HONOR-RESPECT-DEVOTION TO DUTY

1

Navstar GPS Navstar GPS Constellation StatusConstellation Status

23 May 2006

Doug LoudenChief, GPS Liaison, USCGHQ AF Space Command

GPSOC, Civil AnalystColorado Springs, CO.

Peterson AFB (719) 554-3582Schriever AFB (719) 567-5093

CGSIC

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Outline

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

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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

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0:001:002:003:004:005:006:007:008:009:00

10:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:00

240 260 280 300

Gre

enw

ich

Mea

n T

ime,

hr.

UNSTABLE WEATHER

AT LAUNCH SITE

10 20 31

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10 20 31 10 20 28 10 20 31 10 20 30 10 20 31 10 20 30 10 20 31 10 20 3110 20 3010 20 3110 20 30

0 20 40 60 80 100 120 140 160 180 200 220 320 340 360

UNSTABLE WEATHER AT LAUNCH SITE

0:001:002:003:004:005:006:007:008:009:00

10:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:00

240 260 280 300

Gre

enw

ich

Mea

n T

ime,

hr.

UNSTABLE WEATHER

AT LAUNCH SITE

10 20 31

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10 20 31 10 20 28 10 20 31 10 20 30 10 20 31 10 20 30 10 20 31 10 20 3110 20 3010 20 3110 20 30

0 20 40 60 80 100 120 140 160 180 200 220 320 340 360

UNSTABLE WEATHER AT LAUNCH SITE

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)

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- Eclipse window

-Recommended launch window

IIR-15(M)

SVN25 (A2) eclipse season no factor for Sep 06 launch

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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

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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

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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.

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Block II

Block IIA

Block IIR

A CB ED F

80

100

120

160

180

0

20

40

60

GLAN(deg)

E2

A3

A1

A2

A4B3

B4

B2

B1

C1

C2C3

C4 D1

D2

D3

D4

E1

E3

E4F1

F2

F3

F438

27

25

39 30

56

44

35

36

3359

37

34

61

45

46

40

54

60

43

26

41

15

29

51

Empty Slot47

53

32

24

GPS Locations 1 Apr 06(GLAN)

IIR-15(M)

Block IIR-M

Rephase1 deg day drift

14037 in April

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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 05SVN 25 last clock

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MLE: II= 12.05 IIA= 13.03 IIR= 14.18 IIR-M=8.60 yrsMMD: IIF= 11.0yrs

Constellation Assessment

N:/Althouse/GPS-/Program Summary/Problem Vehicle Listing

As Of 1 Apr 06

Design Life:II/IIA - 7.5 yrsIIR - 10 yrsIIF - 15 yrs

SVN 00

PRN 00

BU

S

NA

V

Clo

cks

RubidiumCesium

1 23 4

GoodDeadSuspectUnused

Clock Status =

IIRs : only 3 Rb clocks

SVNPRN

A B C D E F

SVN36PRN06

SVN 51PRN 20

SVN 32PRN 01

SVN 25PRN 25

SVN 27PRN 27

SVN 53PRN 17

SVN 30PRN 30

SVN 35PRN 05

SVN 33PRN 03

SVN 37PRN 07

SVN 46PRN 11

SVN 34PRN 04

SVN 40 PRN 10

SVN 54PRN 18

SVN 26PRN 26

M

SVN 38PRN 08

SVNPRN

SVN 44 PRN 28

SVN 39PRN 09

SVN 15 PRN 15

SVNPRN

SVN 56 PRN 16

SVN PRN

SVN 45 PRN 21

SVNPRN

SVN 60 PRN 23

1

2

3

4

SVN 43PRN 13

SVN 41 PRN 14

SVN 29PRN 29

SVNPRN

SVN 24PRN 24

SVN 47PRN 22

SVN 59 PRN 19

SVN 61PRN 02

SVNPRN

Vehicle count: 29 total1 IIs 15 IIAs 13 IIRs (includes 1st IIR-M)

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SVN 39 and 53 out

6 N 128.7 EPDOPmax = 10.33

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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)

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SVN 25 and 39 Out

64 S 95.8 EPDOPmax = 11.65

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Mar-06

Mar-07

Mar-08

Mar-09

Mar-10

Mar-11

Mar-12

Mar-13

Mar-14

Mar-15

Mar-16

Mar-17

Mar-18

Mar-19

Mar-20

Mar-21

Mar-22

Mar-23

SVN26SVN29SVN32SVN43SVN41SVN60SVN23SVN40SVN51SVN54SVN47SVN15SVN24SVN34SVN46SVN45SVN61SVN37SVN36SVN33SVN53SVN59SVN35SVN30SVN44SVN56SVN25SVN27SVN39SVN38

Time as of March 2006

1.0 > Reliability >.75

.75 > Reliability >.50

.50 > Reliability >.25A

B

C

D

E

FReliability = 0.75 0.50 0.25

Mar-06

Mar-07

Mar-08

Mar-09

Mar-10

Mar-11

Mar-12

Mar-13

Mar-14

Mar-15

Mar-16

Mar-17

Mar-18

Mar-19

Mar-20

Mar-21

Mar-22

Mar-23

SVN26SVN29SVN32SVN43SVN41SVN60SVN23SVN40SVN51SVN54SVN47SVN15SVN24SVN34SVN46SVN45SVN61SVN37SVN36SVN33SVN53SVN59SVN35SVN30SVN44SVN56SVN25SVN27SVN39SVN38

Time as of March 2006

1.0 > Reliability >.75

.75 > Reliability >.50

.50 > Reliability >.25A

B

C

D

E

FReliability = 0.75 0.50 0.25Reliability = 0.75 0.50 0.25

Decommissioned/Out-of-Service

GPS On-orbit Satellite Predicted Life Remaining (Oct 05 Reliability)

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Blk II

Blk IIA

Blk IIR

Deactivated

Satellite Vehicle

Blk IIR-M

Yea

rs

24 25 28 26 27 32 29 37 39 35 34 36 33 40 30 4338 46 5115 44 41 54 56 45 47 59 60 61 53

2

4

6

8

10

Block IIR MLEBlock II & IIA MLE

12

14

Blo

ck I

IR-M

ML

E

(as of: 1 Apr 06)16

Ope

rati

onal

for

4.5

yrs

– U

sed

for

Tes

t &

Che

ckou

t

GPS Satellite Age

Design Life:II/IIA - 7.5 yrsIIR - 10 yrsIIRM - 8.5 yrsIIF - 15 yrs

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Accuracy Equation

Good DOP Poor HDOP Poor VDOP

Accuracy = Statistical Conversion * DOP * URE2 + UEE2

~68% (~DRMS)

UEE

NavMessage

~95% (~2DRMS)

50% (CEP) GA MCS MS

Good Moderate Poor

0 1 2 3 4 5 6

DOP

TrueRange

Accuracy; DOP is a big part of the accuracy equation

URE

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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 Standard Conditions 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).

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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.

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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.

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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.

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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.

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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

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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

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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

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CGSIC GPS Constellation Status

Thank you

Doug LoudenChief, GPS Liaison, USCG

07 May 2006