Frequency-modulated continuous wave SAR motion compensation method based on triangular wave modulation

Abstract

The invention provides a frequency modulated continuous wave SAR motion compensation method based on triangular wave modulation, which comprises the steps of performing distance compression and videophase removal on positive frequency modulated signal echoes and negative frequency modulated signal echoes respectively to obtain distance compressed images corresponding to positive frequency modulation and negative frequency modulation; performing SAR motion error estimation based on the motion error of the distance frequency; and applying the estimated motion errors to SAR motion compensation imaging processing. According to the invention, a miniature low-precision POS system does not need to be loaded or a traditional high-precision POS system does not need to be loaded, the weight, powerconsumption and cost of the system can be greatly reduced, and the method can be suitable for light and small unmanned aerial vehicle-mounted SAR high-resolution imaging application.

Description

technical field [0001] The present disclosure relates to the field of radar technology, in particular to a motion compensation method for frequency modulation continuous wave SAR based on triangular wave modulation. Background technique [0002] The precise imaging of Synthetic Aperture Radar (SAR) requires that the trajectory of the antenna phase center (Antenna Phase Center, APC) be an ideal uniform linear motion. However, affected by factors such as atmospheric turbulence and platform vibration, the trajectory of the carrier platform is often not an ideal uniform linear motion. The non-ideality of the carrier trajectory leads to the degradation of SAR imaging quality, such as the reduction of resolution, the decrease of signal-to-noise ratio, and the increase of side lobes. Therefore, it is necessary to compensate the negative impact of the non-ideal motion of the carrier aircraft on SAR imaging in the SAR imaging processor, that is, motion compensation processing, in or...

AI Technical Summary

Problems solved by technology

Among them, the SAR motion compensation method based on the motion sensor depends on the high-precision POS system, such as the POSAV510 and POSAV610 series produced by the Canadian company Aplanix. It is used for large-scale manned airborne SAR imaging system, which is difficult to apply to low-cost light and small UAV platform-borne SAR imaging applications

In addition, in recent years, with the development of SAR system technology, its imaging resolution has gradually increased to several centimeters, such as millimeter-wave SAR, laser SAR and other high-resolution imaging systems, the motion measurement accuracy of POS can no longer meet the high-resolution SAR The demand for imaging requires the development of new SAR motion compensation methods

The motion compensation method based on SAR echo data, first of all, needs a large number of prominent point targets in the image to extract the azimuth motion error, so it has a strong dependence on the scene, and when the quality of the special point targets is poor, it will affect the imaging. Second, the method takes image focusing as the ultimate goal, and the phase preservation performance is poor. It is difficult to apply to imaging modes with high phase preservation accuracy such as interferometric SAR and tomographic SAR; finally, the algorithm needs to gradually approach the final value through multiple iterations. Motion error, low efficiency of motion compensation

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