Development Of A Convenient RTK Differential Positioning System Based On Micro-reference Station

Carrier phase differential positioning technology is becoming more and more mature,static positioning accuracy can reach millimeter level,and its related products have been used in deformation monitoring,marine surveying and mapping,precision agriculture and other fields.Aiming at the problems that the differential equipment has too high cost,the initial base station coordinate positioning time is too long,the working efficiency is low,and it is difficult to disassemble and maintain,this paper develops a convenient real-time dynamic carrier phase differential positioning based on micro reference station Real-time Kinematic(RTK)system,the specific research is as follows:First,it briefly describes the development and composition of the Global Navigation Satellite System(GNSS),introduces the basic positioning principles of satellites,which mainly include pseudorange observation positioning and carrier phase observation positioning,and analyzes the various types of positioning Positioning error,explained the principle of using differential positioning technology to eliminate part of the error and improve accuracy,and then researched RTK technology.Then on the system hardware,a reference station structure with micro industrial control computer as the core is designed,which has the characteristics of high performance,high stability and convenient operation.Self-designed Beidou / GNSS low-cost receiver based on ARM Cortex-M7 architecture STM32F767 processing chip and UBLOX-M8 T satellite signal receiving chip development,including core processor circuit,power management circuit,SDRAM memory expansion circuit and satellite signal receiving Circuit etc.A variety of communication links such as CD-Radio broadcast and wireless bridge are designed,and the appropriate communication link is selected according to the communication needs of different scenarios to reduce the system cost.Then,based on the hardware design,the software design of the system is implemented,including the software design of the base station,the software design of the Beidou / GNSS low-cost receiver,and the design of the mobile phone differential resolution.The micro base station software design adds Chihiro service to assist the initial base station coordinate positioning,and obtain millimeter-level base station coordinates in a short time;develop the upper computer under QT environment to complete the positioning data visualization and related satellite parameter configuration and other functions.Beidou / GNSS receiver software design circular queue algorithm for serial communication,improve the success rate of data communication;realize RTCM3.2 encoding,reduce data volume and reduce transmission pressure.The mobile phone differential resolution design can search the surrounding Bluetooth devices and complete pairing connection and data transfer.Receive the mobile station observation data,micro base station observation data and base station coordinates through the mobile phone Bluetooth to complete the differential resolution calculation to achieve high-precision positioning.Finally,when the coordinates of the micro-reference station are known and the observation environment is good,the static positioning error in the E direction is 5.9mm,the N direction error is 7.2 mm,and the U error direction is 18 mm.The horizontal error is better than 1cm,the vertical error is better than 2cm,and the fixed rate reaches96.5%.The system is specifically designed to achieve overall low cost,high efficiency and convenience design while positioning with high precision.