Design And Implementation Of Low-cost,Real-time Differential Positioning System

One of the most common ways to position in the world is satellite navigation system.So far,the satellite navigation system is widely applied in various fields,such as trace of oceangoing ships,quickly locating and rescuing if the ship fails.Meanwhile satellite navigation system is used to plan the travel route of city vehicles to avoid the traffic jam.It also can be applied in various grades of geodesy,unmanned aerial vehicle(UAV)remote sensing,mountain deformation monitoring,etc.Satellite navigation systems,represented by the GPS,have occupy an extremely important place in our national life.When sending the signal to the ground,GPS system will exist satellite clock error,ephemeris errors and be affected by earth's outer atmosphere signal transmission.Meanwhile There are GPS user receiver clock offset and error of measurement noise interference.All these shortcomings will reduce receiver positioning accuracy.With the rise of the Internet of things,new Internet equipment has a surge in demand for the satellite navigation and positioning device module.Due to various restrictions,low-cost GPS equipment level positioning accuracy in 4 to 5 meters,it usually can't satisfy the demand of Internet of things device application.Hence although the traditional differential GPS devices while positioning accuracy is high,the quality of its bigger size and could not be loaded into some embedded devices,meanwhile high prices for ordinary users are also unbearable.According to the above problems,considering the hardware price,volume,power consumption,versatility and degree of system upgrade,this article designs and implements a low-cost real-time differential positioning system.The main work is as follows:1)Firstly,this article analyses the current development of DGPS equipments at home and abroad.Secondly,it expounds the pseudo-range difference and RTK.Moreover,doppler method is applied to solve carrier cycle slip and LAMBDA method is used to work out integer ambiguity and give the detailed steps.2)Firstly,this designed system decodes UBX data,gets the raw data and calculates satellite coordinates.Secondly,RTCM data is decoded to get differential correction data.And then,two types of differential positioning are run on the embedded devices.The analysis of positioning accuracy is provided in this paper.3)Firstly,the solution is proposed to deal with the differential delay during the DGPS process.Meanwhile,some related design work are carried on for communication interruption.This designed system can run single point positioning automatically when the differential signal interrupts.