Modern Loran Receivers: Current Performance and Future Enhancements by Linn Roth, Ph'D' Locus, Inc' - PowerPoint PPT Presentation

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Modern Loran Receivers: Current Performance and Future Enhancements by Linn Roth, Ph'D' Locus, Inc'

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Title: Modern Loran Receivers: Current Performance and Future Enhancements by Linn Roth, Ph'D' Locus, Inc'


1
Modern Loran Receivers Current Performance and
Future Enhancementsby Linn Roth, Ph.D.Locus,
Inc.
Some of the data and work reported here was
supported under subcontract SK-00-18 between
Locus, Inc. and Advanced Management Technology,
Inc. under primary Federal Aviation
Administration Contract DTFA01-98-C-00061. Locus
gratefully acknowledges the support of Mitchell
J. Narins of the FAA.
2
Modern Loran Receivers Current Performance
3
Modern Loran Receivers vs 1990 Technology
Receivers. Example Differences
  • DSP-based vs combined analog/digital technology
  • All-in-view (40 stations) vs single chain
  • 24dB improvement in SNRs
  • 1 nS TD resolution vs 100 nS
  • Substantially better
  • - availability and coverage
  • - dynamic performance
  • - absolute and repeatable accuracy
  • Ability to demodulate GPS messages
  • Use of H-field antennas
  • Other improvements in related technologies,
  • e.g. computer modelling of ASFs

4
Antiquated Loran Infrastructure Control Currently
Limits Loran System Performance
  • Modern Receiver Resolution Identifies Timing
    Control Problems
  • USCG Currently Modernizing Infrastructure

5
Example Accuracy with Current Infrastructure
  • 60 hours data
  • Least squares fit from 12 - 18 stations
  • Clusters suggest stability possible with modern
    infrastructure

6
FAA Tech Center Flight Tests - August 2001
  • Compare all-in-view Loran technology to GPS and
  • legacy Loran receiver technology E-field
    antennas

7
FAA Tech Center Data Sacramento AirportClose-up
View of Landing and Takeoff
GPS and SatMate only no SatMate ASF Corrections
8
FAA Tech Center Data Sacramento AirportClose-up
View of Landing and Takeoff
SatMate and Legacy Receivers
9
FAA Tech Center Data Atlantic City, NJ
AirportClose-up View of Aug. 20 Takeoff and
August 28 Landing
GPS and SatMate only no SatMate ASF Corrections
10
Derivation of Quasi-ASFs and Example
Application to Flight Data
  • On August 21, 2001, recorded GPS and SatMate
    data for
  • 90 seconds at single airport location, then
    calculated
  • position offset between GPS and Loran
  • Measured SatMate TOAs were subtracted from the
  • calculated TOAs to obtain ASFs for the
    individual
  • stations used in the navigation solution - here
    11 stations
  • These 11 ASF corrections were applied to SatMate
    data
  • from return flight landing on August 28, 2001
  • A plot of the August 28 data using these
    week-old ASF
  • corrections was created

11
Example SatMate Quasi-ASF ResultsClose-up of
Atlantic City Airport
GPS and SatMate SatMate with Quasi-ASF
Corrections
12
Modern Loran Technology H-field AntennasE-field
H-field
SNR
ECD
  • Higher signal levels and SNRs, lower ECDs
  • Immunity to P-static interference

13
H-field Tests April 30, 2002
14
H-field mount under Saratoga

15
SatMate 1020 Tests, H-field Antenna
  • 5/1/02 flight tests with Ohio University in
    Madison, WI
  • Included 10 ILS-guided approaches
  • WAAS GPS - Green SatMate - Black
  • Simultaneous recording, positions updated 1/sec
  • SatMate 1020 using quasi-ASFs

16
SatMate 1020 Tests, H-field Antenna
  • 3 representative examples of ILS-guided
    approaches
  • SatMate 1020 using quasi-ASFs generated 8
    miles from airport
  • SNRs 5-10 dB lower than expect to achieve
  • Results will improve with
  • - better transmitter control, airport-generated
    ASFs
  • - improved receiver software and antenna hardware

17
SatMate 1020 Tests, H-field Antenna
Run 9
Run 8
Run 7
  • 3 representative examples of ILS-guided
    approaches
  • SatMate 1020 using quasi-ASFs generated 8 miles
    from airport
  • SNRs 5-10 dB lower than expect to achieve
  • Results will improve with
  • better transmitter control, airport-generated
    ASFs
  • improved receiver software and antenna hardware

18
Same 10 ILS Guided Approaches, No ASFs
19
Modern Loran Receivers Future Enhancements
20
Evolution of all-in-view DSP receiver and
H-field antenna a. Reduce size 75 to Eurocard
format b. Develop ARINC 429 Interface c.
Incorporate WAAS message demodulation c. Develop
combined GPS/Loran antenna d. Integrate Loran
receiver into multimode GPS avionics system
for prototype testing
21
SatMate Size Reduction
  • New, all-in-view receiver board will be 100 x
    160 mm
  • Standard ARINC 429 and RS-232 interfaces for
  • integration with GPS

22
Prototype MMR For FAA GPS/Loran
  • Locus-developed Loran card embedded into Rockwell
    Collins MMR
  • For FAA demo/evaluation purposes, independent
    Integration Processor will be inserted to
    minimize development risk
  • WAAS message data demodulated in Loran feeds into
    GPS

23
Combined GPS/Loran Antenna
  • Loran H-field 130mm x 130mm x 50 mm
  • GPS microstrip patch
  • Prototype now operational

24
Preliminary Conclusions
  • Modern all-in-view Loran receivers provide
    substantially
  • better performance than legacy receivers
  • Modern H-field antennas provide many performance
    and
  • size advantages
  • USCG modernization of the Loran infrastructure
    will
  • improve overall system performance even more
  • As demonstrated by many, a combined GPS/Loran
    system
  • offers better performance (e.g. availability,
    continuity, etc.)
  • than either system alone
  • Modern Loran technology is evolving to make
    integration
  • with GPS a reality

25
Modern Loran Receivers Current Performance and
Future Enhancementsby Linn Roth, Ph.D.Locus,
Inc.
Some of the data and work reported here was
supported under subcontract SK-00-18 between
Locus, Inc. and Advanced Management Technology,
Inc. under primary Federal Aviation
Administration Contract DTFA01-98-C-00061. Locus
gratefully acknowledges the support of Mitchell
J. Narins of the FAA.
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