Navstar gps constellation status
Download
1 / 34

Navstar GPS Constellation Status - PowerPoint PPT Presentation


  • 136 Views
  • Uploaded on

CGSIC. Navstar GPS Constellation Status. 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. 07 May 2006. Outline. Launch recommendations Empirical Clock Data

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Navstar GPS Constellation Status' - diep


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Navstar gps constellation status

CGSIC

Navstar GPS Constellation Status

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

07 May 2006


Outline
Outline

  • Launch recommendations

  • Empirical Clock Data

  • Constellation Health Assessment

  • Nav Coverage

  • NAVCEN and Interference Reporting Procedures

  • Constellation Performance and Summary


Iir m launch considerations
IIR-(M) Launch Considerations

  • So far, launch recommendations:

    • C4 (SVN 53), A2 (next launch, SVN 58)

    • Can re-phase to desired location if launch is within plane


Navstar gps constellation status

GPS IIR/MLV Launch Window Opening Time - 2006(Descending/Ascending Node Injection)

IIR-15(M)

Weather unstable at Cape during Sept 06 launch window for IIR-15(M)


Navstar gps constellation status

IIR-15(M)

- Eclipse window

  • Recommended

  • launch window

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


Navstar gps constellation status

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


Navstar gps constellation status

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 (maybe Nov 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


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.

Glossary


Empirical clock history
Empirical Clock History

  • Recent experience shows IIA rubidium clocks that have been in storage for more than 8 years prior to use have had significantly shorter life times than clocks with less than 8 years of on-orbit storage

  • Clocks listed were turned on after more than 8 years on orbit

    • SVN 25 Rb FS #1 currently on last clock with erratic performance since turn-on

    • SVN 39 Rb FS #1 lasted approx. 50 days

    • SVN 35 Rb FS #2 lasted approx. 128 days

    • SVN 23 Rb FS #1 lasted approx. 48 days

    • SVN 27 Rb FS #2 lasted approx. 16 days

  • Early life failures on cesium clocks have occurred, but there is no obvious relationship between failure and on-orbit storage time

    • General reliability on cesium clocks has been better than rubidium clocks


Ii iia clock history primary slot vehicles 12 years old
II/IIA Clock History Primary Slot Vehicles > 12 years old

  • Empirical clock history may influence expected reliability

SVN 25, 35 and 36 have a high likelihood of failing due to clocks (all are II/IIAs)


Navstar gps constellation status

GPS Locations 1 Apr 06(GLAN)

37

Rephase

1 deg day drift

180

43

F3

36

C1

160

B4

35

51

E1

37 in April

140

30

B2

A1

39

GLAN

(deg)

46

D2

29

120

33

C2

24

59

C3

100

F2

26

B1

56

40

E3

80

D4

34

25

A2

IIR-15(M)

60

61

D1

53

41

F1

C4

54

E4

Empty Slot

40

32

44

B3

E2

47

Block II

A4

27

20

45

D3

Block IIA

60

F4

38

A3

0

Block IIR

15

Block IIR-M

A

B

C

D

E

F


Navstar gps constellation status

Constellation Status Health

Total SVs in Category

Changes Since Last Year

  • 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

SVN 31 disposal 15 Dec 05

SVN 25 last clock


Navstar gps constellation status

1

2

3

4

Good

Dead

Suspect

Unused

Clock Status =

SVN 00

PRN 00

Rubidium

1

2

3

4

Cesium

NAV

BUS

Clocks

Constellation Assessment

As Of 1 Apr 06

A B C D E F

Design Life:

II/IIA - 7.5 yrs

IIR - 10 yrs

IIF - 15 yrs

SVN 51

PRN 20

SVN36

PRN06

SVN 61

PRN 02

SVN 56 PRN 16

SVN 39

PRN 09

SVN 41 PRN 14

MLE: II= 12.05

IIA= 13.03

IIR= 14.18

IIR-M=8.60 yrs

MMD: IIF= 11.0yrs

SVN 30

PRN 30

SVN 33

PRN 03

SVN 47

PRN 22

SVN 26

PRN 26

SVN 25

PRN 25

SVN 46

PRN 11

SVN 38

PRN 08

SVN 43

PRN 13

SVN 44 PRN 28

SVN 59 PRN 19

SVN 40 PRN 10

SVN 45 PRN 21

Vehicle count: 29 total

1 IIs

15 IIAs

13 IIRs

(includes 1st IIR-M)

SVN 34

PRN 04

SVN 54

PRN 18

SVN 60 PRN 23

SVN 35

PRN 05

SVN 27

PRN 27

SVN 53

PRN 17

M

SVN

PRN

SVN

PRN

SVN

PRN

SVN 37

PRN 07

SVN 29

PRN 29

SVN 15 PRN 15

IIRs : only 3 Rb clocks

SVN

PRN

SVN

PRN

SVN 24

PRN 24

SVN

PRN

SVN 32

PRN 01

SVN PRN

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


Navstar gps constellation status

A-Plane Analysis

  • Average vehicle age: 12.13 years

    • SVN25, 27, 38 and 39 all past 7.5 year design life

    • SVN25, 27 and 39 past pre-launch MLE

  • Problem vehicles in primary slots: SVN 25, 27 and 38

    • SVN27 is single string in nav, suspect TT&C, last clock

    • SVN25 solar array degradation, operating on 3 wheels,

      single string nav, last clock

    • SVN38 is single string in TT&C

SVN 25 candidate for IIR-15(M)


