1. Loran Integrity Performance Panel Scalable Modulation for Loran Sherman Lo, Ben Peterson Second LORIPP Meeting Portland, OR September 23-24, 2002

2. Loran Integrity Performance Panel Outline Purpose of Scalable Modulation Recent History of LDC Means of Implementation Technical and Program Considerations Analysis Tools Final Thoughts

3. Loran Integrity Performance Panel Scalable Loran Data Channel (LDC) Easier to Implement Legacy Compatible Low Data Rate Loran QDemonstrate and Publicize Utility of LDC QCould be used to aid Loran Navigation High Data Rate Loran Provides More Utility QWAAS Broadcast, Aid to Loran Navigation QMay not be Legacy Compatible Can we create a modulation scheme that can be tuned from a low data rate, legacy compatible format to higher data rates? QDesigned into User Receivers – No Need for New Equipment

4. Loran Integrity Performance Panel Recent LDC History Dec. 2000: Discussed Lower Data Rate (170 bps) WAAS as Fallback, Do Full WAAS if possible. 2001: Proof of concept of Full WAAS message @ 1Hz using Intrapulse Frequency Modulation (IFM) QSingle fast rate (dual rated would be much more complex) QLegacy compatible format with some degradation in legacy navigation performance Nov. 2001: Meeting at Megapulse QAgreement on how to implement IFM in SSX QTentative commitment to do project Mar. 2002: Presented options at Loran Murder Board, Legacy Support vs Optimized w/o Support QPPM vs. IFM

5. Loran Integrity Performance Panel Outcome of Loran Murder Board Mar. 2002: Main Issue was Loran’s Ability to meet RNP 0.3. Concern that LDC Complicated WAAS GEO Procurement & Confused Manufacturers No Guidance on LDC, Virtually No Real Development since Murder Board

6. Loran Integrity Performance Panel Scalable Modulation Methods Scalable PPM QPPM does not incur significant costs and technical risk associated with IFM QHigh data rate legacy (timing) receiver compatible may be possible (Not tested) Scalable IFM QBetter performance than PPM QCan be legacy compatible (with degradation) even at high data rates PPM, IFM Combination

7. Loran Integrity Performance Panel Fundamental Trades Depend on Legacy Receiver Support Support All Legacy rcvrs Intrapulse Frequency Modulation (IFM) Support Timing Legacy rcvrs PPM w/ Extra Pulses Support No Legacy rcvrs Pulse Position Modulation (PPM) 2001 Tests based on this assumption Least Mature Concept Similar to earlier, lower data rate schemes Phased implementation possibleHedge against req’ts that we do not yet understand. Best perf. for new users. On-air rcvr testing using operational LORSTAs is possible. Most complex signal format, modulator, & receiver (highest technical risk). $30-40M (ROM) to modify SSX. (international accept.?) May need new spectrum to recover perf. loss. Will need TBD additional pulses increasing energy costs and CRI Cost to legacy users. Need for international coordination. Phased implementation impossible.

8. Loran Integrity Performance Panel Technical Considerations For low data rate, legacy compatible LDC, 4 state IFM is technically better than 3 state PPM Q6 dB greater symbol separation, lower raw error rate QHigher (12/7) data rate enables 1 sec message, data wipeoff prior to CR canceling & navigation QNo leading edge modulation/degradation of legacy performance QHowever, for full bandwidth WAAS, we recommended 8 state PPM w/ no legacy support In earlier efforts, transmitter & receiver code produced by same people and changes in format easily accomplished Desire to get receiver manufacturers building receivers means this no longer true QWe need a signal spec, (at least a draft)

9. Loran Integrity Performance Panel Program Considerations What value does LDC & Scalable LDC have? Q Timing & Loran Integrity Q WAAS/SBAS/GPS Q Will Scalable Version Help with Acceptance? Is a Decision Necessary in Near Future? What is Necessary to Make a Decision? QTechnical Issues QProgram Issues How does this Affect Loran Navigation Analysis?

10. Loran Integrity Performance Panel Analysis Tools are Developed ex. IFM 16 Level Performance

11. Loran Integrity Performance Panel Can Analyze Scalable LDC Ex. Detection of Change

12. Loran Integrity Performance Panel Final Thoughts Do we need to confront the issues that were put on the table at the murder board but left on the table? What analysis can we do (do we need to do) on LDC in terms of Loran Nav? Do we need to decide anything beyond that (for now)? Q LDC Utility, etc. Do we need to do any more beyond that (for now)?