1. HONOR-RESPECT-DEVOTION TO DUTY 1 Navstar GPS Constellation Status Navstar GPS Constellation Status 23 May 2006 Doug Louden Chief, GPS Liaison, USCG HQ AF Space Command GPSOC, Civil Analyst Colorado Springs, CO. Peterson AFB (719) 554-3582 Schriever AFB (719) 567-5093 CGSIC

2. 2 Outline Launch recommendations Constellation Health Assessment Nav Coverage NAVCEN and Interference Reporting Procedures Constellation Performance and Summary

3. 3 IIR-(M) Launch Considerations So far, launch considerations: C4 (SVN 53), A2 (next launch, SVN 58) Can re-phase to desired location if launch is within plane

4. 4 GPS IIR/MLV Launch Window Opening Time - 2006 (Descending/Ascending Node Injection) Weather unstable at Cape during Sept 06 launch window for IIR-15(M) IIR-15(M)

5. 5 - Eclipse window -Recommended launch window IIR-15(M) SVN25 (A2) eclipse season no factor for Sep 06 launch

6. 6 Weather/Eclipse Season IIR-15(M) launch in Sep 06 to replace SVN25 at A2 Weather unstable at Cape in Sep 06 for launch to A2 Multiple weather delays with IIR-12 (Jul 04) and IIR-13 (Nov 04) SVN25 at A2 has next eclipse season: mid-June to mid-July 06 SVN25 will go through eclipse before replacement SVN25 eclipse season poses no problem for a Sep 06 launch

7. 7 Launch Recommendations Launch IIR-15(M) to A2 in Sep 06 to replace SVN25 No need to decommission an SV, 29 PRNs in use, 1 is available Launch IIR-16(M) NET Apr 07 Determine IIR-16(M) plane/slot at future date Determine a vehicle to remove from service for PRN prior to IIR- 16(M) launch

8. 8 Glossary Cross-plane back-up: A satellite in the 6 plane constellation providing back-up navigation coverage for a failed satellite in an adjacent plane thereby minimizing the impact of the failure. Close/Distant pairs: The GPS Optimized 24 constellation is a non-symmetric 6 plane constellation. Each plane in the Optimized 24 constellation has four satellites grouped as a close pair (separated by about 30 deg Argument of Latitude) and a distant pair (separated by about 130 deg Argument of Latitude). On-orbit storage: The time between when a satellite or component is launched and when it is initialized and operated. Expandable slot: The B1, D2 or F2 slots of the Expandable 24 constellation which, when “expanded”, forms a “fore” and “aft” slot, straddling the original baseline slot, thus providing an additional close pair and better constellation performance than the 24 + 3. Expanded slot: An expandable slot in the Expandable 24 constellation that has been augmented by an additional satellite and has been slightly rephased so that the new close pair of satellites straddle the original location. Optimized 24 Constellation: The non- symmetric six plane GPS constellation as documented in the currently approved SPS PS. This structure has four satellites per plane grouped as a close pair and a distant pair. Also referred to as the “Baseline 24” constellation. Expandable 24 Constellation: The Optimized 24 Constellation with three expandable baseline slots defined in the B, D, and F planes to create an additional close pair. Also referred to as the “Optimized 27” constellation.

9. 9 Block II Block IIA Block IIR ACBEDF 80 100 120 160 180 0 20 40 60 GLAN (deg) E2 A3 A1 A2 A4 B3 B4 B2 B1 C1 C2 C3 C4 D1 D2 D3 D4 E1 E3 E4 F1 F2 F3 F4 38 27 25 39 30 56 44 35 36 33 59 37 34 61 45 46 40 54 60 43 26 41 15 29 51 Empty Slot 47 53 32 24 GPS Locations 1 Apr 06 (GLAN) IIR-15(M) Block IIR-M Rephase 1 deg day drift 140 37 in April

10. 10 17 (-1) SVs past design life 12 (-1) SVs past pre-launch mean life estimate (MLE) 14 (-1,+1) SVs one component away from nav mission failure 9 (+0) SVs one component away from bus failure Anomaly Summary SVN39 (C5) Clock swap X2 SVN25 (A2) Clock swap (on last clock) SVN30 (B2) Clock swap Constellation Status Health Changes Since Last Year Total SVs in Category SVN 31 disposal 15 Dec 05 SVN 25 last clock

11. 11 MLE: II= 12.05 IIA= 13.03 IIR= 14.18 IIR-M=8.60 yrs MMD: IIF= 11.0yrs Constellation Assessment N:/Althouse/GPS-/Program Summary/Problem Vehicle Listing As Of 1 Apr 06 Design Life: II/IIA - 7.5 yrs IIR - 10 yrs IIF - 15 yrs SVN 00 PRN 00 BUS NAV Clocks Rubidium Cesium 12 34 Good Dead Suspect Unused Clock Status = IIRs : only 3 Rb clocks SVN PRN A B C D E F SVN36 PRN06 SVN 51 PRN 20 SVN 32 PRN 01 SVN 25 PRN 25 SVN 27 PRN 27 SVN 53 PRN 17 SVN 30 PRN 30 SVN 35 PRN 05 SVN 33 PRN 03 SVN 37 PRN 07 SVN 46 PRN 11 SVN 34 PRN 04 SVN 40 PRN 10 SVN 54 PRN 18 SVN 26 PRN 26 M SVN 38 PRN 08 SVN PRN SVN 44 PRN 28 SVN 39 PRN 09 SVN 15 PRN 15 SVN PRN SVN 56 PRN 16 SVN PRN SVN 45 PRN 21 SVN PRN SVN 60 PRN 23 1 2 3 4 SVN 43 PRN 13 SVN 41 PRN 14 SVN 29 PRN 29 SVN PRN SVN 24 PRN 24 SVN 47 PRN 22 SVN 59 PRN 19 SVN 61 PRN 02 SVN PRN Vehicle count: 29 total 1 IIs 15 IIAs 13 IIRs (includes 1st IIR-M)

