Ultratight navigation observation lock detector
AssigneeThe Aerospace Corporation
InventorsWalter Engevald Lillo, Manorama Gollakota Raghavender, John Lukesh, Randal Kirk Douglas
Life of this patent
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Abstract
An observation lock detector receives I and Q correlations and measurement residuals and transforms the I and Q quadrature correlation outputs based upon computed code phase and carrier phase into transformed I and Q quadrature signals communicated to conventional output lock detectors to provide validity and confidence indicator signals for indicating that the residual estimates are valid for dynamic propagation of the residuals in a navigation receiver for improved performance especially in low signal-to-noise environments such as for use in an ultratight GPS navigation system.
Claims18
A part of a navigation system comprising,
- a navigation processor operative to receive signals derived from an antenna,
- the navigation processor adapted to implement a detector,
- the detector for receiving quadrature correlations and residuals generated from the quadrature correlations, the detector for providing validity indicators indicating the validity of the residuals,
- the detector comprising,
- a maximizer for receiving the quadrature correlations and the residuals and generating a code phase offset, the maximizer for combining the quadrature correlations into combined correlations using the code phase offset,
- a rotation matrices generator for receiving the residuals and generating a carrier phase angle offset,
- a rotator for rotating the combined correlations by the carrier phase angle offset into transformed correlations, and
- a lock detector for receiving the transformed correlations and for providing a validity indicator indicating validity of at least one of the residuals.
A part of a navigation system comprising,
- the navigation processor operative to receive signals derived from an antenna,
- the navigation processor adapted to implement a detector,
- the detector for receiving quadrature correlations and residuals, the detector for providing indicators indicating validity of the residuals, the detector comprising,
- a maximizer for receiving the quadrature correlations and the residuals, the maximizer for determining a code phase offset, the maximizer, weighting by the weights the quadrature correlations into weighted correlations, that are combined into maximized correlations,
- a rotation matrices generator for receiving the residuals and determining a carrier phase offset angle for generating rotational matrices,
- a rotator for rotating the maximized correlations into transformed correlations, and
- lock detectors for receiving the transformed correlations and providing the indicators.
A part of a navigation system comprising,
- a navigation processor adapted to implement a detector,
- the detector for receiving quadrature correlations and residuals generated from the quadrature correlations, the detector for providing validity indicators indicating the validity of the residuals,
- the detector comprising,
- a maximizer for receiving the quadrature correlations and the residuals and generating a code phase offset, the maximizer for combining the quadrature correlations into combined correlations using the code phase offset,
- a rotation generator for receiving the residuals and generating a carrier phase angle offset,
- a rotator for rotating the combined correlations by the carrier phase angle offset into transformed correlations, and
- a lock detector for receiving the transformed correlations and for providing a validity indicator indicating validity of at least one of the residuals.
Dependencies are inferred from the claim text.