GNSS Modernisation and Its Effect on Surveying

Lawrence Lau, Gethin Wyn Roberts

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Downloads (Pure)


GPS and GLONASS modernisation is being undertaken. The current GPS modernisation plan is expected to be completed in about 2025. A completely new proposal for GLONASS modernisation has been released on 27th December 2011. In addition to change from FDMA to CDMA, GLONASS may add three more orbital planes to form a constellation of 30 satellites by 2025. Moreover, the new Galileo and Compass are expected to be in full service in about 2020.
This paper describes the latest GNSS modernisation plans in details and how the
modernisation in satellites, signals and constellations affects the positioning accuracy in surveying. Relative positioning technique is usually used in surveying and the baseline length is usually from short to medium (i.e., less than 30 km as defined by the authors). Multipath effect is the main GNSS error source in short to medium baselines. Therefore, impact of GNSS modernisation on multipath mitigation is the focus of this paper.
GNSS modernisation is still on-going, simulation test has to be used to assess the impact of modernised GNSS. Since GLONASS and Compass constellation and signal specifications have not been released officially, impact of the modernised GPS and the new Galileo on multipath mitigation is investigated in this paper. Simulation results show that an about 70% improvement on positioning accuracy in average when compared using combined GPS and Galileo multiple-frequency data with the present GPS reliable single-frequency system (L2C would be available on 24 GPS satellites around 2016). When using three-frequency GPS data, it has shown an about 42% improvement on positioning accuracy in average when compared with the current single-frequency GPS system.
This paper should help surveyors to learn the important aspects of GNSS modernisation in surveying and how GNSS modernisation affects their future surveying practice.
Original languageEnglish
Title of host publicationFIG Working Week 2012
Subtitle of host publicationKnowing to manage the territory, protect the environment, evaluate the cultural heritage. May 6-10 20212. Rome, Italy
Number of pages11
Publication statusPublished - 2012


  • GNSS
  • Modernisation
  • Multipath


Dive into the research topics of 'GNSS Modernisation and Its Effect on Surveying'. Together they form a unique fingerprint.

Cite this