Using transponders with the ERS-1 and TOPEX altimeters to measure orbit altitude to ± 3 cm

Abstract Analysis suggests that, by deploying an active transponder on land beneath a satellite altimeter it should be possible to make a measurement of the height of the satellite as it passes over the transponder with an accuracy equal to or better than that with which the altimeter can measure the range to the sea surface, ± 1 to 3 cm. Early progress in successfully demonstrating the basic altimeter to transponder measurement technique by deploying transponders beneath the ERS-1 satellite is reported, preliminary experiments to assess the technique are briefly described, and some potential applications are identified.