Research On Inter-satellite/Intra-satellite Communication Technology

Operationally responsive space technology was an important developmentdirection of space technology. Inter-satellite/intra-satellite communication systemis an important part of the operationally responsive space satellite platform. Thewired way of point-to-point or bus was usually used in traditional intra-satellitecommunication commonly. But this way was not able to realize plug-and-playproach, and was not suited to the rapid integration and quick testing to realize therapid responsive. In this paper, intra-satellite communication system based on thewireless network was put forward. For the special property of intra-satellitecommunication system, the system structure, electromagnetic compatibility and thesoftware protocol were researched in this paper. For inter-satellite communicationand the formation flying, variable rate communication was proposed, and wassimulated and experimented.Firstly, intra-satellite communication system architecture based on the wirelessnetwork was put forward. For requirements of single machine/components, thearchitecture concluded wireless communication unit and special module unit. Theinformation exchange between special module units was realized through wirelesscommunication unit. In order to improve the intra-satellite communication systemarchitecture, multipath, occlusion and so on, main performance and technical indexwith different communication system were deeply studied. FSK/GFSK modulationand demodulation technique was taken. The theoretical model of wirelesscommunication unit was established. SOC and RFIC were as core component tocompose the wireless communication basic unit. The rationality and feasibility ofintra-satellite communication system architecture was verified, through the in-orbittest. This result provides a theoretical basis for the wireless communicationapplication.For the occlusion and multipath problems of wireless communications, a newmethod of multi-loop antenna RF coupling communication was put forward. Anear-field RF communication model based on the theory of antenna design wasbuilt. The simulation and experimental results shows that this method can achievereliable RF communications. At the same time, the problem of occlusion andmultipath were solved. The mechanism of intra-satellite/out-satellite wirelesscommunication under electromagnetic environment was also researched. Theconclusion that intra-satellite communication and external RF signal was notaffected each other. This result was verified correctly by actual wireless communication unit. The characteristic of intra-satellite communication providestheoretical support for communication channels and information path design.Based on intra-satellite communication system architecture, a wireless networkcommunication protocol with dynamic time slot allocation was proposed forPlug-and-Play demand. The communication protocol used the work of themaster-slave. The lower computer node new entrants to the system request responsetime slot according to the network. The host computer node assigns response timeslot for the lower computer according to the working timing of network nodes.Then complete unified control of stand-alone components and plug-and-play ofstand-alone components. Through the simulation and in-orbit experimental, thewireless network communication protocols based on dynamic slot allocation cansolve the collision problem, and can achieve accuracy real-time requirement.Protocol allowed nodes joining and withdrawing from the network freely to realizeplug-and-play. The method of wireless inter-satellite communication technologyhad been verified by in-orbit test through SY-3.Because the status is short-distance between satellites, a great amount of datafor exchange during the satellite formation flying task. Otherwise, the status isopposite. According to the communication link equation, under the same conditionsin the transmit power and SNR. Put forward a method of inter-satellite variable ratecommunication. So as to achieve exchanging between the loss of communicationrate and communication distance loss. Accumulation of the video signal detectionmethod was to solve the difficult problem of RF signal detection andsynchronization. Using a common RF channel to solve the problem of variable ratecommunication, and simplify system design. The method of variable ratecommunication had been verified by in-orbit test through SY-3. The variable ratecommunication can reach from400bps to250kbps formation exchanging.