1. Status of GPS/Loran Prototype for FAA Trials by James H. Doty and Patrick Y. Hwang, Ph.D., Rockwell Collins, Inc., Linn Roth, Ph.D., Locus, Inc., and Mitchell J. Narins, Federal Aviation Administration, Portions of this work are being performed under subcontract SK-00-18 between Locus, Inc. and Advanced Management Technology, Inc. (AMTI) and under subcontract SK-02-02-001-00 between Rockwell Collins, Inc. and AMTI under a Federal Aviation Administration (FAA) Broad Information Technology Services (BITS) contract.

2. Outline Interest in Loran GPS/Loran Integration Program Program Status Breadboard System design and test results Brassboard System features

3. DOT’s Volpe Center study on GPS vulnerabilities spurred interest in independent, backup systems for both navigation and timing, i.e. critical infrastructure areas USCG interest in harbor entrance and approach FAA interest for NPA (Non-Precision Approach ) Since 1997, Congress has provided $69M to further Loran development, and estimate $21-25M in 2003 Loran infrastructure upgrade well underway, and overall system performance will improve when upgrade complete Resurgence In Loran Interest

4. GPS/Loran Integration Program The FAA is funding efforts to develop resources to evaluate and demonstrate the use of Loran to enhance the integrity and continuity of airborne navigation systems Rockwell Collins and Locus are under subcontracts to Advanced Management Technology, Inc. (AMTI) –Locus is leading the effort to develop a prototype combined GPS & Loran H-field antenna and a standalone Loran receiver –Rockwell Collins is leading the Integration of a Locus Loran receiver into a Collins Multimode Radio (MMR)

5. GPS/Loran Integration Program Locus Rockwell Collins GPS/Loran Antenna Brassboard GPS/Loran Breadboard GPS/Loran Loran Card Standard SatMate 1020 Loran Receiver Standard GNLU-930 MMR Breadboard GLIP Loran Card ICD GLIP Card GPS/Loran Integration Effort GPS/Loran Antenna Development GPS Antenna Requirements H-Field Loran Antenna Loran Receiver

6. Develop Eurocard size SatMate 1030 Develop combined GPS/Loran H-field antenna Support Rockwell MMR integration Deliver prototype systems to FAA and Rockwell and support FAA tests Program efforts began January 2002 Locus : Develop interface definition for embedded Loran card Perform integrity analysis and develop integration algorithms Integrate Locus Loran receiver into Multimode Receiver (MMR) Support Locus antenna integration Deliver prototype system and support FAA tests Program efforts began May 2002 Rockwell Collins : Program Responsibilities

7. Locus Program Status Eurocard SatMate 1030 prototype receiver functioning Combined GPS/Loran prototype antenna functioning Uses certified ADF radome for flight tests

8. Locus Program Status Front Panel Rear Panel Eurocard SatMate 1030 in stand-alone enclosure

9. Rockwell Collins Program Status Breadboard GPS/Loran system completed and van tested GLIP integration processor card for Brassboard System assembled and tested

10. Current Rockwell Collins MMR MMR - GNLU-930 Other GPS users (e.g. FMS, EGPWS) L-band GPS PVT GLS PAN VHF UHF Loc Glideslope ILS loc/glide Localizer/ Glideslope deviations /GBAS C-band MLS az/el Current GNLU-930 MMR provides Localizer/Glideslope deviation information for approach, and PVT (position, velocity, time) information for area navigation and other uses

11. Brassboard MMR Architecture Locus SatMate 1030 Loran card will be embedded into Rockwell Collins MMR An independent GPS/Loran Integration Processor (GLIP) card will be added to minimize development risk MMR - GNLU-930 L-band GLS PAN VHF UHF Loc Glideslope ILS loc/glide Localizer/ Glideslope deviations /GBAS GPS PVT LF Loran Integration Proc. Other GPS users (e.g. FMS, EGPWS)

