The presentation reports the progress of the CRCSI funded project on "Delivering precise positioning services in regional areas" undertaken by the authors since mid-2007. The project aims to address the technical and business issues that currently constrain GPS-based local area RTK precise positioning services, so as to operate in future larger regional areas, and therefore support services in agriculture, mining, utilities, construction, and others. Selected project findings to be presented will cover the following aspects:
1) An overall technical framework has been proposed to transition the current RTK services to future larger scale coverage in terms of network architecture and operations. The framework enables mixed use of different reference GNSS receiver types, dual- or triple-frequency, single or multiple systems, to provide RTK correction services to users equipped with any type of GNSS receivers.
2) A server-based RTK software platform is being developed to allow for user positioning computations at server nodes instead of on the user's device. This platform can support the implementation of RTK services for various user requirements.
3) Research on data processing algorithms appropriate for triple-frequency GNSS signals has demonstrated some key performance benefits of using triple carrier signals for reliable RTK positioning over long distances. For instance, inter-station distances between triple-frequency receivers can be extended to about 150 km.
4) A software tool has been developed for optimal placement of reference stations in a large scale network, given restrictions such as inter-station distances, candidates of reference locations, and operational modes.