Svn 39 and 53 out
SVN 39 and 53 out

6 N 128.7 E

PDOPmax = 10.33

UNCLASSIFIED


Svn 25 status
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)


  • Svn 25 and 39 out
    SVN 25 and 39 Out

    64 S 95.8 E

    PDOPmax = 11.65


    Navstar gps constellation status

    B-Plane Analysis

    • Average vehicle age: 6.14 years

      • Youngest average vehicle age of any plane

      • SVN 30 and 35 past 7.5 year design life

      • SVN 35 past pre-launch MLE

    • Problem vehicles in primary slots: SVN 30, 35 and 56

      • SVN 30 is single string in nav

      • SVN 56 MDU redundancy uncertain

      • SVN 35 operating on last clock

        • Swapped to RFS#1 on 2 Sep 05

    • SVN44 reaction wheel restored with Flight Software Patch

    • Fifth slot vehicle: None

      • Primary Slot for Expanded Constellation


    C plane analysis
    C-Plane Analysis

    • Average vehicle age: 8.34 years

      • ALL SVN’s EXCEPT SVN53 and 59 past design life

      • All SVN’s EXCEPT SVN33, 53 and 59 past pre-launch MLE

    • Problem vehicles in primary slots: SVN36

      • SVN36 is on its last clock

    • SVN31 Disposed

    • SVN37 has multiple component failures; array issues

    • SVN28 maintained by 1 SOPS

      • Non mission capable

    • Re-phasings: SVN37 was rephased to provide cross plane back up of slot A2

    SVN37 on station as of Mid April


    D plane analysis
    D-Plane Analysis

    D

    SVN 61

    g

    y

    SVN 46

    g

    y

    SVN 45

    y

    g

    SVN 34

    g

    g

    SVN 15

    y

    y

    SVN 24

    y

    y

    • Average vehicle age: 8.85 years

      • SVN15, 24 and 34 are past 7.5 year design life

      • SVN15, 24 and 34 are past pre-launch MLE

    • Problem vehicles in primary slots: SVN 45, 46 and 61

      • SVN61 MDU Baseband failure

      • SVN 46 is single string in nav

    • SVN24 is a three-wheeled vehicle operating on last clock

    • Fifth slot vehicle: None


    E plane analysis
    E-Plane Analysis

    • Average vehicle age: 7.6 years

      • SVN40 is past 7.5 year design life

    • Problem vehicles in primary slots: SVN40

      • SVN40 FSDU and NDU are single string

    • SVN23 maintained by 1 SOPS (Non-Operational)

      • Potentially mission capable

    E Plane robust overall


    F plane analysis
    F-Plane Analysis

    • Average vehicle age: 10.82 years

      • SVN26, 29, 32 and 43 are past 7.5 year design life

      • SVN26, 29 and 32 past pre-launch MLE

    • Problem vehicle in primary slot: SVN26

      • SVN26 single string in both bus and nav; solar array degradation

    • Fifth slot vehicle: SVN29

      • Additional DCEA power instability could force disposal

      • Primary Slot for Expanded Slot Constellation

    • Re-phasing: None

    SVN32 acting as cross plane back-up for SVN25 and 36 (operating on last clock since 1996)


    Navstar gps constellation status

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

    Decommissioned/Out-of-Service


    Navstar gps constellation status

    GPS Satellite Age

    (as of: 1 Apr 06)

    16

    Blk II

    14

    Block IIR MLE

    Block II & IIA MLE

    Blk IIA

    12

    Blk IIR

    10

    Design Life:

    II/IIA - 7.5 yrs

    IIR - 10 yrs

    IIRM - 8.5 yrs

    IIF - 15 yrs

    Blk IIR-M

    8

    Operational for 4.5 yrs – Used for Test & Checkout

    Deactivated

    Block IIR-M MLE

    6

    4

    2

    Years

    Satellite Vehicle

    15

    24

    25

    28

    26

    27

    32

    29

    37

    39

    35

    34

    36

    33

    40

    30

    38

    43

    46

    51

    44

    41

    54

    56

    45

    47

    59

    60

    61

    53


    Accuracy equation
    Accuracy Equation

    Poor HDOP

    Poor VDOP

    Good DOP

    Good Moderate Poor

    DOP

    01 2 3 4 5 6

    Accuracy = Statistical Conversion * DOP * URE2+UEE2

    Accuracy; DOP is a big part of the accuracy equation

    URE

    True

    Range

    Nav

    Message

    UEE

    GA MCS MS

    50% (CEP)

    ~68% (~DRMS)

    ~95% (~2DRMS)


    Sps ps requirements
    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).


    Navcen data broadcasts
    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.

    • 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.

    • 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.

    • CGSIC List server: This service provides the subscriber with an e-mail containing GPS and CGSIC announcements.


    Interference reporting
    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.


    Interference reporting process
    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.


    Interference reporting process1
    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.


    Navstar gps constellation status

    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


    Navstar gps constellation status

    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


    Navstar gps constellation status

    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


    Cgsic gps constellation status
    CGSIC GPS Constellation Status

    Thank you

    Doug Louden

    Chief, GPS Liaison, USCG

    07 May 2006