Key Technologies Esearch And Erification Of Pace-ground Dynamic Multi-nodes Omnidirectional Data Link

Space-ground dynamic multi-nodes omnidirectional data link is a distributed communication system achieving multi-nodes information distribution and situational awareness. Precise time synchronization and data transmission which are provided by the data link are used in these nodes to response quickly and process signal collaborativly. For the purpose of supporting platform high dynamic, high bandwidth, low latency and long-distance transmission of information, main tasks are as follows:Firstly, the requirements and physical layer transmission scheme of the system are analysised. Scenarios, modes of work, Transmission performance and other functional requirements of Space-ground dynamic multi-node omnidirectional data link are discussed. Data transmission channel which supports bit error rate less than 10-6 in 20 km at 6Mbps and node discovering channel which supports bit error rate less than 10-6 in 100 km at 500 kbps are disigned.Secondly, key technology of the physical layer is demonstrated. For issues that AD/DA sampling rate is higher than the oscillator clock frequency of the hardware platform, a digital multiphase-sampling-polyphase filter structure is implemented, reaching a result that 1000 Msps signal is synthesized finally by four-phase sampling rate of 250 Msps sampling rate signal. Concerning about precision accuracy is limited by hardware platform of the oscillator clock frequency, a polyphase matched filter at 250 MHz clock frequency of the local oscillator with which high-precision time accuracy can reach 1ns is realized.Thirdly, program and performance testing are devised. Key technical signal transmitter and the signal at the receiving end are achieved respectively based on Xilinx FPGA hardware platform, then network node discovery and rapid testing verifys network node time less than 5s, global time synchronization accuracy less than 4ns; point and bit error rate testing of space remote node multi-service transport testing verifys node transmission bit error rate is less than the order of 10-6, meeting the design requirements.This paper designs a data transmission scheme and a high-precision time capture technology which can be applied to multi-node data co-processing chain with engineering significance.