# Presentation: 181171

## USCG NAVIGATION CENTER

**NAVCEN and GPS**
- CGSIC IISC European Meeting
- Prague, Czech Republic
- 14 March 2005
-  Rebecca M. Casswell
- Chief, GPS Branch

**Notes:**
Good morning. 

## Topics

-  Constellation Status
-  Interference Reporting
-  NAVCEN Mirror Site
-  U.S. NDGPS

**Notes:**
I will briefly cover the Constellation status, outline our developing GPS/DGPS Interference Reporting Process, and talk for a minute about the U.S. Differential GPS System

## Constellation SummarySince 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

## GPS Space and ControlClock and Reaction Wheel Performance Status(as of 22 Nov 2004)

- GPS Space and ControlClock and Reaction Wheel Performance Status(as of 22 Nov 2004)

## GPS Positions 22 November 04

## 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 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.

**Notes:**
Subscription services that deliver GPS Status and NANU notifications within 60 minutes of delivery from the USAF.
Presently over 5500 users have subscribed to our GPS status and NANU e-mail lists.

## 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](http://www.navcen.uscg.gov/gps/gpsuserinput.htm)_
- 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.

**Notes:**
We have initiated a new Tracking, Analysis, and Resolution process. Actions are designed to provide users feedback to their reports.

## 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 Process

- Check 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.

**Notes:**
Note the new mirror-site web address. Full redundancy with remote off-site capabilities.

## DGPS

## Current NDGPS 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 standard

**Acceptance of the international standard**
**is leading to a seamless worldwide service.**

## High Accuracy NDGPS

## 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

- 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

**Notes:**
Please feel free to contact the NAVCEN/NIS with questions, comments, suggestions, or concerns. We welcome your input. Thank You.

## Slide 21