Development Of Special Receiver For Multi-mode Multi-frequency CORS Base Station

The Continuous Operational Reference System(CORS)is an infrastructure for achieving high-precision navigation and positioning from centimeter to millimeter.It is widely used in the fields of land resources,surveying and mapping,transportation and meteorology.The base station provides the GNSS original observation data for the CORS system.The functional performance of the base station receiver and the quality of the observed data are one of the key factors in determining the service level of the system.This paper designs and realizes the CORS base station receiver which is compatible with the three-system eight-frequency point,realizes the quality of the base station receiver data and develops the embedded remote control and service software.The main research work is as follows:Developed a multi-mode multi-frequency CORS base station dedicated receiver hardware platform.Based on ARM9 processor,integrated UB380 board,built the base station receiver hardware platform including power module,Ethernet module,serial module,satellite positioning module,display module and storage module.On the hardware platform transplant Linux operating system,and based on the PC and ARM9 core board to build embedded development platform for the follow-up embedded software development to provide hardware and software conditions.Quality analysis and evaluation of real-time observation data of multi-GNSS base station receivers.The algorithm of PDOP value,multipath effect,data integrity and satellite signal-to-noise ratio is studied,and the quality of the observation data of the base station receiver is analyzed and evaluated by the measured data.The experimental results show that the PDOP of GPS/GLONASS/BDS system is less than 2,the MP1 value is less than 0.05m,the MP2 value is less than 0.17m,and the data integrity is more than 95%.SNRI and SNR2 average are greater than 40dB-Hz,base station receiver observation data quality is better to meet the requirements.Developed the base station receiver embedded remote control and service software(GoAhead WebServer).Using GoAhead provided GoForms process and ASP process to achieve the software function modules.To realize the authentication and registration function to ensure the security of the base station receiver information;to realize the display and setting function of the network information,to support the remote modification of the base station receiver network information;to realize the coordinate setting function,to support the remote setting of the base station receiver precision coordinates;Transmission mode setting function,to support the remote setting of data format and transmission mode;to achieve the sky map and data quality information display,real-time monitoring of data quality;to achieve data download function,support remote download GNSS raw data.CORS base station receiver stability,data quality and remote control functions such as testing and verification.The test results show that the base station receiver voltage is stable with the standard voltage deviation within 0.1 V;the network communication capability is good,the data integrity rate is greater than 99.99%;can cycle store the GNSS raw data for two months;the base station receiver full day multipath value In the 0.04m below the signal to noise ratio greater than 45dB-Hz,data integrity of more than 95%,week jump detection ratio of more than 80,000,the base station receiver data quality is better to meet the needs of CORS system construction;base station receiver remote control capability,support remote set coordinates,data format and transmission,real-time display GNSS sky map And data quality information,download GNSS raw data and other functions,operable.