Design Of CORS Reference Station Receiver

With the continuous development of navigation and positioning technology and the further improvement of CORS system,the level and capability of satellite navigation in China has entered a new era.Multi-mode and multi frequency observation information can provide more accurate and reliable location results.In particular,the coexistence of multi system technology conditions is the basis and prerequisite for the realization of high quality observation data.Satellite reception,as an important part of the reference station system,is responsible for the functions of satellite signal receiving,data analysis and distribution and location calculation.Because the quality of the performance of the receiver and the original observation data are closely related,directly affect the further analysis of the data quality of the navigation client and subsequent processing,so as to improve the performance of the receiver and increase the data capacity and server performance processing receiver,for the whole CORS system reference station data distribution and parsing efficiency and data transmission rate it is of great significance.This paper is based on the CORS reference station satellite navigation and positioning system,the research and development of the reference station receiver software system,the main research contents are as follows:(1)The hardware structure of the receiver,analyzes the OEM board positioning module and Application module,application module using the Linux embedded system,the 32 bit ARM processor,by controlling the external communication interface circuit,WIFI and Bluetooth module,a central processor unit,a network interface between each module,through the UART interface to achieve data exchange,a hardware circuit design stable and reliable.(2)The receiver the original data analysis,RINEX data format conversion,GNSS receiver the original data stream on the message format and content and application,analyzes the organization structure and the message receiver the original binary message,the analytical method of the message,and the design flow chart of the specific message analysis,according to the analysis principle of message.In the field of information extraction of message integrity,correctness and obtain information through the final conversion by RINEX file verification.The paper also analyzes the file format,composition and basic information of the RINEX3.02 version.(3)Research on the framework of the multi process additional threads under the Linux platform software,to optimize the design of the software receiver,emphatically analyzes the design framework of EPOLL server mechanism and thread pool and memory semaphore set and mutex method used by using the shared,effective implementation of the communication between processes and threads the function of data sharing and data sharing,efficient access coordination between multiple threads,which effectively improves the performance of the server software receiver,and improves the processing ability of the data receiver.At the same time,in order to improve the utilization rate of the receiver memory space of dynamic storage management algorithm,according to the requirements of space allocation of memory tasks,and timely recovery of the free space,greatly optimizing the receiver memory use,reducing waste of memory fragment.And this paper designs the client software of the receiver,and pushes up the upgrade file through FTP to realize the batch upgrade of multiple receivers.(4)At the end of the various indicators of quality error source of GNSS data,the receiver data processing to judge the reliability and accuracy of the original data of the receiver quality analysis,further fully showed that the receiver is stable,data analysis and distribution,and the realization of the right,from the reference station receiver of high quality,is of great significance for the CORS system the construction of high precision and high efficiency.