Greater than 25 meters areas of increased error form

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Unformatted text preview: del - Global Average Ionosphere Model - Worst Site 7.00 14.40 1.30 Figure A-5-12. Elements of SPS User Range Error Single vs Dual-Frequency URE as Function of Latitude and Longitude 8 June 2000 RMS URE (meters) 12 Dual Single Frequency Frequency Global Average RMS URE: 1.7 m 7.3 m Worst Site RMS URE: 2.3 m 14.6 m Best Site RMS URE: 1.4 m 2.2 m 10 8 6 4 Single-Frequency RMS URE 2 Dual-Frequency RMS URE 0 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 - Analysis conducted using 1-minute samples over 24 hour sample interval 10 8 - UREs included errors from the following sources: 6 4 ----- 2 0 -180 ANALYSIS NOTES 10 20 30 40 50 60 70 80 90 Latitude (Degrees South to North) -135 -90 -45 0 45 90 135 Signal-in-space clock, orbit, C/A bias Single-frequency model Troposphere Receiver noise 180 Longitude (Degrees Relative to Greenwich) Figure A-5-13. Dual versus Single-Frequency URE Behavior Page A-32 October 2001 GPS SPS Performance Standard Figure A-5-14. Single-Frequency 95% Horizontal Errors over 10 meters – 8 June 2000 Figure A-5-15. Single-Frequency 95% Vertical Errors over 25 meters – 8 June 2000 Page A-33 October 2001 GPS SPS Performance Standard Cumulative Global Distribution of Site 95% Accuracy Performance 8 June 2000 100% 95% Horizontal Cumulative Probability Density Percentage of Earth's Surface 90% 80% 95% Vertical Cumulative Probability Density 70% 60% ANALYSIS NOTES 50% 40% 30% 20% 10% - All-in-View Position Solution - 5 Degree Mask Angle - Sampled every minute over 24 hour sample interval - Global grid of 1,666 points equidistantly spaced - Single-frequency error modeled using AFWA PRISM model database and ICD200 single-frequency algorithm 95% of the Earth had better than 29 meters 95% Single Frequency Vertical Performance 95% of the Earth had better than 16.4 meters 95% Single Frequency Horizontal Performance 0% 0 5 10 15 20 25 30 35 40 Horizontal/Vertical 95% Error over 24 Hours (meters) Figure A-5-16. Cumulative Global Distribution of Site 95% Accuracy Performance In the absence of relatively stronger concentrations of electrons found around the geomagnetic equator, middle (geomagnetic) latitude performance is affected most significantly by disturbances in the Earth’s magnetic field. Accuracy is not normally significantly affected at higher latitudes. The primary concern at higher latitudes is impacts to service availability, due to the possibility of scintillation brought on by an influx of energetic solar particles. Examples of individual site horizontal and vertical performance impacts due to single-frequency model errors are provided in Figure A-5-17 and Figure A-5-18. These figures illustrate singlefrequency user performance at the worst-case site anywhere in the service volume on 8 June 2000. Comparison Comparison of All-in-View Single and Dual-Frequency Horizontal Errors Worst Single-Frequency Performance Location, 8 June 2000 LOCAL MIDNIGHT 30 ANALYSIS NOTES - Worst Location on 8 June 2000 for All-in-View Solution: Horizontal Error (meters) 25 20...
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This document was uploaded on 09/26/2013.

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