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Surface Roughness Measurements by using Low-Resolution FM-CW Radar Altimeters

When a radar altimeter is used over a rough ground surface, a noise component is added to the output signal. The mean deviation of the noise mainly depends on the range spread of the reflectors located within the antenna beam. The close relationship between noise and range spread can be used to estimate the height of surface roughnesses by low-resolution radar altimetry. Experimental results compare favorably with theoretical predictions.