A general two-dimensional spectrum based on polynomial range model for medium-earth-orbit Synthetic Aperture Radar signal processing

The kth-order polynomial range model (PRM) for Medium-Earth-Orbit (MEO) Synthetic Aperture Radar (SAR) signal processing is proposed, analyzed, and verified in this paper. The coefficients of the PRM are calculated according to the relative state vectors between the satellite and the given target on earth, which implies power series expansion around the beam center crossing time. In addition, the relevant two-dimensional spectrum is deduced out as well by using the principle of stationary phase (POSP) and the series reversion approximation. The accuracy of this spectrum is flexible and limited both by the order of the PRM and the order of the spectrum in an expanded form. Therefore, the PRM-based spectrum is general for MEO SAR with any azimuth resolution at any orbit height.

I. Introduction

Synthetic aperture radar (SAR) makes an image of the surface of the earth by transmitting and receiving successive pulses and then coherently processing them^[1] Since 1978, several spaceborne SAR systems have been launched and applied successfully in remote sensing areas. The rapid progress in SAR world profits from the development of digital signal processing. Meanwhile, the SAR imaging principle and the SAR formation technique promotes the signal processing methods as well^[2].