Evaluation of adaptive loop-bandwidth tracking techniques in GNSS receivers

Iñigo Cortés, Johannes Rossouw van der Merwe, Jari Nurmi, Alexander Rügamer, Wolfgang Felber

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
131 Downloads (Pure)


Global navigation satellite system (GNSS) receivers use tracking loops to lock onto GNSS signals. Fixed loop settings limit the tracking performance against noise, receiver dynamics, and the current scenario. Adaptive tracking loops adjust these settings to achieve optimal performance for a given scenario. This paper evaluates the performance and complexity of state-of-the-art adaptive scalar tracking techniques used in modern digital GNSS receivers. Ideally, a tracking channel should be adjusted to both noisy and dynamic environments for optimal performance, defined by tracking precision and loop robustness. The difference between the average tracking jitter of the discriminator’s output and the square-root Cramér-Rao bound (CRB) indicates the loops’ tracking capability. The ability to maintain lock characterizes the robustness in highly dynamic scenarios. From a system perspective, the average lock indicator is chosen as a metric to measure the performance in terms of precision, whereas the average number of visible satellites being tracked indicates the system’s robustness against dynamics. The average of these metrics’ product at different noise levels leads to a reliable system performance metric. Adaptive tracking techniques, such as the fast adaptive bandwidth (FAB), the fuzzy logic (FL), and the loop-bandwidth control algorithm (LBCA), facilitate a trade-off for optimal performance. These adaptive tracking techniques are implemented in an open software interface GNSS hardware receiver. All three methods steer a third-order adaptive phase locked loop (PLL) and are tested in simulated scenarios emulating static and high-dynamic vehicular conditions. The measured tracking performance, system performance, and time complexity of each algorithm present a detailed analysis of the adaptive techniques. The results show that the LBCA with a piece-wise linear approximation is above the other adaptive loop-bandwidth tracking techniques while preserving the best performance and lowest time complexity. This technique achieves superior static and dynamic system performance being 1.5 times more complex than the traditional tracking loop.

Original languageEnglish
Article number502
Number of pages40
JournalSensors (Switzerland)
Issue number2
Publication statusPublished - 2 Jan 2021
Publication typeA1 Journal article-refereed


  • Adaptive scalar tracking loop (A-STL)
  • Fast adaptive bandwidth (FAB)
  • Fuzzy logic (FL)
  • Global navigation satellite system (GNSS)
  • Loop-bandwidth control algorithm (LBCA)
  • Piece-wise linear approximation of non-linearities (PLAN)

Publication forum classification

  • Publication forum level 1

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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