GPS Augmentations and Enhanced GPS Augmentations and Enhanced Loran: Loran: Infrastructure Precision and Infrastructure Precision and Reliability Reliability Asia GNSS Workshop Seoul, Korea - November 4, 2004 James J. Miller DOT Office of the Secretary
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GPS Augmentations and Enhanced Loran: Infrastructure Precision and Reliability Asia GNSS Workshop Seoul, Korea - November 4, 2004
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GPS Augmentations and Enhanced Loran: GPS Augmentations and Enhanced Loran: Infrastructure Precision and ReliabilityInfrastructure Precision and Reliability
Asia GNSS Workshop
Seoul, Korea - November 4, 2004
James J. Miller
DOT Office of the Secretary
Asia GNSS Work Shop – Seoul Nov. 4, 20042
OverviewOverview
GPS Augmentations & ApplicationsGPS Augmentations & Applications Wide Area Augmentation System (WAAS)Wide Area Augmentation System (WAAS) Local Area Augmentation System (LAAS)Local Area Augmentation System (LAAS) Nationwide Differential GPS (NDGPS)Nationwide Differential GPS (NDGPS)
Loran developments in the U.S.Loran developments in the U.S. Loran Today Modernizing Loran Achieving “eLoran”
– 82 sites currently operational - 86 sites by December 2004
Single-station coverage – now 92% of CONUS
– Dual-station coverage currently 50% of CONUS
Nationwide single coverage by end of 2005 with the
addition of 5 more sites
Nationwide dual coverage by end of 2008
– Total of 110 sites in CONUS and 15 sites in Alaska
International Standard used in 40 countries
Asia GNSS Work Shop – Seoul Nov. 4, 200415
International StandardInternational 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
Asia GNSS Work Shop – Seoul Nov. 4, 200416
Current NDGPS CoverageCurrent NDGPS Coverage
Asia GNSS Work Shop – Seoul Nov. 4, 200417
Completed NDGPS CoverageCompleted NDGPS Coverage
Asia GNSS Work Shop – Seoul Nov. 4, 200418
Intelligent Transportation SystemsIntelligent Transportation Systems
• Improved roadway safety
– Minimize accidents
• Crash prevention
technologies research
• Road departure prevention
– Electronic mapping
– High-Accuracy NDGPS
• In-vehicle navigation for
precise position
determination
• Snowplow guidance
Asia GNSS Work Shop – Seoul Nov. 4, 200419
GPS at Work: Snow Plow VideoGPS at Work: Snow Plow Video
Asia GNSS Work Shop – Seoul Nov. 4, 200420
High Accuracy NDGPS Develop a nationwide 3-D dynamic positioning service that
has an accuracy better than 15 centimeter and time to alarm integrity of less than 2 seconds
Coexist with existing NDGPS infrastructure
New Initiatives - AccuracyNew Initiatives - Accuracy
GPS (13-24 meters)
HA-NDGPS Dynamic(0.1 meters)
NDGPS(1 to 3 meters)
Asia GNSS Work Shop – Seoul Nov. 4, 200421
HA-NDGPS StatusHA-NDGPS Status
HA-NDGPS Signal Successfully Broadcast from two locations– Static accuracy at 50 km better than 1cm 3-D– Dynamic accuracy at 250 km better than 20 cm 3-D
• Atmospheric Prediction Algorithms show promise
• Implementation Cost <$100,000 per site
• Benefits of multi-site broadcast
• Additional testing planned over next several months
Asia GNSS Work Shop – Seoul Nov. 4, 200422
High Accuracy - NDGPS PlansHigh Accuracy - NDGPS Plans
Hawk RunHawk Run
MaconMacon
GradyGrady
HackleburgHackleburg BoboBobo
GoodlandGoodland
TopekaTopeka
OnondagaOnondaga
MedfordMedford
EdinburgEdinburg
MedoraMedora
BillingsBillings
Great FallsGreat Falls
