Ongoing Loran Evaluations at the Federal Aviation Administration
and the US Coast Guard Mitchell J. Narins Systems Engineer Federal
Aviation Administration Navigation Integrated Product Team
International Loran Association Conference Boulder, Colorado 4
November 2003 Slide 2 2 Purpose of the Evaluations To determine
whether an enhanced Loran system can provide the: Accuracy
Availability Integrity Continuity a) to support Lateral Navigation
through all phases of flight including Non-Precision Approach (NPA)
b) to support Harbor Entrance and Approach (HEA) for maritime users
To determine what other ancillary benefits can be derived from the
continued provision of enhanced Loran services e.g., to support
Stratum 1 timing and frequency users To determine if providing
these services via Loran is cost- beneficial (i.e., Benefits/Costs
>1) Slide 3 3 North American Loran System TTX Stations: 11 US, 1
Canadian SSX Stations: 13 US, 4 Canadian LSU Control Stations New
SSX Stations: 1 US First New SSX Station Installation George,
Washington Slide 4 4 Government FAA Navigation and Landing Systems
Engr, AND-740 Navigation and Landing System Architecture, ASD-140
CNS Test and Evaluation, ACB-440 Flight Standards, AFS-400 Aircraft
Certification, AIR-130 Special Programs, AVN-5 US Coast Guard HQ
Aids to Navigation Navigation Center Loran Support Unit Command and
Control Center Volpe National Transportation System Center Program
Participants Slide 5 5 Industry Booz|Allen|Hamilton Free Flight
Systems* Illgen Simulation Technologies, Inc. JJMA Locus, Inc.
Megapulse, Inc. Peterson Integrated Geopositioning Reelektronika*
Rockwell Collins Timing Solutions Si-Tex Marine* WR Systems
Academia Ohio University Stanford University US Coast Guard Academy
University of Rhode Island University of Alaska University of
Wales* *New FY 2003 Team Member Slide 6 6 Loran Program Logo
Collection Booz|Allen|Hamilton Slide 7 7 Team Contributions to ILA
2003 4 November: Loran Integrity Certification Dr. Per Enge,
Stanford University Loran of the 21 st Century CAPT Tom Gunther
(USCG Ret.), Booz|Allen|Hamilton Loran-C Maintenance Support CDR
John Macaluso, Loran Support Unit The Challenge of Finding Your Way
in a World Hostile to Radio Navigation Dr. Durk Van Willigan On-air
with the New Solid State Transmitter CDR Chuck Teaney (USCG Ret.)
WR Systems The Case for Transitioning to Time of Emission Control
in the US CAPT Curt Dubay, USCG Navigation Center Loran Operation
Performance Report LCDR Max Caruso, USCG NavCen Detachment
Supporting the Enhanced Loran-C System LT (jg) Zach Conover, Loran
Support Unit Applications of Differential Loran CDR Doug Taggert
(USCG Ret.), Overlook Systems Differential Loran CAPT Ben Peterson
(USCG Ret.), Peterson Integrated Geopositioning Common-View LORAN-C
for Precision Time and Frequency Recovery Dr. Tom Celano, Timing
Solutions Corporation Predicted Differential Loran Performance in
Boston Harbor Mr. Andre Grebnev, Megapulse, Inc. 5 November: Early
Skywave Propagation Dr. Peter Morris, Northrup Grumman Early
Skywave Examples from PCMS Data CAPT Bob Wenzel (USCG Ret.),
Booz|Allen|Hamilton Mitigation of the Effects of Early Skywave CAPT
Ben Peterson (USCG Ret.), PIG Getting a Bearing of ASF Directional
Corrections CAPT Dick Hartnett, USCG Academy Modelling Loran-C
Envelope-to-Cycle Differences in Mountainous Terrain Dr. David
Last, University of Wales Bangor Summer Vacation 2003 ASF Spatial
Mapping in CO/AR/FL/CA Mr. Greg Johnson, JJMA Analysis of
Groundwave Propagation Effects for Loran RNP 0.3 Dr. Sherman Lo,
Stanford University 6 November Loran-C Band Data Collection Efforts
at Ohio University Mr. Curt Cutright, Ohio University Atmospheric
Noise Analysis Mr. Lee Boyce, Stanford University FAA Tests and
H-Field Antenna to Increase Loran-C Availability During P-Static
Mr. Robert Erikson, FAA Technical Center Integrated GPS/Loran
Navigation Sensor for Aviation Applications Mr. James Doty,
Rockwell Collins Development of an Integrated GPS/LORAN Prototype
Navigation System for Business and General Aviation Applications
Dr. James Davis, Free Flight Systems Integrated GPS/ Loran Sensor
for Maritime Operations Mr. Wouter Pelgrum, Reelektronika On
Non-iterative Loran-C Time Difference to Latitude/Longitude
Converters Dr. Paul Williams, University of Wales - Bangor The U.S.
