Research On Optical Wireless CAN Bus For Intra-Satellite Communications

Optical wireless links intra-satellite communications (OWLS) is a new technology for realizing the data transmission in satellite, for application as internal satellite environment with narrow space, numerous equipments and wires. The tradition cable was substituted by infrared light in physical layer avoiding impact on upper protocol of satellite communication. Optical wireless Controller Area Network (CAN) bus for intra-satellite communications (OWCAN) is an important branch of OWLS. It takes CAN bus which was widely used in satellite as transmission foundation. By replacing the physical layer of CAN bus, infrared light was used instead of cable wires as transmission medium and has no effect on higher level protocol.OWCAN not only has normal advantages of OWLS such as lighten satellite load, install flexibly, electromagnetic compatibility (EMC) immunity, etc. but also has its own characteristics. There are many advantages of CAN bus, such as higher transmission rate, good reliability, excellent anti-interference capability, various testing methods, etc. Because of all the merits mentioned above, OWCAN becomes the key topic in the research of OWLS. This paper focus on OWCAN research, mainly investigates the design of optical wireless CAN bus module based on CAN bus protocol and related electronic components.First, the feasibility of utilize infrared light as CAN bus physical layer is analyzed. By learning the protocol of CAN bus, the problems need to be considered is found out. These problems mainly include bit definition, collision detection, monitoring and the arbitration. By learning from8051microcontroller and SJA1000CAN controller, the software and hardware of optical wireless CAN bus module have been designed. The software is programmed by C language. The hardware mainly includes the encoder and decoder of None Return Zero (NRZ) and Return Zero code (RZ), the interface circuit between module and optical transceiver.Next, the discussion is presented when the module is implicated in spacecraft. The circuit design and the choice of electronic components are introduced. After that, in order to verify the rationality of the module design and optical wireless CAN bus communications in the mock-up of satellite, the experimental communication links are constructed.Finally, the paper has been summarized and further research work is discussed.