159421 119910 93112 a2 00078 0921 4414e 07 26559861

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Unformatted text preview: 091 -95.396 -120.109 4.019 C1 C2 C3 C4 0.0070 0.0013 0.0096 0.0116 0.257 -0.176 0.329 0.360 -4.649E-07 -4.741E-07 -4.689E-07 -4.643E-07 26,559,448 26,559,760 26,561,731 26,558,980 -76.845 -79.314 -78.586 -78.608 -134.773 46.897 47.657 -118.173 58.320 137.004 105.084 170.858 D1 D2 D3 D4 0.0092 0.0024 0.0124 0.0052 2.505 -1.043 2.378 1.931 -4.315E-07 -4.649E-07 -4.335E-07 -4.374E-07 26,559,614 26,559,322 26,560,253 26,558,804 -15.094 -19.249 -11.104 -15.848 -97.275 -163.471 173.130 -30.998 44.798 -119.765 35.480 11.065 E1 E2 E3 E4 0.0025 0.0166 0.0041 0.0149 0.956 1.888 1.914 2.065 -4.748E-07 -4.656E-07 -4.669E-07 -4.643E-07 26,560,183 26,559,896 26,560,112 26,559,478 42.858 43.112 42.769 45.477 129.677 -144.564 -1.198 -107.795 -119.734 -100.752 -119.546 -106.857 0.0077 1.074 -4.649E-07 26,560,817 F1 0.0123 1.259 -4.623E-07 26,558,930 F2 0.0022 1.328 -4.623E-07 26,541,449 F3 0.0049 1.091 -4.636E-07 26,559,765 F4 NOTE (1): δi is relative to 0.30 semi-circles (54 degrees) 101.437 103.077 102.760 104.050 -108.860 8.663 -30.390 -99.324 159.710 149.701 -51.701 46.950 Note that the constellation defined in Table A-2-2 represents the current “nominal” constellation only as of the identified epoch, although the target GLANs are as mentioned previously maintained for a one-year period. Figure A-2-1 illustrates how individual satellites are tracked against their respective GLAN targets to support stationkeeping maneuver planning. Note that insertion of new satellites into primary constellation slots will obviously change the nominal characteristics for that slot. Page A-7 October 2001 GPS SPS Performance Standard 44 Figure A-2-1. Predicted GPS Constellation Geographic Longitude of Ascending Node Behavior (Courtesy 2SOPS) An example of the type of analysis required to ensure new slot definitions conform to the Position Dilution of Precision (PDOP) optimization criterion is presented in Figure A-2-2. All-in-view position solution PDOP values are provided in comparison with the best four-satellite position solution PDOPs. The all-in-view PDOP values were provided to illustrate the fact their availability is always slightly better than the four-satellite PDOP values. 100.0% 99.5% 99.0% 98.7% 98.5% 98.0% All-in-view NAVSOL PDOP Availability 98.4% Best Four NAVSOL PDOP Availability 10-17 25-29 22-31 22-25 4-7 11-20 2-26 5-9 20-25 17-25 7-20 2-11 3-31 21-29 11-31 2-20 1-20 1-25 7-11 97.5% 11-25 PDOP Availability (6 or less) Best Four-Satellite vs All-in-View Global PDOP Availability 20 Worst Case Combinations of Two Satellites Out GPS PRNs Removed Figure A-2-2. Example of Current Global PDOP Optimization Criterion Analysis A-2.1.3 Placement and Usage of On-orbit Spares The GPS constellation is currently designed and optimized for 24 satellites. In an effort to guard against satellite failures and maintain a high probability of all 24 slots being populated, the U.S. Government may launch satellites into planes that are already fully populated. The criteria for Pa...
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This document was uploaded on 09/26/2013.

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