相机的自动对焦感应点需要一些影像细节来确定相位差，光线不足或者物体细节不足都会导致聚焦困难。
The camera's AF sensors require some details in the image to determine the phase difference. It's harder for the camera to find focus when the light is dim or there is little subject detail.
三大同步中，相位同步误差直接影响SAR复影像的相位误差，从而影响系统的高程测量精度。
The error of phase synchronization among the three synchronizations will affect the phase error of SAR SLC image directly, and influence the elevation measurement precision sequentially.
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