USCG NAVIGATION CENTER

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USCG NAVIGATION CENTER

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

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Topics

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

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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

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GPS Space and ControlClock and Reaction Wheel
Performance Status(as of 22 Nov 2004)
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GPS Positions 22 November 04
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Constellation Performance

• 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)

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.
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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.

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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.

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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.

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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.

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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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NAVCEN Web Site

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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.

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DGPS
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Current NDGPS Coverage
In the lower 48, approximately 87 has single
coverage and 55 has dual coverage.
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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

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Acceptance of the international standard is
leading to a seamless worldwide service.
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High Accuracy NDGPS
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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

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• Navigation Information Service
• http//www.navcen.uscg.gov
• http//www.navcenter.org (mirror site)
• E-mail nisws_at_navcen.uscg.mil
• Phone [phone]
• Fax [phone]

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