Integrated System of Side-looking InSAR Altimeter and Nadir-looking Altimeter Based on Signal Coding

Abstract

Satellite radar altimeter is an important means to obtain global marine dynamic environmental factors such as sea surface height, significant wave height and sea surface wind speed. Based on the sparse characteristics of the nadir echo, this paper proposes the integrated system design of the nadir-looking altimeter and the side-looking interferometric synthetic aperture radar (InSAR) altimeter by signal coding for the first time. The system transmits the coded signal pulse sequence periodically and selects the appropriate pulse repetition frequency (PRF), so that the echo from nadir and side area are received at the same time, but their corresponding radar transmission signal waveforms are different; The transmitted signal corresponding to the nadir echo signal is used as the matched filter function to compress the received echo signal, and the bottom elevation is inversed by tracking and extracting the nadir echo signal, so as to realize the function of nadir-looking altimeter; Then, the transmitted signal corresponding to the nadir echo signal is used as the anti-matching filter function to carry out the anti-matching filter processing on the signal that removes the nadir echo signal, and then the transmitted signal corresponding to the side echo signal is used as the matching filter function to carry out range compression, and the subsequent azimuth compression and subsequent interferometric processing are carried out to realize the function of interferometric synthetic aperture radar side-looking altimeter. The system design method can provide important support for the development of Spaceborne Radar Altimeter System in China in the future.