12. 12 SVN 39 and 53 out 6 N 128.7 E PDOPmax = 10.33

13. 13 SVN 25 Status Age = 14 years Single String in Nav NDU power supply failed 23 Dec 05 Rubidium 1 (last clock) selected 25 Dec 05, performance variable Single String in Bus Operating on three wheels Wheel #3 electronics failed in 2003 Double lubed wheels additional failures unlikely Solar array degradation Currently being power managed High constellation coverage value SVN 32 and SVN 37 will provide cross plane backup SVN25 recommended for replacement by IIR-15(M)

14. 14 SVN 25 and 39 Out 64 S 95.8 E PDOPmax = 11.65

15. 15 Decommissioned/Out-of-Service GPS On-orbit Satellite Predicted Life Remaining (Oct 05 Reliability)

16. 16 Blk II Blk IIA Blk IIR Deactivated Satellite Vehicle Blk IIR-M Years 242528262732293739353436334030433846511544415456454759606153 2 4 6 8 10 Block IIR MLE Block II & IIA MLE 12 14 Block IIR-M MLE (as of: 1 Apr 06) 16 Operational for 4.5 yrs – Used for Test & Checkout GPS Satellite Age Design Life: II/IIA - 7.5 yrs IIR - 10 yrs IIRM - 8.5 yrs IIF - 15 yrs

17. 17 Accuracy Equation Good DOP Poor HDOPPoor VDOP Accuracy = Statistical Conversion * DOP * URE 2 + UEE 2 ~68% (~DRMS) UEE Nav Message ~95% (~2DRMS) 50% (CEP) GA MCS MS Good Moderate Poor 0 1 2 3 4 5 6 DOP True Range Accuracy; DOP is a big part of the accuracy equation URE

18. 18 SPS PS Requirements Sec 3.2, table 3-2: Sec 3.2, paragraph 2: In support of the service availability standard, 24 operational satellites must be available on orbit with 0.95 probability (averaged over any day). PDOP Availability StandardConditions and Constraints ≥ 98% global Position Dilution of Precision (PDOP) of 6 or less ≥ 88% worst site PDOP of 6 or less Defined for position solution meeting the representative user conditions and operating within the service volume over any 24-hour interval. Based on using only satellites transmitting standard code and indicating “healthy” in the broadcast navigation message (sub-frame 1).

19. 19 NAVCEN & Data Broadcasts Subscription services that deliver Operational Advisory Broadcast (GPS Status Messages) and/or the Notice Advisory to NAVSTAR Users (NANU) via List servers. 1. GPS Status List server: This service provides the subscriber with an e-mail containing the newly updated Status Message that is sent by the NAVCEN within 60 minutes of notification by the Air Force of a change to the GPS Constellation. 2. NANU List server: This service provides the subscriber with an e-mail containing the NANU that is sent by NAVCEN within 60 minutes of notification by the Air Force of a change to the GPS Constellation. 3. CGSIC List server: This service provides the subscriber with an e-mail containing GPS and CGSIC announcements.

20. 20 Interference Reporting The Navigation Center appreciates your reports regarding service degradations, outages, or other incidents. Please report problems via our GPS Problem Report Page. After a GPS user completes these forms, they are sent to a database for tracking, analysis, and resolution. Reports may be received via phone/fax.

21. 21 Interference Reporting Process User contacted for additional information, if necessary. If the report is aviation related it will be directed to the FAA for tracking, analysis, and resolution. Maritime and terrestrial related reports will be processed simultaneously by the USCG GPS Liaison to the GPS Operations Center at Schriever AFB and NIS personnel for resolution.  Check for constellation events during reported outage period by using NANU.  Perform analysis of constellation activity during reported outage times.

22. 22 Interference Reporting Process Upon finding a resolution, the NIS will notify the user; if the report is not resolved for 30 days, the user will be notified of the situation. 30 days after reporting findings to the user, the NIS will again contact the user to assess the situation and submit a new report if necessary. Focus is on Customer Service and Satisfaction.

23. 23 Navigation Information Service http://www.navcen.uscg.gov http://www.navcenter.org (mirror site) E-mail: TIS-PF-NISWS@uscg.mil Phone: +1 703 313 5900 Fax: +1 703 313 5920

24. 24 Constellation Summary 29 satellites on-orbit 29 satellites set healthy to users 0 satellites launched(2006) 1 satellites decommissioned 1 satellite disposed (SVN 31) Component changes since Oct 2005 SVN 39 Clock swap: Cs to Rb to Cs SVN 25 Clock swap: (Cs to last Rb) and NDU power supply failure SVN 30 Clock swap: (Rb to Rb) Constellation changes since Oct 2005 SVN 53 operational 16 Dec 05 SVN 37 rephase started Jan 06 arrived target GLAN 27 April

25. 25 Summary and GPS Future Recommendations Launch IIR-15(M) to A2 in Sep 06 to replace SVN25 No need to decommission an SV, 29 PRNs in use, 1 is available (PRN 31) Launch IIR-16(M) NET Apr 07 Determine IIR-16(M) plane/slot in future Determine a vehicle to remove from service for PRN prior to IIR- 16(M) COMPAT test at a future date

26. 26 CGSIC GPS Constellation Status Thank you Doug Louden Chief, GPS Liaison, USCG 07 May 2006