多TDICCD拼接遥感相机成像串扰分析与抑制

Imaging Crosstalk Analyzing and Suppressing for Multi-TDICCD Mosaic Remote Sensing Camera

为了解决多时间延迟积分(TDI)电荷耦合器件(CCD)拼接遥感相机不同CCD通道间的成像串扰问题,提高相机信噪比(SNR)和成像质量,利用周期信号的傅里叶级数分析法推导成像串扰的数学模型。根据理论分析结果提出多TDICCD成像串扰的根本原因是CCD工作不同步造成TDICCD成像电路电源的地平面高频扰动影响到了相邻通道CCD有效视频信号的采集。从工程研制实际出发,采取CCD通道之间的工作电源隔离以及共用统一的系统时钟等措施对多TDICCD成像电路系统进行改进,抑制成像串扰的发生。对改进后的多TDICCD成像电路系统进行成像和信噪比测试。实验结果表明,采取的措施有效地去除了CCD通道间成像串扰条纹,相机信噪比得到了显著的提高,在相机入瞳辐亮度为42.6W/(m2·Sr)的条件下,相机信噪比提高18.85dB,达到了50.42dB,且外场成像质量高,满足实际工程的需求。

In order to solve the imaging crosstalk between charge coupled device （CCD） channels and improve the signal-to-noise ratio （SNR） and imaging quality of multi time delay integration （TDI） charge coupled device mosaic remote sensing camera, a mathematical model of imaging crosstalk is established based on Fourier series analysis of the periodic signal. According to the results of mathematical analysis, the root cause of multi-TDICCD imaging crosstalk between different channels is proposed to be the unsynchronized TDICCD imaging circuit working, which causes high-frequency disturbance on the power ground plane and eventually affects the effective video signals acquisition of neighboring TDICCD. Referring to practical project, isolated CCD power supply, shared unified system clock and other methods are adopted to optimize multi-TDICCD imaging circuit system to suppress the occurrence of imaging crosstalk. The imaging quality and SNR are tested after improvement. Experimental results indicate that the adopted methods which can prevent the occurrence on imaging crosstalk between different CCD channels are effective, and the SNR is improved significantly. When the radiance is 42.6 W/（m2 -St）, the camera SNR increases 18.85 dB, reaching to 50.42 dB. The image quality of outside scene imaging is also improved significantly, which can meet the requirements of practical engineering of TDICCD remote sensing camera.