Loran-C Evaluation Program has much to be proud ofand equally much
to report out at this ILA Conference: Slide 8 8 Loran-C Evaluation
Program FY 1994 Federal Radionavigation Plan (FRP) announced that
Loran-C service would terminate 31 December 2000 Congressional
lobbying (primarily by aviation groups) resulted in budgetary
language to continue system development FY 1997 ($4.6 M)
Congressional Mandate The FY 1997 Congressional budget provided
funds to the FAA for upgrades to the Loran-C navigation system
and... to implement an automatic blink system (ABS). FY 1998 ($3 M)
Congressional Mandate The FY 1998 Congressional budget directed the
FAA to continue Loran-C upgrades initiated in fiscal 97. FY 1999
($7 M) Congressional Mandate The Congressional budget provided
funds to the FAA for further development of the Loran-C navigation
system. Slide 9 9 Loran-C Evaluation Program FY 2000 ($10 M)
Congressional Mandate The Congressional budget provided funds to
the FAA for further development of the Loran-C navigation system.
FY 2001 ($20 M requested, $25 M provided) First year included in
Presidents budget FY 2002 ($13 M requested, $19 M provided) FY 2003
($13 M requested, $25 M provided) FY 2004 ($0 requested, $20M -
$25M expected) Senate (Appropriations Report) raised the level of
funding to $20 Million House (Appropriations Report) raised the
level of funding to $25 Million Awaiting Conference Decision Slide
10 10 A Most Substantial Investment * *Assumes $25 M in FY 04 Slide
11 11 Current US Loran-C Policy While the Administration continues
to evaluate the long-term need for continuation of the Loran-C
radionavigation system, the Government will operate the Loran-C
system in the short term. The U.S. Government will give users
reasonable notice if it concludes that Loran-C is not needed or is
not cost effective, so that users will have the opportunity to
transition to alternative navigation aids. With this continued
sustainment of the Loran-C service, users will be able to realize
additional benefits. Improvement of GPS time synchronization of the
Loran-C chains and the use of digital receivers may support
improved accuracy and coverage of the service. Loran-C will
continue to provide a supplemental means of navigation. Current
Loran-C receivers do not support nonprecision instrument approach
operations. 2001 US Federal Radionavigation Plan Slide 12 12 Volpe
GPS Vulnerability Study The vulnerability study released on 10
September 2001 recognized the potential for Loran-C to be a robust
backup system for GPS navigation and augmentation and timing. In an
effort to provide the greatest benefit to the users, encourage the
development of affordable vehicle-based backup such as GPS/inertial
receivers, and, in the event Loran-C becomes a viable terrestrial
backups to GPS, aviation certifiable Loran-C receivers, and
GPS/Loran-C receivers. Conduct a comprehensive analysis of GPS
backup navigation and precise timing options including VOR/DME,
ILS, Loran-C, inertial navigation systems, and operating systems.
