Research And Implementation On The Reception Processing Of The AltBOC-Based Navigation Signal

The Global Navigation Satellite System(GNSS)has become an important part of social development and affects people's life a lot.As many countries have successively bulit satellite systems,the contradiction of tight spectrum resources has become increasingly prominent.In order to alleviate this problem and improve the performance of satellite navigation services,the researchers proposed a series of new satellite signals,which makes traditional satellite navigation signal quality evaluation techniques no longer applicable.Considering that signal quality evaluation technology is an important guarantee for the normal operation of satellite navigation systems,it is necessary to study quality evaluation techniques for satellite navigation signals of the new system.This dissertation focuses on the reception and quality assessment of alternating binary offset carrier(AltBOC)signals.This project has designed a platform for reception and quality evaluation of new system navigation signals,including radio frequency module,baseband processing module and host computer.The RF module is responsible for amplifying,converting and sampling the received signal,and transfering the sampled digital intermediate frequency signal to the baseband processing module.The baseband processing module is based on a Kintex-7 FPGA(field programmable gate array),mainly responsible for capturing and tracking the signal,and also transmitting the result to the host computer through the Gigabit Ethernet interface.The host computer uses the received data to complete the quality evaluation of the navigation signal.The main work of this thesis lies on the FPGA,including the capturing and tracking of navigation signals,and Gigabit Ethernet communication between FPGA and PC.Specifically,this thesis first analyzes the modulation technology and signal characteristics of AltBOC signals,and studies a series of capture algorithms for AltBOC signals,including single-sideband capture algorithms,double-sideband joint non-coherent capture algorithms,and double-sideband joint coherence capture algorithms.The advantages and disadvantages of these algorithms has been analyzed in this thesis,from the perspective of low hardware costs.Single-sideband capture was selected as the final implementation algorithm.In the tracking algorithm,we use the traditional "carrier tracking loop + code tracking loop" implementation.This thesisvalidates the designed algorithm which can meet the accuracy requirements by using MATLAB.Then,this scheme is implemented on FPGA,including the system's capture module,tracking module and network port communication module.First we introduce the structure of the overall module and the interface design,then give the hardware simulation timing verification results of some important modules.Second we illustrate the correctness of the overall module design.Third the corresponding board-level test results are given in the capture section to verify that the capture process can work correctly on the FPGA.In the tracking module,the network port is utilized to transmit the data to the host computer.And the corresponding signal quality evaluation is also completed on the host computer.This thesis has first completed the capturing and tracking module of the AltBOC signal,then implemented Gigabit Ethernet communication on FPGA.Finally,by using the data which is sent by FPGA to finish the signal quality evaluation,we verify that the work on the FPGA meets the accuracy requirements.