A Novel Imaging Algorithm with High Range Resolution based on Beidou Signal-Based Passive SAR

Abstract

As is well known, the Bistatic Synthetic Aperture Radar (BSAR) based on Global Navigation Satellite System (GNSS) which relies on its low cost and near real-time global coverage shows an more important character in remote sensing applications. Based on the conventional GNSS system, The novel low orbit augmentation system for Beidou navigation satellite (BDS) can provide higher resolution for the bistatic SAR system from the theoretical range with its wide signal bandwidth. In this paper, A improved high resolution scheme for BDS-BSAR is proposed, it applies the fractional Fourier Transform (FRFT) operator to rotate the range compression signal into the specific fractional domain. Meanwhile, we introduce Teager Kaiser (TK) operator as an equalizer in the preprocessing to compress the pulse in the tuning range, so that the time-varying steering vector becomes a time invariant vector and the wideband GNSS signal becomes a narrowband stationary signal. The proposed method effectively improved the imaging resolution with the irregular imaging grid caused by the bistatic geometry. And also, The proposed effectively mitigate the ambiguity caused by the side-lobes. Lastly, the scheme results demonstrate that the proposed method has more effectiveness and high estimation accuracy than the conventioal approach. At the same time, a high estimation accuracy can be achieved.