PolsonPolson SpokaneSpokane
AppletonAppleton
Klamath FallsKlamath Falls
AustinAustin
BakersfieldBakersfield
EssexEssex FlagstaffFlagstaff
AlbuquerqueAlbuquerque
SummerfieldSummerfield
PuebloPueblo
HudsonHudson FallsFalls
GWEN Sites New Site Coast Guard Site Green - Operating Red – Planned Dark Blue – HA-NDGPS broadcasting Light Blue – HA-NDGPS planned
– Evolve to Enhanced Loran (eLoran) in both CONUS and Alaska
Asia GNSS Work Shop – Seoul Nov. 4, 200428
Legacy LoranLegacy Loran
Loran is currently:– A hyperbolic radionavigation system…
• …operating between 90 kHz and 110 kHz…• …that uses a very tall antenna…• …that broadcasts primarily a ground wave• …at high power…• …that provides both lateral position…• …and a robust time and frequency standard
– A supplemental system for enroute aviation navigation in the U.S. National Airspace System (NAS)
– A system for maritime navigation in the coastal confluence zone (CCZ)
– A Stratum 1 frequency standard (i.e., 1 x 10-11) that also provides time within 100 ns of UTC (USNO)
Asia GNSS Work Shop – Seoul Nov. 4, 200429
As a radionavigation system, Loran provides:
– A predicted 2drms accuracy of 0.25 nm (460 m) and a repeatable accuracy of 60-300 ft (18-90 m)*
– An availability of 99.7% (based on triad operation)*
– A level of Integrity based on exceeding certain operational parameters measured at the transmitters and at system area monitor sites
– Continuity no greater than 99.7% (its availability), but potentially worse depending on receiver characteristics and geometry of the triad being used…
– Loran today does not meet high-performance, precision standards relative to other Nav aids…
* U.S. Federal Radionavigation Plan (FRP)
Legacy Loran Legacy Loran (cont.)(cont.)
Asia GNSS Work Shop – Seoul Nov. 4, 200430
North American Loran SystemNorth American Loran System
Today’s Coverage in North AmericaToday’s Coverage in North America
Asia GNSS Work Shop – Seoul Nov. 4, 200432
“The Government is evaluating the ability of an enhanced Loran system to support non-precision approach for aviation users, harbor entrance and approach for maritime users, and improved performance for time and frequency users.”
“If the Government concludes as a result of the evaluations that Loran-C is not neededis not needed or is not cost is not cost effectiveeffective, the United States Coast Guard (USCG) will plan to disestablish the system by the end of fiscal year 2008 with appropriate public notice.”
Current U.S. Loran PolicyCurrent U.S. Loran Policy
Asia GNSS Work Shop – Seoul Nov. 4, 200433
U.S. DOT Navigation Task Force ReportU.S. DOT Navigation Task Force Report
“If Loran can meet
requirements for non-
precision approach for
aviation users, harbor
entrance and approach for
maritime users, and
improved performance for
time and frequency users,
and is cost effective,
Loran should be included in the future radionavigation mix.”
“The evaluation shows that the modernized Loran system could satisfy the current NPA, HEA, and timing/frequency requirements in the United States and could be used to mitigate the operational effects of a disruption in GPS services...
“…If the decision is made to retain Loran as one of the federally provided radionavigation systems, the extent to which these modifications are accepted and implemented will define the actual characteristics of the resulting enhanced Loran (eLoran) system.”
