Optical Wirless Links For Intra-Satellite Communication: Link Budge Analysis And Conversion Interface Technology

Optical Wirless Links for intra-Satellite communication (OWLS) use the infrared light instead of the traditional data cables as an information carrier to transmit data between the payloads which are fixed within the satellite with the complex structure and the small margin. In the space environment, the benefits of replacing standard data wires and connectors with wireless systems are:mass reduction, low power consumption, wide bandwidth, the lack of Electro-Magnetic Interference/Compatibility (EMI/EMC), flexibility, and simplification of the Assembly, Integration and Tests phases (AIT). In recent years, OWLS becomes a hot topic of research worldwide. Because of the Specificity of the space environment and intra-satellite environments, substituting cables and connectors with optical links inside a spaceborne platform represents some technical challenges, such as the rad-hard components, the combination optical wireless and wired network protocols et al. This paper studies two aspects:the method of link budget and the bus interface converter circuit design.Firstly, various methods of link budget analysis which used at indoor environments and intra-satellite environments and various surface reflectance model are presented, and then Monte Calo ray-trace and bidirectional scattering distribution function (BSDF),which is in TracePro software, is used to analyse the performance of optical channels for intra-satellite environments. This software can analyse light distribution and impulse response. A complete method of link budget is obtained, and proposed method to improve link budget.Secondly, various communication bus which used in the satellite is presetatoned, and SPI bus which is used intra-satellite is analysed and investigated. The knowledge of FPGA design is also described. The design of conversion interface which is used between SPI bus and optical wireless transceiver by Verilog HDL is presented. And Modelsim software is emploied to simulate in the chapter four. The correctness of logic is verified by using experimental link measurement which is constituted by Actel FPGA and STC12LE5A60S2 MCU with SPI bus.Finally, the work of research is summarized, and further activities is discussed.