corresponding to an adequate azimuth resolution [11,12]. The real-time processing system is idle during the long data recording times and the utilization of computational resources is low This problem is obvious in spaceborne SAR systems due to their long radar range, high azimuth resolution, and long synthetic aperture length [13].
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