Research On Technologies Of Non-cooperative Burst Signal Demodulation Based On Detection Information

Burst communication has emerged as a promising field in military communication,due to its excellent anti-jamming performance and high concealment.For example,burst communication with middle or high frequency often applied in submarine communication system and Link-16 tactical data link.In communication countermeasure,as a method to extract information,communication reconnaissance necessitate intercepting the enemy signal to complete the pattern recognition,the parameter estimation,and then parse the signal data information and provide information support for the partners,which is also conductive to the subsequent interference.Without enough prior information,the non-cooperative burst signal is extremely difficult to demodulate by receiver.In this paper,the burst single PSK signal with short time and narrow space focus,in order to complete the signal synchronization and accurate demodulation of signal based on detection information by receiver.On the basis of constructing the model of the non-cooperative burst signal demodulation system,this paper focuses on the carrier synchronization and timing synchronization technology research of non-cooperative burst PSK signal,in order to complete the symbol judgment accurately for the coherent demodulation.Specific contents as follows:Firstly,the basic theory of synchronization and parameter estimation criterion are systematically studied to establish the mathematical model for the received signal,and the processing flow of the non-cooperative burst signal demodulation system is given.Secondly,to solve the problem of the carrier synchronization,two non-data-aided carrier frequency offset estimation algorithms based on signal auto-correlation and based on signal phase are discussed.Through quantitative performance analysis of the carrier frequency offset estimation,the mean square error,the unbiased estimation range and the jitter of the parameter estimation can be obtained.It is verified that the estimation algorithm can achieve excellent performance in the absence of prior information.To balance the requirements of real-time and estimation accuracy,a joint carrier recover algorithm based on signal phase difference and loop processing is proposed.The non-data-aided algorithm based on signal phase difference is put forward to realize the coarse estimation of carrier frequency offset firstly,and then the loop processing accurately estimate the carrier phase offset.Simulation results validate that the proposed algorithm can achieve the carrier synchronization with the high accuracy and brilliant real-time performance.Thirdly,the algorithms of two parts of the timing error estimation and timing error correction are used to timing synchronization of the burst signal.As for timing error estimation algorithms,the nonlinear transformation algorithm and time-domain synchronization algorithm based on maximum likelihood criterion are mainly studied.These algorithms belong to the forward open-loop algorithms.The simulation results show that the algorithms have splendid estimation performance and real-time performance,but the computation budget and complexity of the algorithms are high.After estimating the timing error,the interpolation filter technique applies to realize the timing error correction,and the interpolation filter is implemented by Farrow structure.Finally,an overall demodulation program based on detection information for non-cooperative burst PSK signal is presented,and the key technologies of each module is elaborated,and the influence of the synchronization error on the demodulation is analyzed.