Research And Implementation Of GPS RTK Wireless Data Link

With the development of GNSS,GPS RTK has been widely used in various control measurement,terrain mapping,project layout and real-time navigation and positioning.It has changed the traditional measurement mode,brought revolutionary changes to engineering measurement and greatly improved the efficiency of engineering measurement.The GPS RTK reference station transmits the observed carrier phase observations and station coordinates to the mobile station through operator wireless network or a radio in real time.The mobile station obtains centimeter-level positioning results after real-time differential processing.Because of low operating cost and easy maintenance,and in areas where the mobile network are not covered or have poor network,radio is used to make up for communication blind spots,assist netwok communication.GPS RTK is equipped with internal radio and external radio.The internal radio can replace the external radio for sending and receiving data within short distance.The internal radio in the original GPS RTK wireless data link has a short communication distance(2Km).The high power consumption(over 10W)and large volume of the external radio requires additional battery and cable,which is extremely inconvenient to use.Aiming at the defects of the radio mentioned above,design and implement a low bit error rate,high integration and low power consumption of transceiver digital radio that can be used as an alternative to external radio in 8 Km.The shackle of heavy batteries and cables is got rid of,making the operation more flexible and convenient.This article describes the composition of the GPS RTK system,measurement principle and error analysis firstly;secondly,describes and simulates several common digital radio programs,important parameters and key technologies;then considering the requirements of low power consumption and miniaturization of this subject,design a micro-power digital radio according to the actual requirements of the system,design the system block diagram and system implementation,analyze each module detailedly;finally,test and analyze the system.The GPS RTK micro-power digital radio designed uses LoRa spread spectrum technology to increase the sensitivity and transmission distance,uses RS encoding and decoding technology to reduce the bit error rate of digital radio.Based on the LoRa spread spectrum data transmission chip and the micro controller STM32 as the core,a long-distance,micro-power digital radio is designed By testing,all indicators meet the requirement and achieve a better result.It achieves a transmission distance of 8Km in 1W with bit error rate less than 10-7.