| Mobile Internet,big data,cloud computing,Internet of things and other technologies,through mobile terminals to provide all kinds of intelligent application services,is profoundly changing the concept and way of public life.With the large-scale popularization of intelligent terminals,the potential of intelligent terminal positioning applications has been further explored,and a large number of terminal application services such as intelligent travel,intelligent transportation,intelligent fitness,intelligent environmental protection and so on have emerged.At present,the Android user share of domestic intelligent mobile terminal is as high as 86%.But the real-time positioning accuracy of ordinary Android terminal is only 10 m.How to improve the real-time positioning accuracy of Android terminals and meet the requirements of high precision location service for mainstream mobile terminals has become an urgent frontier technical problem and urgent application needs.Combined with the open source architecture of Android system and the high precision advantage of wide area precision positioning technology,this paper launchs the single-frequency wide area precision positioning algorithm of Android mobile terminal and the development of application program.Taking the Android mobile terminal as the application carrier and using the real-time wide area precision positioning technology,the correction information such as precision orbit,clock and ionospheric delay are obtained online.The positioning accuracy of global real-time single-frequency positioning is better than lm.The theoretical research,scheme design,experimental analysis and Android terminal application development of real-time single-frequency wide area precision positioning have been completed,and the positioning accuracy of Android mobile terminal has been greatly improved.(1)The principle,model,algorithm and flow of single-frequency GNSS real-time precise positioning are studied and realized from the requirements of popularization?low cost and single-frequency GNSS module integrated into smart phone.This paper describes the production and acquisition method of GNSS real-time precision orbit and clock correction information,analyzes the correction information of real-time precision orbit and clock of four systems in detail,and realizes the correction model of real-time correction number..(2)A m-level convenient single-frequency real-time and high-precision positioning scheme is provided.This scheme uses only real-time precise orbit,clock correction information and broadcast ionospheric model through online network.The accuracy of single-frequency real-time positioning is less than 2m,and the positioning result is stable.Compared with the common single-frequency real-time positioning,the positioning accuracy has been improved 45.5%.This scheme does not need to download the forecast product in advance and is convenient to use.It can satisfy the single-frequency and high precision position service of about 2 meters.(3)A sub-meter single-frequency real-time precision positioning scheme is provided.Through online network,using real-time precise orbit,clock correction information and grid ionospheric prediction products,the static single-frequency real-time positioning accuracy is 0.5 m,and the dynamic single-frequency real-time positioning accuracy is 1 m.Compared with ordinary single frequency real-time positioning,the accuracy of dynamic positioning mode has been improved by 72%.This scheme only needs to download the ionospheric grid forecast product in advance,and it can satisfy the precision position service of single frequency in sub-meter level.(4)In view of the low cost of Android terminal,high user share but lack of precision positioning service and application program,a set of single-frequency GNSS real-time precise positioning software for Android user terminal is developed.The Android frame structure is used to realize the meter level convenient and sub-meter precision single frequency positioning service.Development of terminal serial driver,read mobile terminal RTCM MSM4 BDS satellite original observation data.Access network layer differential information,obtain and analyze real-time orbit,clock correction.The single frequency phase and pseudo-range original observations are used to broadcast the ionospheric model and Grid ionosphere model to achieve high precision of decimeter level. |
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