navstar gps constellation status
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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
2
Outline
Launch recommendations Constellation Health Assessment Nav Coverage NAVCEN and Interference Reporting Procedures Constellation Performance and Summary
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
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)
5
- Eclipse window
-Recommended launch window
IIR-15(M)
SVN25 (A2) eclipse season no factor for Sep 06 launch
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
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
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 05SVN 25 last clock
11
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)
12
SVN 39 and 53 out
6 N 128.7 EPDOPmax = 10.33
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
SVN 25 and 39 Out
64 S 95.8 EPDOPmax = 11.65
15
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)
16
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
17
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
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 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).
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
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
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
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
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
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
CGSIC GPS Constellation Status
Thank you
Doug LoudenChief, GPS Liaison, USCG
07 May 2006
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