| In recent years,the global navigation satellite system(GNSS)plays an increasingly important role in the field of military and civilian,and the application scopes of GNSS have been more and more widespread.As the application environment is becoming more and more complex,the performance requirements for GNSS software receivers continue to increase,while the traditional software receivers have been difficult to meet the actual needs.Therefore,Based on the scalar tracking of traditional software receivers,this paper deeply studies the vector tracking technology.Vector tracking technology is an advanced navigation technology in GNSS research,which is a research hotspot in recent years.Unlike scalar tracking,the vector tracking technique integrates the tracking part and the positioning solution of the traditional software receiver,and amplifies the tracking loop.The measured values of the combined channels are made to estimate the position speed and so on by the navigation filter to feedback to adjust the loop operation.Vector tracking technology makes full use of channel’s correlation to improve tracking performance and positioning accuracy.In this paper,the main contents are as follows:Firstly,the composition and characteristics of GNSS signal are analyzed and introduced,which lays the foundation for the realization of tracking technology.At the same time,the principle of navigation and positioning is expounded,in which the positioning information needs to obtain the demodulated navigation data from the tracking part to calculate the satellite position,and the pseudo-code phase measurement value is needed to calculate the pseudo-range,so the purpose of tracking is clear.Then the scalar tracking technology in traditional software receiver is studied.The principle of phase-lock loop,the establishment of carrier loop and the establishment of code loop are analyzed,and the error output of frequency – lock loop and phase – lock loop are studied.Simulation of scalar tracking technology coupled by carrier loop and code loop shows that scalar tracking can meet the requirement of GNSS signal tracking under normal conditions.Then,based on the scalar tracking,the vector tracking model is established by using the delay lock loop and the frequency-lock loop.The navigation filter of extended Kalman filter is analyzed on the vector tracking,The state equation of the vector tracking and the establishment of the measurement equation are studied emphatically,and the vector tracking process is described.Finally,the performance of vector tracking is analyzed.It is concluded that the variance of the pseudo-range error in the vector tracking is less than the scalar tracking when the number of satellites is greater than 4.Through the experimental simulation,compared with scalar tracking,the vector tracking has higher positioning accuracy and more suitable use for high dynamic,fast reacquisition,and certain inhibitory effect on interference. |
