The mean echo model and data process of SAR altimeter

This paper is concerned with the theoretical model for SAR altimeter or Delay-Doppler radar altimeter. Work with this aim, first, the data process of the SAR altimeter is introduced and some assumptions of SAR altimeter systems are introduced. And this result in that the mean echo model of SAR altimeter could expressed as three terms convolution as that of conventional radar altimeter. Second, the sub-fan-beam pattern formed by along track signal process is analyzed and approximated with one simplified Gaussian expression. Third, the SAR altimeter measurement geometry is described and the mean echo model in common sense is described with parameters echo delay, sea wave height, scatter coefficients and radar antenna pointing angle. Some applications of these results are presented at the last section, include some features of mean echo model and proposal for future SAR altimeter system.