Research Of The Phase-Locked Loop Acquisition And Tracking Technology Under Doppler Shift Condition

With development of communication technology, information exchanging is gradually becoming a more important problem of the research in information industry. Especially made a higher demand of the satellite communication and the accuracy of information senting or successful receiving is the protection of the satellite normal operation. Because of long-distance transmission process the information will be impacted of the serious noise, and then a Phase-Locked Loop signal processing unit should be added in, as for signal fast acquisition and fast error-free tracking. In this paper, we analysis and compares the internal and external present researches of the Phase-Locked Loop on the acquisition and tracking performance , from another angle to research this problem.Firstly, this paper analyzes the mathematical model based on the basic components of the Phase-Locked Loop, form the angle of function relationship, we analysis the stability properties of the Phase-Locked Loop. And then through the research of acquisition and tracking algorithm in Phase-Locked Loop, we master more of the tracking characteristics, and understand their own deficiencies of the acquisition.Secondly, for the choice of the loop bandwidth have conflicts with the suppression of input noise and frequency traction, in this article we analyzing the basic theory and components of the traditional Phase-Locked Loop, established a mathematical model of the aid acquisition Phase-Locked Loop. By simulation, draw the phase trajectory diagram and time response plans under different conditions, found out the acquisition belt relate to any initial phase error. Experiments show that this method is effective to resolve the conflicts between the choice of loop bandwidth and noise filtering or frequency traction, all of these will have certain guiding significance in engineering applications.Finally, according to second-order phase-locked loop can not meet the precision velocity under the condition of Doppler, this paper established a mathematical model of fourth-order Phase-Locked Loop, analysis of the fourth-order loop filter parameter design principles and methods, gives digital diagram of the loop filter and the simulation results of track the satellite Doppler shift capacity. Experimental results show that this method has advantages in achieving the Doppler shift of the satellite tracking.