Research On Fast Link Establishment Technology Based On HF Full Band Digital Channelized Receiver

HF communication is widely used in military,emergency and disaster relief fields because of its high flexibility,strong resistance and long communication transmission distance.The traditional HF communication system relies heavily on the preset set of point-to-point operating frequencies when establishing link,and the separation of frequency selection,detection,link establishment and communication results in the HF communication link establishment mechanism is not flexible enough,which has the problems of low frequency selection accuracy,low link establishment efficiency and low resource utilization.In this thesis,a fast link establishment scheme based on HF full band digital channelized receiver is presented,which improves the connectivity and stability of HF communication link,and maximizes the efficiency of spectral resources.The specific research contents are as follows:1.In view of the problems that most of the existing HF communication equipment do not have full band reception capacity,and a small number of equipment with full band receiving capacity have the disadvantages of high resource consumption and high cost,based on the two-stage polyphase filter DFT channelized cascade structure,a HF digital channelization structure with two-stage channelization of 1024 channels 24 k Hz subchannels is designed in this thesis.HF full band reception can be achieved by using a FPGA processing board,which reduces engineering costs and implementation difficulties,and improves system resource intensiveness.2.For the traditional HF link establishment system,the separation of detection and link establishment does not suit the problem of high dynamic HF channel very well.In this thesis,a fast link establishment scheme based on HF full band reception is proposed by using the link establishment strategy of establishing link immediately after detecting.Combining historical data results with active detection methods enables fast and robust connectivity in complex electromagnetic environments.At the same time,a communication detection integrated sensing waveform based on Linear Frequency Modulated signal is designed to solve the time redundancy caused by waveform switching.The simulation results show that the channelization structure can enhance the receiving performance of the link establishment system.The fast link establishment scheme designed in this thesis is superior to the traditional link establishment scheme in the linking success rate.3.In view of the traditional HF communication over-dependence on long-term prediction model,without considering the accidental factors of actual communication,this thesis studies the real-time channel quality assessment method based on pulse compression characteristics of LFM signals,and describes the characteristics of HF channel differentiation.The estimation accuracy of Doppler frequency offset is improved by using frequency offset estimation method based on correlation heuristics,and the signal-to-noise ratio estimation method with frequency offset estimation error is given.Finally,a scattering function channel parameter estimation method which can characterize the two-dimensional time-frequency characteristics of the channel is given.The simulation results show that the parameter estimation method has higher estimation accuracy,the frequency offset estimation method has better anti-noise ability,the signal-to-noise ratio estimation method can solve the problem of frequency offset estimation error,and the channelization structure has some influence on the accuracy of channel parameter estimation method,but it can be corrected and eliminated.On the basis of the above link establishment scheme design,each module of HF digital channelized receiver is implemented on the platform of FPGA.Finally,combined with the existing equipment and test site in the laboratory,the feasibility of the fast link establishment scheme proposed in this thesis is verified under the real HF communication environment.