Digital module design of a satellite rain-compatible radar altimeter

Satellite radar altimeters play an independent role in ocean remote sensing, while the authors exploited their potential in rain measurement. This paper designs the digital system of the rain mode in an altimeter. In rain mode the altimeter receives the ocean and rain echoes simultaneously, so it can retrieve the rain layer profile without losing surface topography information. An adaptive IF-digital I/Q demodulator is designed, and all of its components are considered in turn. Afterwards the algorithm of an ocean-rain compatible processor is designed to switch the altimeter in various operate modes.