Continue the Loran-C modernization program of the FAA and USCG,
until it is determined whether Loran-C has a role as a GPS backup
system. If it is determined that Loran-C has a role in the future
navigation mix, DOT should promptly announce this to encourage the
electronics manufacturing community to develop new Loran-C
technologies. Slide 13 13 Lorans Potential as a GPS Backup
ParameterLoranGPS Frequency100 kHz1.2-1.5 GHz
PropagationGroundwaveLine of Sight Chief Propagation
ErrorsConductivity, troposphere Iono delay variations* variations
PenetrationWalls, ground, 6' seawaterVery little penetration
ModulationTD + CDSpread spectrum CD CoverageTo ground levelTo
ground level Signal StrengthRelatively highVery low by design
Timing BasisTriple CesiumRubidium at present Tx LocationGround -
stationarySpace - moving Utility: Aviation exampleEn route,
terminal airspaceEn route, terminal airspace Lateral-guided
approachLateral-vertical approach** User communitiesMultiple (air,
land, marine)Multiple ( air, land, marine) * Propagation errors are
affected at different times and places by components of solar
storms * GPS propagation variations are not correlated with Loran-C
propagation errors. ** Vertical-guided "precision" approaches
require WAAS or LAAS augmentations. Slide 14 14 Loran-C Navigation
Current Capabilities/Future Needs*
AccuracyAvailabilityIntegrityContinuity Current Definition of
Capability * (FRP) 0.25 nm (463 m) 0.997 10 second alarm/ 25m error
0.997 FAA NPA (RNP.3) Requirements 0.16 nm (307 m) 0.999
0.99990.99999990.999 - 0.9999 USCG Harbor Requirements (to date)
0.004 - 0.01 nm (8 20 m) 0.997 - 0.999 10 second alarm/ 25m error
0.9985 0.9997 over 3 hours Note: Most stringent requirements shown
in aviation orange. * Includes Stratum 1 timing and frequency
capability. Slide 15 15 Timing User Spectrum 0.1 ns1 ns10 ns100 ns1
s10 s100 s1 ms10 ms100 ms1 s PTTI/R&D - NIF Scientific/
Experimental High Precision Military -GPS Monitor Stations -GPS
Weapons -AT3 Airborne Geolocation Demo -Bistatic Radar -Other
Applications Advanced Comms Power Systems -Fault Location -Phasor
Meas -Data Sharing CDMA2000 - Base Stations Low Precision Military
-Ground Terminals -VHF Special Comms Astronomy Financial
Transactions National Timing Labs Wide Area Data Logging -Seismic
monitoring -Nuclear Blast Detection Digital Time Servers -NTP, etc
Authentication -Internet login Could be served by Enhanced LORAN
(eLoran) Timing user survey not intended to be a complete
representation of all users. Requirements have been generalized and
averaged over user groups Slide 16 16 Frequency User Range 10 -15
VLBI High Precision Military -GPS Monitor Stations -Various
Applications Stratum 1 Comms -Telcos -Military GT -Digital Wideband
Low Precision Metrology -Equipment Calibration CDMA2000 - Base
Stations Low Precision Military -Combat Control Systems Misc
-Broadcast TV -Digital Modular Radio -IEEE P802.16 Wireless 10 -14
10 -13 10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5
Oscillator Manufacturers -Cal of low-cost xtal Could be served by
eLORAN High Precision Metrology -Equipment Calibration National
Timing Labs Frequency user survey not intended to be a complete
representation of all users. Requirements have been generalized and
averaged over user groups Slide 17 Status of the Ongoing Loran
Evaluation and Associated System Recapitalization Final Report due
to the Departments of Transportation and Homeland Security March
2004 Accuracy Availability Integrity Continuity Slide 18 18 Loran
Evaluation Activities To determine Loran Accuracy Potential: ASF*
studies and calibration (for both conductivity and terrain)
Receiver/Integrated receiver studies Loran Accuracy Performance
Panel (LORAPP) Differential Loran study To determine Loran
Availability Potential: H-Field Antenna/P-static testing CONUS
All-in-view receiver analysis Noise analysis SSX and TFE
