Satellite-borne synthetic aperture radar (SAR) imaging method based on Doppler cubic term estimation

Abstract

The invention discloses a satellite-borne synthetic aperture radar (SAR) imaging method based on Doppler cubic term estimation. The method comprises the following steps of: 1, reading echo simulation data of a satellite-borne SAR sliding beam bunching mode; 2, processing the echo simulation data, and thus obtaining a two-dimensional frequency domain signal; 3, setting a Doppler cubic term initial value, an iteration threshold and an iteration step length; 4, acquiring a signal which is subjected to distance compensation; 5, acquiring an imaging result signal; 6, acquiring the maximum value and position of a one-dimensional signal; 7, acquiring a left first side lobe peak of a one-dimensional signal main lobe; 8, acquiring a right first side lobe peak of the one-dimensional signal main lobe; 9, acquiring an absolute value of difference between the left first side lobe peak and the right first side lobe peak; and 10, comparing the absolute value with a threshold Th, and judging according to a comparison result. The method has the advantages that a high-accuracy Doppler cubic term is obtained by using an iteration method, phase errors brought by the conventional slope distance model under the condition of high resolution are compensated, and a satellite-borne SAR focusing image is obtained, so the effectiveness and accuracy of the method are verified.

Description

technical field [0001] The invention belongs to the field of signal processing, in particular to a spaceborne synthetic aperture radar (Synthetic Aperture Radar, SAR) imaging method based on Doppler cubic term estimation. Background technique [0002] Spaceborne SAR is an advanced space-based information acquisition payload, and an important means of obtaining control information rights. It can overcome the limitations of cloud, fog, rain, snow and dark night conditions to image ground targets, and can realize all-day, All-weather, high-resolution, large-scale surface-to-earth observation has a wide range of applications in ocean observation, precision agriculture, environmental protection, disaster monitoring, resource exploration, geological surveying and mapping, government public decision-making, etc., and plays an irreplaceable role in other space remote sensing methods. effect. It has been 60 years since the concept of synthetic aperture was proposed. During this peri...

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Problems solved by technology

However, when there is a Doppler cubic term error, it will lead to asymmetric distortion of the imaging compression azimuth output, that is, the right side lobe level increases, and the main lobe broadens to the left, and the side lobe level of this Increasing the height in the case of a strong point target will cause a double image of the target on the image, which seriously affects the azimuth imaging quality of the spaceborne SAR. Therefore, under the condition of high resolution, the accurate calculation of the Doppler cubic term is particularly important.

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