大斜视直升机载太赫兹ViSAR振动补偿成像算法

High squint helicopter-borne terahertz ViSAR vibration compensation imaging algorithm

太赫兹视频合成孔径雷达(ViSAR)载波波长短,直升机载平台的微小高频振动将引起回波信号相位的显著变化,进而严重恶化ViSAR的成像性能。本文在建立斜视ViSAR平台振动成像几何模型的基础上,提出了大斜视模式下的振动相位误差补偿成像算法。该算法结合运动补偿原理,将斜视成像侧视化处理,然后采用改进的多普勒Keystone变换方法在二维频域校正由平台振动引起的距离单元徙动,最终在距离多普勒域实现振动相位误差补偿。仿真结果验证了该算法的有效性。

With advantages such as fast imaging frame rate, high resolutions and penetration through dust and smoke, video synthetic aperture radar （ViSAR） has a broad application prospect. But for ViSAR that works in terahertz carrier frequency, helicopter platform＇ s tiny high frequency vibration will cause obvious changes in echo phase and degrade the imaging quality. According to helicopter platform＇ s vibration charac- teristics and based on the squint platform vibration imaging geometry model, this paper proposes a terahertz ViSAR vibration phase error compensation imaging algorithm in high squint mode. First, the squint imaging is equivalent to side-looking imaging based on motion compensation principle, and then modified Doppler Key- stone transform is performed to correct the range cell migration induced by platform vibration in 2D frequency domain. Finally, the analytic expression of vibration phase error is gained in range-Doppler domain and the phase error compensation is achieved via parametric autofocus method. Simulation results verify the effective- ness of the proposed algorithm.