Capt Mike Perz, USAFChief Engineer
GPS Modernization
Navstar Global Positioning System (GPS)
Joint Program OfficeLos Angeles AFB CA
Capt Mike Perz, USAFChief Engineer
GPS Modernization
Navstar Global Positioning System (GPS)
Joint Program OfficeLos Angeles AFB CA
IEEE PLANSSession D4
Monterey, CA28 Apr 2004
IEEE PLANSSession D4
Monterey, CA28 Apr 2004
GPS Modernization Update
2
Constellation StatusGPS IIR and IIF ModernizationControl SegmentNew and Improved Clock and Ephemeris (NICE) Summary
Overview
3
18 Block II/IIA Satellites in Orbit
10 Block IIR Satellites in OrbitLast launch 20 Mar 04 (IIR-11)
SVN59 launched to C3 node, set healthy 05 Apr 0410 of 21 Block IIR satellites availableModernizing 8 Block IIR satellites
Next Scheduled LaunchesJun 04 (IIR-12)Sep 04 (IIR-13)Mar 05 (IIRM-01) – available for launch in Dec04
28 Satellites Set “Healthy”
Constellation Status
4
GPS On-orbit Satellite ReliabilityIncludes Mission IIR-11, IIR-12. SVN-23 Out-of-Service. (Oct 2003 Reliability)
0 1 2 3 4 5 6 7 8 9 10 11 12 13
SVN26SVN32SVN29SVN43SVN41IIR-12
SVN23SVN40SVN51SVN54SVN47SVN24SVN15SVN17SVN34SVN46SVN45SVN37SVN36SVN31SVN33IIR-11
SVN35SVN13SVN30SVN44SVN56SVN25SVN39SVN27SVN38
Years From February 2004
1.0 > Reliability >.75.75 > Reliability >.50.50 > Reliability >.25
A
B
C
D
E
F
Reliability = .75 .50 .25
5
Block IIBlock IIABlock IIR
EPOCH 1 Jul 93February 1, 2004
A CB ED F
0
40
80
120
160
200
240
280
320
Arg. of Latitude(deg)
Equator
E2
A3
A1
A2
A4
B3
B4
B2
B1
C1
C2
C3
C4
D1
D2
D3
D4
E1
E3
E4
F1
F2
F3
F4
GPS Locations
38
27
25
39
30
56
44
35
36
33
31
37
34
24
45
46
40
54
23
32
43
26
41
13
15
17
29
51
IIR-11
IIR-12IIR-13
Watch List47
PotentialExpanded Slots
6
Constellation StatusGPS IIR and IIF ModernizationControl SegmentNew and Improved Clock and Ephemeris (NICE) Summary
Overview
7
Block IIR Modernization
Pre-Modernization
Heritage SignalsL1 C/AL1, L2 P(Y)
Design Life10 Years*
Post Modernization
Modernized SignalsHigher PowerL1 C/A, L2CL1, L2 P(Y)L1, L2 M-CodeL1, L2 Pseudo M-Code
Design Life<10 Years*
*Design Life/MMD analysis under review. Actual heritage design life likely longer than 10 years. Modernized Satellites will have a shorter life than current IIR design.
8
Block IIF Modernization
Pre-Modernization
Heritage SignalsL1 C/A, L2CL1, L2 P(Y)
Design Life15 Years*
1 Rubidium and 2 Cesium Clocks
33 Satellite Production Run
Post Modernization
Modernized Signals **Similar PowerL1 C/A, L2CL1, L2 P(Y)L1, L2 M-Code L5 New Civil Signal
Design Life12 Years*
2 Rubidium Clocks and 1 Cesium
12-16 Satellite Production Run
*Design Life/MMD analysis under review. Modernized Satellites will have a shorter life than current IIF design.**Signal specifics still undergoing changes prior to PDR
9
Estimated Signal Availability
2005 2006 2007 2008 2009 2010 2011 2012 2013
28
24
20
16
12
8
4
0
L2C
L5
~ 2.7 Yrs.
Est
imat
ed N
o. o
f L2C
, L5,
& L
1C G
PS
Sig
nals
2014 2015 2016
L1C
~ 7.7 Yrs.
~ 5 Yrs.
Assumes eight IIR-M satellites and average of
three successful
launches per year
Not Official
10
Constellation StatusGPS IIR and IIF Modernization Control SegmentNew and Improved Clock and Ephemeris (NICE)Summary
Overview
11
GPS Monitor StationsNIMA Monitor Stations
GPS Ground Antennas
• New Master Control Station (NMCS)• Improved operator interfaces• IIR-M and IIF capabilities
• Alternate Master Control Station (AMCS)• Integrated Mission Ops Support Center• Operational Support System• GPS Support Facility
Operational Control Segment Future System Description
• Launch and Early Orbit, Anomaly Resolutionand Disposal Operations (LADO) System
• NIMA Monitor Station interfaces• AFSCN Remote Tracking interfaces• System Simulator
12
Constellation StatusGPS IIR and IIF ModernizationControl SegmentNew and Improved Clock and Ephemeris (NICE) Summary
Overview
13
System Accuracy Improvements
Signal in Space Accuracy
4.64.3
32.7
2.11.8
1.4 1.25 1.10.7 0.6 0.5
0.2
6
01234567
SO
RD
'90 90 92 94 96 97 99
II/IIA
OR
D20
00II/
IIAw
/WA
GE IIF
IIFw
/WA
GE
GP
S II
I'1
0G
PS
III w
/A
OD
<1hr
SORD, ORD, GPS III Timeline
Use
r Ran
ge E
rror
, m
(rm
s)
IIR
IIR
14
NICE ApproachNICE Overcomes Limitations of Current NAV Message
~ 40 cm resolution for legacy NAV messages~ 1 cm resolution for NICE messagesMessage assurance
NICE Accomplishes this by:Shortening the curve-fit intervalTweaking the NAV message
Improving resolution of the LSBsAdding some new second-order terms
Adding the Inter-Signal Corrections (ISCs)Employing FEC, CRC, and SV ID for message assurance
* Not covered in this briefing
15
Initial CNAV Content
Subframe 1• Satellite Clock Offset• Reserved Bits
Subframes 2/3• Satellite Ephemeris
Subframe 4• Iono Model Terms• GPS-UTC Offset• Special Message Text• Almanacs (25-32)• Reserved Bits
Subframe 5• Almanacs (1-24)
Messages 1/2• Satellite Clock Offset• Satellite EphemerisMessage 3• Iono Model Terms• GPS-UTC Offset• Inter-Signal Corrections
Message 4• Almanacs (1-64)
Message 5• Special Message Text
Message 6• Mini-Almanacs (7 per)
16
Constellation StatusGPS IIR and IIF ModernizationControl SegmentNew and Improved Clock and Ephemeris (NICE)Summary
Overview
17
GPS is HealthySatellites lasting longer than expectedFuture launches are being re-phased
Sustaining current GPS service for civil and military users is our first priorityConstellation Modernization efforts proceeding
GPS IIR and IIF modernized signals
NICE providesBetter and additional clock & ephemeris informationInter-signal corrections (ISCs) for new signalsMessage assurancePath to future accuracy improvementsSlightly faster Time-to-First-Fix (TTFF)
Summary
