Research And Implementation On Real Time Single Point Positioning Of Android Smartphones

The developement of GNSS(Global Navigation Satellite System)is growing rapidly,and providing people with all-weather navigation and positioning services.Android phones have a large number of users.After Google opened the original measurement information of GNSS,researchers and users have put forward higher requirements for GNSS positioning of android phones.At present,most researches focus on improving the positioning accuracy of android phones,and there are few researches on real-time dynamic positioning of android phones in different dynamic scenarios.Therefore,based on four common android phones in the market,MI8,Huawei P40,Huawei mate20 pro and Huawei P30,this thesis gives full play to android phones advantages of portability,and develops a real-time single point positioning software that takes into account GNSS data quality control.This thesis designs dynamic experiments to explore the potential of android phone dynamic real-time positioning,and analyze the android phone dynamic single point positioning capability in different scenarios.The main contents and achievements of this thesis are as follows:(1)This thesis obtains GNSS measurement data by android phones through Android API,and analyzes the quality of GNSS measurement data from MI8,Huawei P40 and Huawei mate20 pro phones by many indicators.This thesis uses real-time data inspection,outlier detection and elimination,gross error detection,pseudo-distance smoothing to control data quality.The experiment was designed to verify the effectiveness of the quality control method.And the result shows that positioning accuracy of android phones is improved after gross error detection and pseudorange smoothing.The SPP positioning accuracy of MI8 is improved by 43.07% in the E direction,26.34% in the N direction,and 59.07% in the U direction.The SPP positioning accuracy of HUAWEI P40 is improved by 47.34% in the E direction,50.02%in the N direction,and 61.73% in the U direction.(2)From the perspective of Android system architecture and location service architecture,this thesis realizes mixed programming of C language and Java language by JNI,and develops a real-time single point positioning software based on android phones.This thesis designs experiments to analyze the positioning effect of the software.In the experiment of real-time pseudorange single point positioning,real-time SPP positioning accuracy of MI8 and Huawei mate20 pro is about 2 m-4 m in static experiment.The dynamic positioning trajectory of MI8 mostly fluctuates in real-time SPP experiment.But the trajectory of Huawei mate20 pro and Huawei P40 basically coincide with the receiver trajectory,and only a few minor motion trajectory deviations occur when pedestrians turn and in the irregular traveling route.In static PPP experiment,the plane positioning accuracy of android phone is sub-meter level.But due to the limitation of android phones’ dual-frequency GNSS data integrity rate,compared with single-frequency PPP positioning,android phones’ positioning accuracy of dual-frequency PPP is not significantly improved.(3)Based on the positioning software developed in this thesis,designing pedestrian dynamic experiments in common scenes and vehicle-mounted experiments in urban scenes.The results show that the positioning accuracy of android phones in pedestrian dynamic PPP is mostly in the meter level.This thesis selects the open section,the section covered by unilateral trees and the section covered by tall buildings for precise single point positioning.In open road sections,the plane positioning accuracy of android phones was best,up to 1.5m to 2.5m.In single-side tree-shaded road sections,the plane positioning accuracy of android phones can up to 3m to 5m.But when android phones in the car under the block of tall buildings,the plane positioning accuracy of android phone is the worst,and the positioning error can be up to more than ten meters.