Global Positioning Systems Wing : GPS IIR-20 (SVN-49) Information.
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Global Positioning Systems Wing : GPS IIR-20 (SVN-49) Information.

Filetype[PDF-575.87 KB]


English
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Details:

  • Alternative Title:
    GPS IIR-20 (SVN-49) Information
  • Creators:
    Goldstein, David
  • Corporate Creators:
    Space and Missile Systems Center (U.S.)
  • Subject/TRT Terms:
  • Resource Type:
    Presentations
  • Geographical Coverage:
    United States
  • Corporate Publisher:
    Space and Missile Systems Center (U.S.)
  • NTL Classification:
    NTL-GEOGRAPHIC INFORMATION SYSTEMS-GEOGRAPHIC INFORMATION SYSTEMS;NTL-SAFETY AND SECURITY-SAFETY AND SECURITY;NTL-PLANNING AND POLICY-PLANNING AND POLICY;
  • Abstract:
    Purpose for this briefing:

    -Discuss SVN-49 signal problem with GPS community

    -Provide information on potential mitigations

    -Present way forward for SVN-49

    Background:

    -SVN-49 unlike other GPS IIR Satellites had L5 R&D Demonstration Payload

    --Demo payload made use of Auxiliary Payload port

    -No impact on L1 and L2 signals was intended or expected

    -“Out of family” elevation angle dependent Pseudo Range Residuals (PRR) seen at monitor stations and by other GNSS users world-wide

    -Root cause studied and established

    --Signals reflecting off L5 filter and transmitted through satellite antenna

    -Result is permanent, static multipath signal within satellite

    -Signal distortion is user elevation angle dependent

    --Little or no distortion at low elevation angle

    -Signal distortion impacts receivers differently depending on unique designs

    -Non IS-GPS-200 compliant receivers greatly complicate the issue

    -Varying impacts prevent a single solution for all forms of user equipment

    Current Status:

    -SVN-49 set unhealthy but still operated as part of GPS constellation

    -Control segment parameters temporarily adjusted to allow 2SOPS to continue to include SVN-49 in operational constellation (152 meter antenna phase center offset)

    -Will permanently modify Kalman Filter to accommodate SVN-49 without impacting users

    -GPSW and 50 SW exploring additional mitigation steps and eliciting user feedback

    -Potential mitigation steps include

    --Increase SVN-49 User Range Accuracy (URA) – change bits in GPS data message that allow user equipment to de-weight or exclude SVN-49 signals

    --Change SVN-49 PRN code to one outside range used by current user equipment

    --Modify SVN-49 signal configurations to mitigate impact to high precision users

    --Leave vehicle unhealthy but usable by some users by adjusting bits in nav message

  • Format:
    PPT
  • Collection(s):
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