modification evaluations To determine Loran Integrity Potential:
Loran Integrity Performance Panel (LORIPP) Time of Transmission/ASF
studies To determine Loran Continuity Potential:
Receiver/Integrated receiver/antenna studies *additional secondary
factors Slide 19 19 Loran Issue 1: Accuracy Current Accuracy: 0.25
nm, 2drms, 95% Target Accuracy (NPA): 0.16 nm (307 m) - RNP 0.3
0.43 nm (802 m) - RNP 0.5 Target Accuracy (HEA): 8 20 m, 2drms, 95%
IssuesPotential Mitigations Old timing sources New cesium clocks
Old timing equipment New timing suite Tube technology Solid State
Transmitter (SSX) technology Simple propagation model New ASF*
tables/algorithms No real-time corrections LORAPP (Differential
Loran) *additional secondary factors Slide 20 20 Flights to Support
Characterization of ASFs August 2002 and March 2003 Slide 21 21
Typical Results Loran 7 Loran 1 GPS 1 Loran 8 GPS 7 GPS 8 ~13.0 m
~3.0 m ~2.0 m Loran 2 Loran 7 GPS 2 Loran 3 GPS 7 GPS 3 ~9.0 m ~6.0
m ~6.5 m NPA Requirement: 307 m! Slide 22 22 Flights to Support
Characterization of ASFs July September 2003 Slide 23 23 Loran ASF
Measurement Campaign Lots of Miles Lots of Data Monterey,
CaliforniaPensacola/Destin, Florida Grand Junction, Colorado Little
Rock, Arkansas Slide 24 24 Loran Issue 2: Availability Current
Availability: 0.997 Target Availability (NPA): 0.999 - 0.9999
Target Availability (HEA): 0.997 0.999 IssuesPotential Mitigations
Precipitation Static H-Field Antenna* Atmospheric Noise H-Field,
AIV Receiver Loss of Station Power UPS Lightning New Lightning
Protection Chain/Stick Availability All-in-view receivers Tube
overloads Solid State Transmitters *Awaiting safety certification
Slide 25 25 Loran Issue 3: Integrity Current Integrity: 10 sec.
alert @ + 100ns or other specified error conditions Target
Integrity (NPA): 0.9999999* 556m HPL, 10 sec. alert Target
Integrity (HEA): 0.99997** IssuesPotential Mitigations Presumed
Integrity/ Loran Integrity Panel (LORIPP) Auto Blink System Loran
Accuracy Panel (LORAPP) *For Aviation: The probability of providing
Hazardous or Misleading Information (HMI) is 1 x 10 -7 **For
Maritime: The probability of providing Hazardous or Misleading
Information (HMI) is 3 x 10 -5 Slide 26 26 Loran Issue 4:
Continuity Current Continuity: 0.997 Target Continuity (NPA): 0.999
- 0.9999 Target Continuity (HEA): 0.9985 0.9997 IssuesPotential
Mitigations Same as Availability plus: Receiver acquisition time
New DSP technology New SSX Switch Units AIV/Integrated Receiver
Slide 27 27 Prototype Brassboard Locus Loran Card Installed in
Rockwell Collins Multi-Mode Receiver Flight Testing Results will be
reported out on Thursday Integrated GPS/Loran receiver for general
aviation also being developed by Free Flight Systems and Locus
Slide 28 28 FreeFlight/Locus GA Multi-Mode Receiver Similar to
GPS/WAAS/Loran MMR development Phase I Prototype testing of
Integrated GPS/WAAS/Loran receiver testing to commence this fall
Slide 29 29 FreeFlight/Locus GA Multi-Mode Receiver Phase II
Prototype to be available for testing Spring 2004 Slide 30 30
Megapulse/Reelektronika/Si-Tek Multi-Mode Marine Receiver Front End
& ADC 77 x 47 mm Signal Processor 77 x 51 mm Slide 31 The Loran
Decision Process Final Report due to the Departments of
Transportation and Homeland Security March 2004 What are we doing?
When are we doing it? When will we be finished? When will there be
a decision? Slide 32 32 The Loran Decision Process 1. Determine if
Loran can provide the accuracy, availability, integrity, and
continuity to support non-precision approach for aviation and
harbor entrance and approach for maritime. 2. Determine if Loran
can provide benefits to timing and frequency users. 3. Determine if
Loran can provide navigation, timing, and frequency benefits in a
cost effective manner (i.e., B/C >1.0). 4. Review results of
evaluation and make recommendation to Secretary of Transportation.
