Design of the SEASAT-A Radar Altimeter

A third generation satellite radar altimeter to be flown on the SEASAT-A mission in 1978 is described. Building on SKYLAB and GEOS-C experience, a design has evolved that will allow a long-term goal of 10-cm altimetry to be realized. While dependent on recent developments in surface acoustic-wave device technology, the design in all other respects presents no major difficulty. A linear FM/full-deramp waveform and processing technique allows fine range tracking to be done in the frequency domain. A digital filter bank will provide 60 contiguous samples of the ocean return waveform with 3.125-ns resolution. An adaptive tracker built around a microprocessor will operate on the waveform samples to implement the basic height tracking function, adjusting its parameters in response to sensed waveheight.