ABSTRACT

A distributed multichannel synthetic aperture radar system refers to a multichannel synthetic aperture radar system with channels distributed and installed at different locations on the platform. It is a promising system for high-resolution wide-swath imaging. The channels of the distributed multichannel synthetic aperture radar are sparsely distributed and have long cross-track baselines. The range-variant envelope migration and phase mismatch in the echoes between different channels are introduced by the long cross-track baselines and affect the performance of azimuth signal reconstruction. The sparsity of channels results in the poor correlation of data between channels, so the time-domain cross-correlation method typically used in azimuth multichannel synthetic aperture radar cannot be used in distributed multichannel synthetic aperture radar to estimate channel phase error directly. In this paper, the gain-phase error, sampling time delay and slant range difference introduced by cross-track baselines are modelled uniformly as channel mismatches. Firstly, a two-step channel mismatch estimation and compensation method for distributed multichannel synthetic aperture radar is proposed. Secondly, a range-variant envelope migration compensation method based on the chirp scaling principle is given. Thirdly, this paper also presents the processing of data rearrangement based on the distribution of spatial sampling points to make the time-domain cross-correlation method suitable for distributed multichannel synthetic aperture radar. Point target simulation and scene simulation are provided to show the effectiveness of the proposed methods.

摘要

分布式多通道合成孔径雷达系统是指通道分布安装在平台不同位置的多通道合成孔径雷达系统。它是一种很有前途的高分辨率宽幅成像系统。分布式多通道合成孔径雷达的通道分布稀疏，交叉轨迹基线长。长跨航迹基线引入了不同通道之间回波中的距离变化包络偏移和相位失配，并影响方位角信号重建的性能。通道稀疏导致通道间数据相关性差，因此，通常用于方位多通道合成孔径雷达的时域互相关方法不能用于分布式多通道合成孔径雷达直接估计通道相位误差。本文将跨轨基线引入的增益相位误差、采样时间延迟和斜距差统一建模为通道失配。首先，提出了一种分布式多通道合成孔径雷达的两步通道失配估计与补偿方法。其次，给出了一种基于线性调频缩放原理的范围变化包络偏移补偿方法。第三，本文还提出了基于空间采样点分布的数据重排处理，使时域互相关方法适用于分布式多通道合成孔径雷达。提供了点目标模拟和场景模拟来展示所提出方法的有效性。