5. Announce US Govt Decision regarding future of Loran. 1. Loran
Evaluation Team will provide report to the Department of
Transportation NLT 31 March 2004. 2. Loran Evaluation Team will
provide report to the Department of Transportation NLT 31 March
2004. 3. Loran Evaluation Team will provide report to the
Department of Transportation NLT 31 March 2004. 4. Positioning and
Navigation (PosNav) Committee of the Department of Transportation
5. Secretary of Transportation Action Responsibility Slide 33 33
The Loran Decision Process Loran Evaluation Team compiles technical
findings and BCA Data into Draft Report December 2003 LORIPPLORAPP
VolpeFAATC Internal FAA Review Internal USCG Review Loran
Evaluation Team compiles comments into Final Report March 2004
PosNav Committee members review the report PosNav Committee meets
to discuss report findings and determine what recommendation should
be forwarded to The Secretary of Transportation Department of
Homeland Security PosNav Committee recommends decision to SecDOT
Secretary of Transportation Announces Decision Slide 34 34
Department of Transportation Pos/Nav Committee Hon. Jeffrey Shane,
Undersecretary of Transportation for Policy, Chairman Members
Federal Aviation Administration Federal Highway Administration
Federal Motor Carrier Safety Administration Federal Railroad
Administration Federal Transit Administration Maritime
Administration National Highway Traffic Safety Administration Saint
Lawrence Seaway Development Corporation Surface Transportation
Board Research and Special Programs Administration US Coast Guard
US Department of Commerce (Geodetic Survey/Weather/Time) US
Department of Defense US Department of Homeland Security (?) Slide
35 35 Summary FY 03 Team continued its excellent progress FY 04
Work continues: Development of multi-mode receivers for aviation
and maritime users Development of ASF models that include spatial
factors based on both conductivity and terrain factors and temporal
factors based on multiple seasonal measurements to support NPA
Design and development of differential Loran system and means to
transmit ASF corrections to users to support HEA Test of
Differential Loran Completion of timing and frequency testing to
determine potential level of support to user communities Completion
of Benefit/Cost Analysis Completion of p-static testing Completion
of LORIPP and LORAPP activities Publication of evaluation report US
Government Loran Decision Slide 36 Questions Slide 37 37 Aviation
Requirements: RNP* 0.3 (target); RNP* 0.5 (minimum) Performance
Requirement Value Accuracy (target)307 meters Accuracy (minimum)802
meters Alarm Limit (target)556 meters Alarm Limit (minimum)926
meters Integrity10 -7 /hour Time-to-alarm10 seconds Availability
(minimum) 99.9% Availability (target) 99.99% Continuity (minimum)
99.9% Continuity (target) 99.99% (Source: FAA Loran Evaluation
Report, June 2002 ) *Required Navigation Performance Slide 38 38
Marine HEA Requirements (Primary) Performance Requirement Value
Accuracy (target)10 meters, 95% Accuracy (threshold)20 meters, 95%
Alarm Limit (target) 25 meters Alarm Limit (threshold) 50 meters
Integrity (target) 3x10 -5 Time-to-alarm 10 seconds Availability
(threshold) 99.7% Availability (target/VTS) 99.9% Continuity
(threshold) 99.85% over 3 hours Continuity (target) 99.97% over 3
hours ( Sources: FRP, DOT Task Force, TASC DGPS Mission Needs
Analysis: Harbor Entrance and Approach, IMO Resolutions A.815(19)
and draft revisions to A.860(20)) Slide 39 39 Marine HEA
Requirements (Backup) Performance Requirement Value Accuracy
(backup)20 meters, 95% Alarm Limit (backup)50 meters Integrity
(target) 3x10 -5 Time-to-alarm10 seconds Availability (minimum)
99.7% Continuity (minimum) 99.85% (over 3 hours) ( Sources: FRP,
DOT Task Force, TASC DGPS Mission Needs Analysis: Harbor Entrance
and Approach, IMO Resolutions A.815(19) and draft revisions to
A.860(20)) Slide 40 40 Performance Specification Value Frequency
Accuracy (threshold) 1 in 10 12 (averaged over 24 hrs) No External
Antenna (desired) Backward Compatibility (desired) Integrity Data
Minimum of USE/NO USE Flag Higher Accuracy Time of Day Time Tag
(Year/DOY/Second) Leap Second information Timing Accuracy
