Altimeter designs: SEASAT‐1 and future missions

Abstract

With the launch of SEASAT‐1 in June 1978, an altimeter of improved performance joined GEOS‐3, which had been operational for three years. The advances in design that resulted in <10 cm rms height precision are discussed and some early onorbit performance results presented. In addition to improved resolution and a higher pulse rate, both of which acted to reduce height noise, the SEASAT‐1 altimeter incorporated a microcomputer which allowed flexibility in choice of tracker characteristics and provided for on‐board computation of significant waveheight. Under consideration for future missions are a multi‐beam capability to increase the swath coverage, the primary thrust being more rapid development of current maps, and an uplink programming capability for the microcomputer to facilitate on‐board processing in a way which permits post‐launch algorithm modification. Addition of a rainfall detection mode to the altimeter has also been proposed, and consideration has been given to the reliability improvements needed to support a three‐year mission.