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

Details

• Alternative Title:
  GPS IIR-20 (SVN-49) Information
• Creators:
  Goldstein, David
• Corporate Creators:
  Space and Missile Systems Center (U.S.)
• Subject/TRT Terms:
  Communication And Control Global Positioning System Navigational Aids Navigation Systems Satellite Navigation Systems
• 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):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:b7b66cc945523696ee9f33964bd0566621a17c1adf83a8529a4249532e9a7759
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/17591/dot_17591_DS1.pdf
• File Type:
  [PDF - 575.87 KB ]