12. New GPS Loran Integration Processor (GLIP) Functions To facilitate flight test evaluation of alternative Loran utilization techniques, multiple solutions of position and integrity limits are generated and output –“GPS-only” passes through GNSS solution –“Loran-only” recomputes position solution from Loran measurements –“Federated” GPS-Loran processes Loran and GPS measurements but maintains independence between sensors for improved integrity –“Integrated” GPS-Loran calibrates Loran errors using GPS and produces a more accurate position solution GNSSI/O LoranI/O GPS-Only Loran-Only Federated GPS-Loran Integrated GPS-Loran Output I/O ARINC I/O

13. Breadboard GPS/Loran System Takes data from unmodified GNLU-930 MMR and SatMate 1020 Loran Receiver Recreates Loran Position solution from Loran timing measurements Produces an integrated GPS- aided Loran Solution Solutions available on both ARINC 429 and RS232 output formats

14. Breadboard Pallet I/O 110V AC 60 Hz 28V DC Input power Output Data ARINC 1 GPS only ARINC 2 Loran only ARINC 3 GPS/Loran RS232 Combined data for collection Loran H-field Antenna GPS Antenna GPS/Loran Breadboard Antenna Connections The Breadboard GPS/Loran (GPS-aided Loran) solution is a Loran solution corrected with ASFs calibrated using GPS PVT data RS232 output includes ASF correction data, all three position solutions, and raw Loran Data messages

15. Breadboard Loran-Only Position Solution With only three stations weighting does not change position solution With more stations the weighting algorithm has a significant impact on estimated position Revised weighting algorithm overlays Locus solution Extensive work was required to reproduce the Locus position solution from the delta-time measurements –Locus provided implementation details of the Locus weighting algorithm –Position solution differences consistently well under 10 meters Original Collins Weighting No Weighting

16. Breadboard Van Testing The Breadboard GPS/Loran system was tested in the Collins Mobile Navigation Lab Van The antenna mount was raised to reduce interference from other van systems

17. Breadboard Van Test Results The GPS- aided Loran solution is corrected for position bias errors, but has noise characteristics matching the Loran-only solution GPS GPS-Aided Loran Locus Loran Solution GLIP Loran-only 100m

18. Highway Breadboard Van Testing Passed under power lines Start End Turn GPS-aided Loran solution tracked GPS position well except for a brief anomaly when the van passed under high- voltage power lines 1 km

19. Average North Pos. Offset Average East Pos. Offset North Position Noise East Position Noise Locus receiver solution (no ASF corrections) -164.3-195.620.926.6 GLIP Loran-only solution (no ASF corrections) -164.0-196.420.926.8 GPS-Aided solution-2.0-1.418.824.3 Typical Van Test Results Van test solution errors relative to GPS in meters GPS-derived ASF corrections dramatically reduce position error in GPS-aided solution ASF corrections do not significantly reduce noise GPS-aiding Loran corrects slowly-varying ASF errors of Loran but a more tightly integrated solution is required to reduce noise

20. Brassboard System Features The brassboard system will integrate the Breadboard system functionality into the standard GNLU-930 MMR form factor Brassboard will include Locus SatMate 1030 prototype card and Collins GLIP card The integrated solution will be more tightly coupled to GPS to improve noise when GPS is available A new Federated GPS/Loran solution will be added for improved integrity monitoring All outputs will ARINC 429 and RS-232 monitor port will be eliminated

21. Brassboard MMR System Locus Loran card will be installed in place of the MLS slice on door of a modified GNLU-930

22. GLIP Loran MMR – Added Cards The new Collins GPS Loran Integration Processor (GLIP) card will be installed in the center card cluster in place of the FMS slice A ribbon cable from the GLIP to the Loran card will provide power and data communications

23. MMR Card Modifications The ILS and other MMR cards will remain unmodified (except for minor additions to the rear interconnect card) ILS Card Power Supply Rear Interconnect Card System Processor

24. Summary The FAA is supporting efforts to evaluate Loran for suitability of use in NPA and other airborne navigation applications Rockwell Collins and Locus are participating in coordinated programs to develop demonstration prototype GPS/Loran antenna and GPS/Loran MMR –Will be utilized by FAA to evaluate and demonstrate the use of Loran to enhance integrity and continuity The Breadboard GPS/Loran system has been completed and van tested The Breadboard system is working well and performance characteristics are about as expected Components for both the Brassboard System and GPS/Loran Antenna have been assembled and are being tested