Critical issues on GPS RTK operation using Hong Kong GPS active network

Wu Chen, C. Hu, Xiaoli Ding, Y. Chen, S. Kwok

Research output: Journal article publicationJournal articleAcademic researchpeer-review


The Lands Department of Hong Kong is establishing a permanent GPS array of reference stations for various applications. It collects GPS data continuously from multiple reference stations and delivers quality-checked data to users. This well-positioned and dense array of reference stations is designed to allow users to achieve cm-level accuracy within a short period of time, even using one low-cost single frequency GPS receiver. It will also support meter-level navigation and transportation management applications using DGPS correction. The array of permanent GPS stations can also be used for scientific research, such as deformation monitoring and weather forecasting. The station spacing for the active network is about 10 to 15 km, and there will be 13 to 14 stations covering the whole territory. The main challenge today is how to implement the network solution using carrier phase measurement in real-time operation. In order to achieve this, there are still some problems to be overcome. For example, the ionosphere in Hong Kong is highly active during the daytime. This causes a serious problem for carrier phase ambiguity resolution. This paper investigates a number of important issues associated with the real-time operation of the network, including atmospheric corrections and system integrity. Possible solutions to these problems will also be proposed in this paper.
Original languageEnglish
Pages (from-to)31-40
Number of pages10
JournalJournal of geospatial engineering
Issue number1
Publication statusPublished - 2002


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