Echo signal quality analysis during HY-2A radar altimeter calibration campaign using reconstructive transponder

A reconstructive transponder has been utilized for the in-orbit calibration campaign of the HY-2A radar altimeter since March, 2012. The precision of final calibration result is influenced by echo signal´s quality in the HY-2A altimeter´s range window. Echo signal dwell time is analyzed considering its influence on signal quality and its fluctuation. Comparing with the length of the HY-2A altimeter´s range window, the radial component of orbit prediction error is large. The tracking mechanism of the reconstructive transponder utilizes some incoming signal samples without sending echo signals to establish stable tracking. Large radial orbit error and tracking mechanism of the reconstructive transponder are two main factors that limit the precision of the final range calibration result. Finally, approaches for increasing echo signal dwell time are proposed.