Design And Realization Of High-Dynamic GNSS Dual-Mode Receivers

At present,the navigation receivers which China and other countries all over the world mainly use mostly rely on the GPS satellite navigation system of US.At the meantime,China has been devoting itself to the manufacturing and developing of the Bei Dou Navigation Satellite System.The development of the Bei Dou Navigation Satellite System makes it a strong backup and support in the fields of rescuing,navigation and military affairs in China,and corresponding military models demand that the Bei Dou Navigation Satellite System should be used in navigation and positioning.In view of the fact that GPS and the Bei Dou Navigation Satellite System 2 are the typical systems of GNSS,and the developing goals of GLONASS and Galileo are both compatible with GPS system,this project selects the GNSS receiver who is the most typical and the two mode combination of GPS and the Bei Dou Navigation Satellite System.With the Bei Dou Navigation Satellite System as the main part and GPS the supplementing part,this project researches on the two mode receiver which can provide accurate positioning continuously and effectively under high dynamic conditions.Meanwhile,the flexibility of the system is also considered so as to adapt to all kinds of GNSS systems.This thesis mainly includes three parts,namely the processing of RF,the processing of digital IF signal and software PVT solution.The part of radio-frequency circuit have accomplished wave filtering,amplifying and down conversion as well as AD conversion towards received satellite signals.As for the two mode receiver,the front design of radio-frequency circuit is the same-receive the satellite signals via antenna wire,and amplify the signals by low noise amplifier and filter the waves by surface acoustic wave filter,after which the noise in the received satellite signals will be greatly lowered.Then the power divider is used to divide the received satellite signals into two parts,namely GPS and the Bei Dou Navigation Satellite System,which will be independently processed.The processing of digital IF signal is accomplished by FPGA and DSP,consisting of the seizing,tracking and data demodulating of GPS signals.It aims to get the navigation message data and C/A mode phase and Doppler frequency etc.and gain the location,velocity and time of receiver from the navigation data structure.In order to track and demodulate GPS signals,visible GPS signals should be seized firstly and the necessary parameters of the seized GPS signals should be transmitted to the tracking circuit through which the navigation messages of satellite are demodulated.Seizing is directing against a certain satellite signal and searching within possible Doppler frequency area and C/A code phase area so as to get the starting point and wave carrier frequency of C/A mode which inputs the signal,so that the tracking can be conducted within a relatively small area towards the input signal and more accurate wave carrier frequency and C/A mode phase can be gained and navigation messages can be demodulated continuously.Seizing provides tracking with wave carrier frequency,C/A code and its phase.Navigation demodulating mainly includes calculating and correcting the possible deviations of receiver according to the ephemeris parameters in navigation data and conducting PVT(Position,velocity and time)demodulation to receiver according to the results,and conducting real-time calculation and monitoring towards each precision factor so as to make sure whether the accuracy of position solution meets demand.On the basis of these steps,this thesis optimizes the software algorithm and designs a GNSS observation software which can not only check the navigation data,tracking satellites and positioning used satellites,satellite carrier to noise ratio and historical tracks,but also record and playback recorded data to observe and analyze the results.After the research and development of high dynamic receiver,low power consumption,small volume,high reliability,high performance and other features are optimized further.We learn from application and verify application in learning and will be committed to the research on miniaturization and higher dynamics.