Research On Carrier Tracking Algorithm Of High Dynamic Communication Signal

In the high-speed mobile communication environment,the relative motion between the receiver and the transmitter will cause the Doppler effect,which will shift the carrier frequency of the received signal and affect the reliability of signal reception.The carrier frequency offset of the communication signal will affect the receiver’s tracking performance to the carrier signal.Therefore,it is of practical significance to study the carrier tracking algorithm in high dynamic environment.The main contents of this paper include:1.The paper briefly describe the communication signal modulation methods including amplitude keying modulation,frequency shift keying modulation,phase shift keying modulation and quadrature amplitude modulation.Then it briefly describe the receiver’s components and working principle for the tracking system,then derive the mathematical model of the highly dynamic communication signal,and finally analyze the effect of the high dynamics on the signal.2.It summarize the traditional communication signal carrier tracking algorithm including phase-locked loop and frequency-locked loop,introduce the principle structures of the numerically controlled oscillator and loop filter,and then study and analyse the digital discriminator in the phase-locked loop and frequency-locked loop.After that,it will perform error analysis,which means that the relationship between dynamic stress error and loop bandwidth,as well as thermal noise error and loop bandwidth.In addition,it analyse the working principle of the combined phase-locked loop and frequency-locked loop algorithm for high dynamic communication signal tracking.3.The paper introduce the working principles and filtering steps of Extended Kalman Filter(EKF),Particle Filter(PF),and Extended Particle Filter(EPF).Three types of parameter estimators are used to replace the tracking loop of the loop filter,in which the phase difference between the carrier signal and the received signal generated by the oscillator is used as the state quantity of the tracking loop,the result of the arc tangent discriminator as the Observational measurement.And the parameter estimator will be used to construct a loop filter so as to obtain a carrier tracking loop model.The research results show that:(1)In the carrier tracking loop,if the carrier-to-noise ratio does not reach 27dB-Hz,the phase-locked loop will not track highly dynamic communication signals.If the carrier-to-noise ratio does not reach 29dB-Hz,the frequency-locked loop will not track highly dynamic communication signals.Therefore,when tracking signals with a phase-locked loop or a frequency-locked loop,the unlock looping problem is likely to occur under low carrier-to-noise ratio.(2)The paper will verify effectiveness and reliability of the three algorithms of extended Kalman filter,particle filter,and extended particle filter.Tracking the carrier with the extended particle filter has the highest accuracy.