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针对电离层对星载SAR线性调频信号影响与频率有关的特点,结合正负调频率的线性调频信号受电离层影响会出现脉冲信号的压缩和展宽现象,提出了一种基于星载SAR编码有源定标器的电离层TEC测量方法.利用编码有源定标器可以实现调频率反向的功能,通过分析调频率反向和不反向两种信号的相位差以及脉压后的位移差实现电离层TEC的精确测量,该方法不依赖于SAR与有源定标器之间的距离以及SAR发射信号的相位,减小了电离层TEC测量的误差因素,提高了电离层TEC的测量精度.针对BIOMASS,TerraSAR-L以及HJ1C三部不同频段的SAR系统进行了仿真分析,仿真分析结果与理论计算一致,证明了该方法的有效性.
According to the ionospheric characteristics of spaceborne SAR linear frequency modulation signals and frequency-dependent, combined with positive and negative frequency modulation of the chirp signals affected by ionospheric pulse compression and broadening phenomenon, a satellite-based SAR coding Source scaler ionospheric TEC measurement method. The use of active encoding scaler can be achieved reverse frequency function, through the analysis of the frequency of the reverse and non-inverted two kinds of signal phase difference and pulse pressure difference after the displacement Realizing accurate measurement of ionospheric TEC, this method does not depend on the distance between SAR and active scaler and the phase of SAR emission signal, which reduces the error factor of ionospheric TEC measurement and improves the measurement accuracy of ionospheric TEC The simulation and analysis of the three SAR systems with different frequency bands of BIOMASS, TerraSAR-L and HJ1C are carried out. The results of the simulation are consistent with the theoretical calculations, which proves the effectiveness of the proposed method.