Error Extraction and Compensation Method of Calibration Signal

By broadcasting a linear frequency modulation signal (LFM) with a large temporal width and bandwidth, the airborne spaceborne synthetic aperture radar (SAR) achieves high resolution in the range. The chirp signal flowing across the transmitting and receiving links has certain amplitude and phase defects since the actual system is not a perfect system. The effect of pulse compression will be substantially influenced by non-linear phase inaccuracy. System calibration can extract nonlinear errors, perform polynomial fitting on the retrieved errors, and apply amplitude and phase correction to the broadcast signal, thereby improving the chirp signal's pulse compression impact.

I. Introduction

Synthetic aperture radar has the working characteristics of all-weather and all-time. It can obtain effective radar images and application products at all levels in complex working environment. It is widely used in the field of national economy. In the continuous development of SAR imaging, high-resolution imaging is a development direction that has attracted much attention. With the increasingly diversified requirements, radar system is developing beyond the trend of reconfigurable bandwidth, large bandwidth, multi-mode and multi-function integration. Affected by the characteristics of electronic components, the traditional radar system has development bottlenecks such as limited bandwidth and vulnerable to electromagnetic interference. Therefore, how to use the signal with large time width and large bandwidth for high-quality signal processing in the radar system is a hot research direction of many scientific researchers. LFM signal is the most widely used large time broadband wide product signal in SAR system. Good range resolution can be obtained by pulse compression. Obtaining high-quality LFM signal is the most basic element of high-resolution imaging [1]-[5].