The Design And Implementation Of B1/B2 Double-frequency BDS Software Receiver

In recent years,China's independent research and development of beidou satellite navigation system(BDS)is developing rapidly.Its open multi-frequency signal provides a convenient condition to study the BD double-frequency software receiver.The main task of the GNSS satellites receiver is to track visible satellite signal,by digital signal processing,obtaining the observations and the navigation message,finally completing the user receiver positioning,navigation,and timing.The software receiver is convenient for the development of the new algorithm,and can be flexibly used for the verification of a variety of baseband signal processing algorithms,and can process the intermediate frequency data of different formats and the signals of different sampling frequencies.In order to explore the BD double-frequency signal characteristics and research the double-frequency joint baseband signal processing algorithms,improving the satellite signal acquisition,tracking performance.this paper implements a complete set of BD dual-frequency receiver software,and proves the feasibility and stability of the software receiver.In this paper,main contents and achievements include:Firstly,this paper introduces the background of the selected topic significance,the domestic and foreign performance status about the BD receiver software research,and systematically introduces the principle of BD baseband signal processing technology,respectively from the BD satellite navigation system,the structure of the BD satellite signal,and the satellite navigation and positioning technology.Secondly,this paper introduces the BD double-frequency signal capture and characteristic of the algorithm.In which,according to the characteristic of BD signals NH code,local signal zero padding acquisition algorithm is proposed,the analysis and experiment results show that the algorithm can improve the signal capture performance compared with traditional capture algorithm.In this paper,a dual frequency signal aided tracking model is proposed,which uses the Doppler frequency between the dual frequency signals to assist each other.The experimental results show that the tracking performance can be improved by using the aided tracking algorithm,and the tracking signal can still be stabilized at lower carrier to noise ratio,and the tracking performance is better than the traditional tracking algorithmThirdly,based on the BD double-frequency software receiver system,an experiment test is conducted.A complete set of code includes the BD satellite double-frequency signal acquisition,tracking,signal demodulation and single point positioning.According to collecting BD intermediate frequency digital signal and compiling on the VS2010 platform,we can successfully tracking BD satellite double-frequency signal,demodulating the navigation message,the single and double frequency PVT calculation is also carried out.As a result,we confirm the feasibility of the code.This paper proposes the observation combination model to positioning,and analyses the positioning results of single and double frequency.A complete set of BD software receiver implementation has important significance for the future study on BD double-frequency baseband algorithm.In summary,this paper analyses the characteristics of BD double-frequency baseband signal,and studies the BD double-frequency signal acquisition and tracking algorithm.The effectiveness of the proposed method is verified by the verification of the dual frequency joint algorithm,and the acquisition performance and tracking performance of the algorithm are tested,then adopting the model of double-frequency combination pseudorange observation to make single point positioning.The paper gives the software receiver design process and the function of each module,and we test the function of software and analysis accuracy.