Satellite Altimeter And Scatterometer Sea Surface Echo Simulator Design

The spaceborne Altimeter and Scatterometer (abr. Alt&Scat) are two kinds of very important active microwave remote sensing instruments and have been playing an important role in ocean remote sensing. The ground test and calibration for Alt&Scat is the necessary procedure during the development of the devices, and ocean Return Signal Simulator (RSS) is the key instrument for it. The RSS can provide the simulated ocean return signal for the devices, and realize the simulation on condition of system-on-orbit, which can effectively ensure their normal operation on orbit. The main contents in this dissertation are as follows: To begin with, the Alt&Scat's development history is briefly introduced; the operational principles of the devices and the backscattering model of the ocean return signal are studied in brief. Secondly, the operational principles of the RSS are described in detail; the performance and relevant technique of various kinds of RSS are summarized and analyzed systematically. Based on the above, a new style full signal ocean RSS scheme is designed for Chinese Alt&Scat. A modularized structural designing idea is adopted in the scheme, which results in the high universality of the scheme and the wide application. By employing pulse regeneration technique, full-deramp technique, high-speed DSP technique and all-digital ocean return signal spectrum synthesizing technique, the RSS can fulfill the return signal simulation of both the point target and the sea-surface. Aimed at the scheme, the mathematical simulation model of the signal receiving and transmitting channel is established firstly. Secondly, based on the deep study on the statistical characteristic of the ocean return signal in use of the scientific data received from the Chinese spaceborne Altimeter, a digital synthesis method of ocean return signal simulation is presented. Thirdly, with the tool of Matlab software, the system simulation is conducted, which proves the feasibility and effectivity of the RSS scheme. Finally, the Control & Digital Return Signal Synthesis Unit is designed in this dissertation, and the design verification is conducted. By means of the experiments of the capture&tracking timing, point target response and sea-surface return signal simulation, the system function and technical performance of the ocean RSS are verified all-sidedly.