USCG NAVIGATION CENTER

NAVCEN and GPS

CGSIC IISC European Meeting

Prague, Czech Republic

14 March 2005

Rebecca M. Casswell

Chief, GPS Branch

Constellation Status

Interference Reporting

NAVCEN Mirror Site

U.S. NDGPS

Topics

Constellation SummarySince 1 Jan 04

•28 operational on-orbit satellites

• 3 satellites launched

–SVN59(PRN19): 20 Mar 04

–SVN60(PRN23): 23 Jun 04

–SVN61(PRN02): 6 Nov 04

• Next launch- May 2005

2 3 41

SVN (PRN)

2 3 41

Clock*Wheel

* II/IIA = Rb, Rb, Cs, Cs IIR = Rb, Rb, RbDiagonal Line = Unhealthy

launchdate Clock

meets specwatch list

deadunused

in use

Wheelfunctionalwatch listdead

GPS Space and ControlClock and Reaction Wheel

Performance Status(as of 22 Nov 2004)

39A (09) 06/93

25A (25) 02/92

1

2

SLOT

3

4

5

PLANE

A C D E F

38A (08) 11/97

56R (16) 1/03 36A (06) 03/94

33A (03) 03/96

59R (19) 03/04

46R (11) 10/99

17 (17) 12/89

51R (20) 05/00

40A (10) 07/96

26A (26) 07/92

43R (13) 07/97

24A (24) 07/91

41R (14) 11/00

44R (28) 07/00

27A (27) 09/92 35A (05) 08/93 37A (07) 05/93 34A (04) 10/93 54R (18) 01/01

32A (01) 11/92

15 (15) 10/90 29A (29) 12/92

45R (21) 03/03

6

47R (22) 12/03

31A (31) 03/93

30A (30) 9/96

B

60R (23) 06/04

61R (02) 11/04

7

GPS Positions 22 November 04

Block II

Block IIA

Block IIR

EPOCH 1 Jul 93

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

F3F4

38

27

25

39

30

56

44

35

36

33

59

37

34

61

45

46

40

54

60

43

26

41

15

17

29

51

IIR-14

47

31

32

IIR-15

24

Constellation Performance

All Errors Based on Dual Frequency, Signal in Space Only. Information Presented Reflects Data Collected During the Period from January 1, 2004 to

August 31, 2004. Thresholds Provided Reflect Average Location Requirements from SPS Signal Specification Dated October, 2001.

PDOP Availability:• Requirement - PDOP of 6 or Less, 98% of the Time or Better• Actual - 99.98495%

Horizontal Service Availability• Requirement - 95% Threshold of 36 meters, 99% of the Time or Better• Actual – 2.75 meters

Vertical Service Availability• Requirement - 95% Threshold of 77 meters, 99% of the Time or Better• Actual – 3.98 meters

User Range Error• Requirement - 6 meters or Less, Constellation Average• Actual - 1.12 meters (excluding SVN23 anomaly, 1 Jan 04)

Data BroadcastsSubscription 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.

Interference Reporting

The Navigation Center appreciates your reports regarding service degradations, outages, or other incidents or anomalies.

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 User contacted for additional information, if necessary.

The report contains specific data regarding the observed outage, degradation, incident or anomaly.

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 simultaneously processed by the USCG GPS Liaison to the GPS Operations Center at Schriever AFB and NIS personnel for resolution.

USCG/USAF Resolution ProcessCheck for constellation events during reported outage period by

using NANU.

Check Post Assessment PDOP Charts at GPS Operations Center website.

Check DGPS logs for GPS signal anomalies (high pseudo range residual, high position error, high range rate correction, various types of dilution of position, high pseudo range noise) during reported outage times.

GSC Liaison checks for reports from military users during same time period of civilian report.

Perform analysis of constellation activity during reported outage times.

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.

NAVCEN Web Site

NAVCEN Mirror Site

1. http://www.navcenter.org

2. Maintained to disseminate information for GPS, DGPS, and Loran radio navigation systems in the event our main site is unavailable.

3. Fully redundant information - all information and functions that are available on the primary site is available on the mirror site.

4. Hosted off-site with remote access capabilities.

DGPS

Current NDGPS Coverage

In the lower 48, approximately 87% has single coverage and

55% has dual coverage.

In the lower 48, approximately 87% has single coverage and

55% has dual coverage.

International Standard

NDGPS is designed to an international, non-proprietary standard Compliant with RTCM SC-104

and ITU-R M.823 Increases market for manufacturers Enhances Global interoperability

Signal is free to all users 47 other countries operate

systems compatible to ours Resulting in a seamless

international navigation system

Acceptance of the international standardAcceptance of the international standardis leading to a seamless worldwide service.is leading to a seamless worldwide service.Acceptance of the international standardAcceptance of the international standardis leading to a seamless worldwide service.is leading to a seamless worldwide service.

GPS (16-24 meters)

High Accuracy NDGPS

NDGPS(1 to 3 meters)

HA-NDGPSDynamic

(0.1 meters)

High Accuracy NDGPS Program Objectives

Develop a nationwide 3-D dynamic positioning service that has an accuracy of less than 15 centimeter and time to alarm integrity of less than 2 seconds

Coexist with existing NDGPS infrastructure

Do not degrade existing NDGPS

Minimize deployment costs

Navigation Information Service

http://www.navcen.uscg.gov

http://www.navcenter.org (mirror site)

E-mail: nisws@navcen.uscg.mil

Phone: +1 703 313 5900

Fax: +1 703 313 5920