Research On High Dynamic Frequency Fast Locking Technology

In recent years,with the advancement of science and technology,communication systems under high dynamic situations such as aviation,aerospace,and satellites have developed faster and faster.The design of communication receivers under high dynamic situations has become a research hotspot.In a highly dynamic situation,the high-speed movement of the two communication parties will cause the signal to form a Doppler effect.It produces a frequency offset and a high-order frequency offset change rate,causes the phase of the signal to rotate and the signal cannot be demodulated normally.In the face of the new characteristics of communication systems in high dynamic situations,the relevant traditional carrier technology is no longer applicable.Therefore,it is of great practical significance to shift the focus of exploration to the research of frequency fast lock technology based on high dynamic scenarios.This article mainly focuses on the application of time-domain-related frequency estimation algorithms in high dynamic scenarios under data-assisted methods,mainly including:1?The second chapter introduces the traditional carrier synchronization technology,which is mainly divided into two types: closed-loop and open-loop.which is mainly divided into two types: closed-loop and open-loop.First of all,this chapter introduces the basic principle of phase-locked loop in closed-loop mode,and analyzes the key parameters of its design.Then it introduces the data-assisted FFT frequency estimation algorithm in the open-loop mode,deduces its estimation principle,and proposes related improvement methods for the accuracy of FFT.Finally,I focused on introducing dataassisted time-domain estimation algorithms: Kay algorithm,Fitz algorithm,L&R algorithm,M&M algorithm,and cross-correlation algorithm.The parameter estimation formulas of these algorithms are deduced,and the estimation accuracy,estimation range,and computational complexity of several algorithms are analyzed and compared,and the corresponding application scenarios of several algorithms are summarized.2?The third chapter introduces the carrier synchronization acquisition technology in high dynamic situation.First of all,in view of the spectrum broadening problem of FFT algorithm in high dynamic environment,this paper introduces the delay autocorrelation algorithm based on FFT,simulates and analyzes its capture performance,and summarizes the advantages and disadvantages of the algorithm.Then the parameter estimation formulas of several time domain estimation algorithms under high dynamic situation are derived and the estimation accuracy and estimation range of these algorithms are analyzed and compared.Finally,aiming at the time domain estimation algorithm under high dynamic conditions,a carrier acquisition algorithm based on pilot assisted is proposed,and the normalized mean square error of frequency offset and rate of change of frequency offset after capture is simulated and analyzed,which proves that it meets the requirements of tracking part.3?The fourth chapter introduces the carrier synchronization tracking technology in high dynamic situation.Firstly,the carrier tracking technology based on frequency-locked loop assisted phase-locked loop is introduced.On the one hand,the frequency discriminator and phase discriminator of the loop are determined according to the tracking frequency and phase range,On the other hand,the loop bandwidth of the two loops is determined according to the thresholds of the dynamic stress error and thermal noise error of the phase-locked loop and the frequency-locked loop,so that the frequency-locked loop and the phase-locked loop achieve the best fusion,and finally simulating and analyzing carrier tracking performance.Then,aiming at the contradiction of loop bandwidth selection in the closed loop mode,the carrier tracking algorithm replacing loop filter with Kalman filter is introduced,and its algorithm principle is analyzed.Aiming at the problem that linear Kalman filter algorithm can not adapt to some situations,the principle of extended Kalman filter is introduced.Finally,in view of the defects of carrier tracking in closed-loop mode,a data-assisted carrier tracking algorithm based on least square method is proposed.This method uses the frame structure of the pilot phases and uses the cross-correlation algorithm with the highest accuracy and the lowest computational complexity as the frequency estimation algorithm.Finally,the estimated frequency offset is used as the fitting data of least square method,and the change rate of residual frequency offset and residual frequency offset are estimated by making full use of pilot frequency information.This method gives full play to the advantages of fast estimation speed and high estimation accuracy of time-domain correlation algorithm.In the simulation,the basis for setting the key parameters of the algorithm was summarized.Finally,the correctness of the tracking technology was verified by comparing the compensated QPSK error curve with the theoretical error rate curve.