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
    • Details Supporting Files You May Also Like

    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):
    • Main Document Checksum:
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