slide 12

The raw SAR data has low resolutions due to certain factors. The range resolution depends on the pulse width and the speed of light. If the distance between two points is shorter than this resolution, their return signals get mixed and cannot be separated. The azimuth resolution is affected by the wavelength, antenna length, and height of the SAR platform. If neighboring footprints are too close, they cannot be distinguished. The range and azimuth resolutions in the raw SAR data are close. We will talk about how to increase both resolutions later, and you will know the length of SENSATIC aperture radar results from the technique used to increase azimuth resolution. Before talking about those, I would like to introduce you why the raw resolutions are low. The resolution means the return signals from two neighboring points are separable. The range resolution is half of the light speed times pulse width. If the distance between two points P1 and P2 are shorter than this distance, their return signals are mixed and cannot be separated. I will talk about it later. The azimuth resolution is dependent on the wavelength, antenna length, and the height of the SAR platform. In the figure below, if the neighboring footprints are closer to this distance, the footprints cannot be distinguished.