A Fast Ambiguity Resolution Technique for RTK Embedded Within a GPS Receiver

Yunchun Yang, Richard T. Sharpe and Ronald R. Hatch

Abstract:	GPS carrier phase integer ambiguity resolution is still the key issue and challenge for high accuracy RTK survey and navigation. Due to speed and memory limitations of O EM G PS receiver boards, the calculation efficiency is of prime importance since it affects the elapsed time before ambiguities can be resolved. Of course, the reliability of the ambiguity resolution process is also a significant concern. A new technique is presented based upon the Residual Sensitivity Matrix [8], which relates the search integer ambiguity set to each carrier phase residual directly. The technique uses the Singular Value Decomposition of the Residual Sensitivity Matrix to find the minimum search space. The technique not only improves the calculation efficiency and ambiguity resolution time, but also improves the reliability. The search space is minimized by selecting only those combinations of possible ambiguity values which are consistent with the satellite geometry and the measurement residuals. The technique has been implemented within NavCom Technology's NCT 2000D GPS OEM engine. The RTK function embedded within the engine is a background process, which takes about two seconds elapsed time to search a single epoch of data using a 20MHz CPU. Ex- tensive experimental data shows that 85% of the searches yield the correct integer ambiguity resolution using a sin- gle epoch of data within a 9 km baseline. Test results in different scenarios are shown in the article. KEY WORDS: Global Positioning System (GPS), Ambiguity Resolution, Real Time Kinematic (RTK), Residual Sensitivity Matrix, and Singular Value Decomposition.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	945 - 952
Cite this article:	Yang, Yunchun, Sharpe, Richard T., Hatch, Ronald R., "A Fast Ambiguity Resolution Technique for RTK Embedded Within a GPS Receiver," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 945-952.
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