| The Link 16 tactical data link is the most widely used universal data link currently in service by the US military and NATO nations.In the current and future wars,the data link will become an important part of the joint operations of the three armed forces.In a complex battlefield environment,ensuring the reliability and effectiveness of tactical data exchange is critical to obtaining war initiative.In this context,research on the key technologies of the physical layer of the Link 16 data link has certain significance for the construction of our army's informatization.Based on the existing research,this thesis further studies the key technologies of Link 16 physical layer data transmission.The specific work is as follows:?1?Research on frequency hopping technology in Link 16 network.The research of frequency hopping technology includes two aspects,frequency hopping pattern and frequency hopping synchronization.Based on the characteristics of frequency hopping patterns in Link 16 network,a method is proposed that constructing high uniformity and wide interval frequency hopping patterns based on L-G model in this thesis,which is used in the future research on the detection and interference of Link 16 to use this frequency hopping pattern construction method to generate signals with Link 16 characteristics..At the same time,two types of frequency hopping synchronization schemes are designed,namely a single LO with low hardware implementation complexity serial synchronization scheme and multi-LO cooperative parallel synchronization scheme with high synchronization probability.Simulations show that the proposed frequency hopping pattern construction method has excellent performance,and the two frequency hopping synchronization schemes also have good synchronization performance in a low signal-to-noise ratio environment.?2?Research on receiving baseband processing algorithm in JU.The research of baseband processing algorithms includes four aspects,namely slot acquisition,slot time synchronization,data pulse carrier synchronization,and data pulse demodulation and despreading.First,the existing signal detection research results are simulated and analyzed.Then,for the Link 16 signal scene,an MSK signal detection algorithm based on continuous differential decision correlation operations is proposed,and the corresponding pulse capture strategy is given.At the same time,based on the existing frame synchronization research conclusions,a double correlation frame synchronization algorithm for pulsed signals is deduced,and based on this algorithm,two improved oversampling timing synchronization algorithms are obtained.In terms of signal demodulation and despreading,a joint ML-CCSK signal demodulation and despreading algorithm is proposed to address the shortcomings of the independent demodulation and despreading scheme,which can further approximate the spreading gain.Finally,a set of receiving baseband signal processing algorithms is summarized.Simulation results show that when the signal-to-noise ratio is not lower than-3.46dB,the symbol error rate of the algorithm is not higher than 10-3,which meets JTIDS/MIDS sensitivity requirements.?3?Hardware implementation and test of receiving baseband algorithm.First,the AD9361,FPGA and DSP are used to implement the baseband processing algorithm,and the implementation process of the algorithm on the verification platform is given.Then we use the signal source to generate Link 16 RF signals in different channel environments and transmit them to the hardware implementation platform to test the symbol error rate.The test results show that the sensitivity of the receiver can reach-98.8dBm,which meets the sensitivity requirements of JTIDS/MIDS in all communication modes. |
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