Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments

Liqiang Zhu, Ying-Cheng Lai, Mayur Shah, Sultan Mahmood

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Precise GPS positioning relies on tracking the carrier-phase. The fractional part of carrier-phase can be measured directly using a standard phase-locked loop, but the integer part is ambiguous and the ambiguity must be resolved based on sequential carrier-phase measurements to ensure the required positioning precision. In the presence of large phase-measurement noise, as can be expected in a jamming environment for example, the amount of data required to resolve the integer ambiguity can be large, which requires a long time for any generic integer parameter estimation algorithm to converge. A key question of interest in significant applications of GPS where fast and accurate positioning is desired is then how the convergence time depends on the noise amplitude. Here we address this question by investigating integer least-sqaures estimation algorithms. Our theoretical derivation and numerical experiments indicate that the convergence time increases linearly with the noise variance, suggesting a less stringent requirement for the convergence time than intuitively expected, even in a jamming environment where the phase noise amplitude is large. This finding can be useful for practical design of GPS-based systems in a jamming environment, for which the ambiguity resolution time for precise positioning may be critical.

Original languageEnglish
Pages (from-to)149-156
Number of pages8
JournalJournal of geodesy
Volume81
Issue number2
Early online date24 Oct 2006
DOIs
Publication statusPublished - Feb 2007

Keywords

  • integer ambiguity resolution
  • integer least squares
  • precise GPS positioning
  • noise
  • jamming
  • linear-models
  • decorrelation

Cite this