Horizontal geometry as latitude increases however

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Unformatted text preview: sample intervals - One minute sample steps - All-in-view ensemble averaging from known location - SPS signal-in-space UREs, with 50 cm of added noise to represent uncertainty due to Tgd - Five degree mask angle - Statistics are result of empirical sorts for each location over the global grid 95% Error (meters) 6 5 4 3 2 95% Vertical Error 1 95% Horizontal Error 0 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 Latitude (Degrees South to North) Figure A-5-1. Example of GPS SPS Position Accuracy as Function of Latitude GPS Position Accuracy as Function of Longitude 1 June 2000 6 ANALYSIS CONDITIONS - Analysis conducted under normal constellation operational conditions - NANUs applied over intervals defined by 2 SOPS - Global 2 x 2 degree grid (10,356 locations) - 24 hour sample intervals - One minute sample steps - All-in-view ensemble averaging from known location - SPS signal-in-space UREs, with 50 cm of added noise to represent uncertainty due to Tgd - Five degree mask angle - Statistics are result of empirical sorts for each location over the global grid 95% Error (meters) 5 4 3 2 95% Vertical Error 1 95% Horizontal Error 0 0 45 90 135 180 225 270 315 360 Longitude (Degrees East) Figure A-5-2. Example of GPS SPS Position Accuracy as Function of Longitude A-5.2 SPS SIS Accuracy Variation with Two Satellites Out Global 95% accuracy for current operations does not change significantly as a function of two satellites being removed from service, as can be seen in Figure A-5-3 and Figure A-5-4. Worstcase site performance can vary considerably as would be expected, but is still well below the accuracy performance standard values. Page A-26 October 2001 GPS SPS Performance Standard Worst 20 Cases of Two Satellites Out -- Horizontal 95% Error Example Using Normal Ops URE Performance 95% Horizontal Error (meters) 25 ANALYSIS CONDITIONS 95% Horizontal Error Global Average 20 - Current Operations Nominal 24 Satellite Constellation (as of 19 June 2000) 95% Horizontal Error Worst Site 15 - 2 x 2 degree global grid spacing with one minute sample steps over 24 hours 10 - All-in-view position solution with five degree mask angle 5 - Actual NAVSOLs using MCS estimates of instantaneous UREs from 19 June 2000 9-11 10-25 1-25 4-26 17-25 25-26 24-26 4-11 17-26 11-26 2-26 11-31 2-11 10-24 4-24 10-26 9-26 11-20 20-25 11-25 0 GPS Satellite PRN Combination Removed Figure A-5-3. Worst-Case Horizontal Performance with Two SVs Out, Current Ops URE Worst 20 Cases of Two Satellites Out -- Vertical 95% Error Example Using Normal Ops URE Performance ANALYSIS CONDITIONS - Current Operations Nominal 24 Satellite Constellation (as of 19 June 2000) 20 15 - 2 x 2 degree global grid spacing with one minute sample steps over 24 hours 10 - All-in-view position solution with five degree mask angle 5 95% Vertical Error Global Average - Actual NAVSOLs using MCS estimates of instantaneous UREs from 19 June 2000 4-10 8-26 20-25 17-26 3-11 11-26 2-11 10-26 4-9 6-26 9-26 4-26...
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