GPS Solutions

, Volume 11, Issue 4, pp 259–268 | Cite as

Single epoch ambiguity resolution for Galileo with the CAR and LAMBDA methods

  • Shengyue Ji
  • Wu Chen
  • Chunmei Zhao
  • Xiaoli Ding
  • Yongqi Chen
Original Article


This paper investigates single epoch ambiguity resolution performance using Galileo four frequency data. Two commonly used ambiguity resolution methods are used in the tests, including the Cascade Ambiguity Resolution (CAR) and the Least-Squares Ambiguity Decorrelation Adjustment (LAMBDA) methods. For CAR method, four optimal combinations are carefully selected according to their wavelength to noise ratios and success rate for ambiguity fixing. The test results show, in general, the LAMBDA method performs better than the CAR method. The speed of ambiguity resolution is closely related to the carrier phase measurement precision. With carrier phase measurement precision of 3 mm, single epoch ambiguity resolution can be achieved at every epoch with simulated 1-s interval 24-h Galileo data (total epochs 86,400). With the increase of carrier phase noise, ambiguity resolution performances become worse. When the noise level is increased to 12 mm, single epoch ambiguity resolution can only be achieved about 50% of epochs.


Ambiguity resolution Galileo CAR method LAMBDA method Success rate 


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Shengyue Ji
    • 1
  • Wu Chen
    • 1
  • Chunmei Zhao
    • 2
  • Xiaoli Ding
    • 1
  • Yongqi Chen
    • 1
  1. 1.Department of Land Surveying and Geo-InformaticsThe Hong Kong Polytechnic UniversityHong KongChina
  2. 2.Chinese Academy of Surveying and MappingBeijingChina

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