High squint helicopter-borne terahertz ViSAR vibration compensation imaging algorithm
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摘要:
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。
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关键词:
- 太赫兹 /
- 大斜视 /
- 视频合成孔径雷达(ViSAR) /
- 平台振动补偿 /
- 多普勒Keystone变换
Abstract: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 characteristics 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 Keystone 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 effectiveness of the proposed algorithm.
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图 3 斜视太赫兹ViSAR振动补偿成像算法流程
Figure 3. Flow of squint terahertz ViSAR vibration compensation imaging algorithm
表 1 仿真参数
Table 1. Simulation parameters
参数 数值 载波频率f0/GHz 200 场景中心斜距rC/km 2 直升机飞行速度v/(m·s-1) 50 脉冲重复频率PRF/kHz 3 脉冲带宽Tp/GHz 1.5 距离向采样频率Fs/GHz 1.8 
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