Research On The Application Of CORS-based Differential Positioning Module In Construction Land Site Surveillance

Because of the large population and the relative deficient available land resource, the land per capita problem in our country is obvious. By the transformation of three-old(old towns, old factories and old villages), situation of short supply and bottlenecks of land utilization can be remitted efficiently. With the development and application of computer, video monitor, wireless network transmission, GPS and GIS, three-old transformation is not a single site transforming project. By installing surveillance cameras in three-old transformation site then transmitting surveillance video to three-old transformation management platform, which allows it to call the video on the electronic map at any time, three-old transformation can be unmanned, intelligent and real-time. During the process, the camera used in three-old transformation site needs high precision positioning then it can connect with electronic map on the backstage. In traditional positioning technology, the low precision of single-machine position can not meet the demand of high precision positioning so that people often improve the positioning precision by differential positioning method but the establishment of differential positioning base station is complex.Meanwhile, as the distance between client and base station increases, the positioning precision decreases. However, the appearance and development of CORS(Continuously Operating Reference Stations) make it impossible to solve these problems. Therefore, it is necessary to research and to develop high precision differential positioning technology.In this project, three-old transformation construction land site surveillance is regarded as researching background, by analyzing and studying current GPS positioning technology, differential positioning technology and the application status of CORS technology, a differential positioning module based on CORS is designed, which can be used in the fixed point monitoring and high precision positioning of moving point surveillance camera during the three-old transformation. The positioning module uses STM32F407VGT6 as main control chip, P307 of Hemisphere as GPS positioning board card and 4G(U8300W) network module and its peripheral circuit of Longsung as differential data transporting module, including the hardware such as power supply module, SD card, USB interface circuit and debugging circuit. Based on the hardware condition, software focuses on researching the programs such as dialing up internet accessing of 4G wireless network module, positioning data reading of GPS board card, client accessing of Ntrip and file storage of SD card. Finally the main performance of high-precision differential positioning module including the position precision in different situations such as static or dynamic, clear or overcast is analyzed and tested.Using the high precision differential positioning module in three-old transformation construction site can remit the inconvenience of establishing base station, meet the positioning demand of construction site surveillance cameras, ensure the real-time of transporting positioning data and benefit the docking between the site surveillance and backstage management.