“Enhanced Loran” means a modernized Loran that meets the current requirements of GPS navigation and timing users and, therefore, can be used as a GPS back-up
Requirements must be met for:– Maritime Harbor Entrance & Approach (HEA)
• Accuracy within 20 meters
– Aviation Non-Precision Approach (NPA)• Probability of Hazardous or Misleading information no greater
than 1 x 10-7 per hour
– Timing• Within 100 nanoseconds of UTC
Enhanced Loran (eLoran) availability:– CONUS by December 31, 2008– Alaska by December 31, 2009
Asia GNSS Work Shop – Seoul Nov. 4, 200436
Loran-C vs. Loran-C vs. eLoraneLoran
The Loran technical evaluation showed that eLoran could meet the aviation requirements for non-precision approach (NPA) and the maritime requirements for harbor entrance and approach (HEA)
0.99999990.9999999(1 x 10-7)(1 x 10-7)0.999 – 0.99990.999 – 0.99990.004 - 0.01 nm0.004 - 0.01 nm
(8 – 20 m)(8 – 20 m)eLoran
10 second alarm/
25 m error0.997
0.25 nm(463 m)Loran-C
IntegrityAvailabilityAccuracy
Asia GNSS Work Shop – Seoul Nov. 4, 200437
Loran Data ChannelLoran Data Channel
Loran must transmit information to users to achieve the accuracy, availability, integrity, and continuity requirements for NPA and HEA
eLoran will transmit this information by adding a 9th Pulse to the Loran transmission
It preserves navigation information on pulses 1-8
Its feasibility has been proven with solid-state transmitters
U.S. has successfully tested its ability to broadcast and receive station ID, integrity, time, and differential messages
Facilitates all-in-view vs. chain operation
Each Loran station becomes essentially a pseudolite
U.S. is planning to activate 9th pulse at Loran Station Seneca, NY and perform additional testing in Boston and New York using differential corrections from several monitors
Asia GNSS Work Shop – Seoul Nov. 4, 200438
Time of Transmission (TOT) ControlTime of Transmission (TOT) Control
Evolving from the current System Area Monitoring (SAM) control to Time-of-Transmission Control is essential to achieving eLoran All of CONUS should be completed by
December 2005, including:• Loran and Control Station electronics modernized • Loran on Time-of-Transmission control implemented• All-in-view/9th pulse receivers development• Differential Loran information developed for specific
harbors
Asia GNSS Work Shop – Seoul Nov. 4, 200439
New Loran Station ElectronicsNew Loran Station Electronics
New Solid State New Solid State Transmitter (NSSX)Transmitter (NSSX)
New Timing & New Timing & Frequency Equipment Frequency Equipment
(NTFE)(NTFE)
Asia GNSS Work Shop – Seoul Nov. 4, 200440
New Control-Station ElectronicsNew Control-Station Electronics
New Loran Consolidated Control New Loran Consolidated Control System (NLCCS)System (NLCCS)
Asia GNSS Work Shop – Seoul Nov. 4, 200441
Differential Loran – Real WorldDifferential Loran – Real World
Prototype became available for testing: Spring 2004
Production units expected: Winter 2004
GPS – WAAS
Asia GNSS Work Shop – Seoul Nov. 4, 200447
New Loran/GPS/WAAS New Loran/GPS/WAAS Megapulse/Reelektronika ReceiverMegapulse/Reelektronika Receiver
85 mm
110 mm
30 mm
Asia GNSS Work Shop – Seoul Nov. 4, 20041
Summary As the global standard for positioning, navigation, and timing, GPSGPS
use continues to grow in all modes of transportation and numerous civil applications
GPSGPS modernization and its augmentations are integral components of the emerging robust and reliable positioning, navigation, and timing (PNT) infrastructure
Modernization of Loran continues as part of the U.S. transportation infrastructure
The decision to continue Loran services in the U.S. is currently under review. A U.S. government decision is pending
GPS augmentations and “eLoran” type systems all have a potential role to play in the radionavigation and positioning mix of the future
Greater PNT capabilities for civil users worldwide Greater PNT capabilities for civil users worldwide
Asia GNSS Work Shop – Seoul Nov. 4, 200449
POINT OF CONTACT INFO.
James J. Miller, Deputy DirectorU.S. Department of Transportation, Office of the