An Evaluation of Various Space Clocks for GPS IIF

Abstract

This study projects the accuracy of GPS in the Accuracy Improvement Initiative (AII) environment given current satellite clocks and the future Block IIF cesium and rubidium clocks. AII is an upgrade to the GPS control segment that incorporates additional tracking stations and replaces the current partitioned filter with a fully correlated one. Real data, obtained during two weeks of October 1998, were modified when appropriate for simulated clocks. A simulation of the AII estimator is exercised on these data and its states used to predict user navigation messages, which are then compared to a truth reference. It is concluded that the IIF satellites, using either their cesium or rubidium clocks, would meet the AII accuracy specification assuming one upload per satellite per 6 hours, but that the Block IIA satellites with their cesium clocks would not. An upload rate of once per day is possible only with the IIF Rb clock. Suggestions are made for improving estimator performance.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2002
Accession Number
ADA485530

Entities

People

  • Chi‐Chin Wu
  • V. Nuth
  • W. A. Feess

Organizations

  • The Aerospace Corporation

Tags

Communities of Interest

  • Space

DTIC Thesaurus Topics

  • Abstracts
  • Accuracy
  • Artificial Satellites
  • Clocks
  • Electronic Mail
  • Engineering
  • Ephemerides
  • Errors
  • Information Operations
  • Kalman Filters
  • Navigation
  • Range Finding
  • Satellite Constellations
  • Spacecraft
  • Statistics
  • Test And Evaluation
  • Time Intervals

Readers

  • Computational Modeling and Simulation
  • Positioning, Navigation, and Timing (PNT) Technology.

Technology Areas

  • Space