Synthetic Aperture Technology-based High-precision Radar Altimeter Technology Research

In order to meet the needs of the oceanography observation and the gravitational field study as well as the sea ice, ice sheet study and so on, the synthetic aperture technology was introduced into the conventional radar altimeter, thus formed a new generation of radar altimeter. This dissertation is an integrated research of this new type of radar altimeter, which especially focuses on the following themes:1. Theory of Synthetic Aperture Technology in Radar Altimeter. It is known that radar altimeter is of high precision, but the application of the synthetic aperture technology in radar altimeter will cause some problems in obtaining the high precision for un-fixed range between radar and targets. The author will first study these problems and their corresponding solution.2. The mean echo wave model study. As a result of high accuracy range measurement requirements for altimeter, recovery algorithm depends on the mean echo wave model. The mean echo wave model is a basis of the radar altimeter. The author in the dissertation will establish the mean echo wave model and then continue the analysis of the echo characteristic based on the model.3. Verification of the Echo Wave model by simulating the echo wave of sea surface. In view of the lack of the experimental data, for the examination of the mean echo wave model, the author has used the empirical ocean wave spectra to simulate three dimensional sea level and its radar echo. The results indicate that the mean echo wave model is consistent with simulation echo.4. Processing technology of echo wave. The altimeter generally retrieves the range information and other related parameters from the echo wave, echo signal processing technology therefore is of importance. Because of the application of the synthetic aperture technology, the new radar altimeter has a different work mode with that of the conventional altimeter; therefore, its echo signal processing technology has its own characteristics. The author has also conducted the research.5. System design. On the basis of above-mentioned researches, a simple radar altimeter of the new type was designed and the mean echo wave model, the echo characteristics analysis and the echo signal processing technology as well as the functional examination have been carried out on the radar altimeter system.