1 Overview of Performance Analysis of Alternative Navigation Sherman Lo, Rick Niles

2 Outline Performance Study –Parameterized study allows study of many architectures and equipment performance –Rick will show some first cut test Integrity Study

3 Performance Requirements for Alternate Nav Coverage/Performance study only one part –Test to most stringent performance level (operation supported) –Availability/coverage/accuracy Other performance issues –Integrity/TTA & security –Update rate, continuity, etc.

4 Summary of architecture alternatives TechniqueCharacteristicTx for horiz. Position Add’l Req. Two way, aircraft basedDME DME-P/enhanced DME 2222 One way, aircraft basedPseudolite/heartbeat, DME/TDOA (DME-Loran) 3333 Gnd clock sync Hybrid, aircraft basedPseudolite/heartbeat, DME/TDOA (DME-Loran) 2222 Gnd clock sync Two way, ground basedActive MLAT (reverse DME)2 One way, ground basedPassive MLAT (reverse heartbeat) 3Gnd clock sync Hybrid, ground basedActive/Passive MLAT2Gnd clock sync

5 What can we simplify and why: Example Time removed from solution Time part of solution Ground Based DME DME-P DME heartbeat (with 2 way time) Pseudolite DME heartbeat Aircraft Based Active MLATPassive MLAT Each column should have similar coverage (geometry) Similarities due to geometry, number of measurements needed for solution –Assuming same ground stations used Difference due to error on each measurement, measurement time difference (if TDMA) –Accuracy will differ Implementation may differ greatly even though concepts similar

6 Test Scenario Matrix Performance in US (highlighting ~ busiest airports) Altitude: 350 ft AGL (RNP 0.3) and at altitude Ground infrastructure –1. DME stations –2. MLAT stations –3. Both –1-3 plus a few additions, depending on results above Solve for horizontal position with passive or active (& hybrid) concepts –Passive needs 3 stations (need to resolve user clock error) –Active needs 2 stations (assuming ambiguity can be resolved) Accuracy: start by calculating DOP –Gets a rough idea of required performance of ground infrastructure –Doesn’t cover all cases (i.e. range dependent accuracy, different accuracy between GBT, DME) RAIM/Integrity: Calculate residual matrix –Proposal: Ben and I will work on a reasonable quantity

7 Simplified Test Matrix Infrastructure/ accuracy DME OnlyMLAT OnlyDME & MLAT DOP (for 2 D, no clock sync) Coverage RNP 0.3, altitude DOP (for 2 D, clock sync) Test matrix for either passive or active/hybrid Full matrix in example represents 12 different tests –Can reduce number of cases –May not need to consider coverage at 350 ft for some cases Not necessarily final design – gets us some idea of performance –DOP is not adequate if accuracy vary (due to distance, GBT may differ from DME)

8 Accuracy Parameterized by ranging accuracy Ranging accuracy determined by –Equipment performance –Concept of operations (CONOPS) Ex. Simultaneous or serial measurements –Range dependent errors (propagation, SNR) –Rough approximation for σ= σ(d), or different σ for different ground transmitters Similar idea for RAIM integrity –Use nominal accuracy and minimum detectable error

9 DME Accuracy DME/N –System accuracy of 0.17 NM (up to 200 NM range) (ICAO Annex 10, as referenced by ION paper) –σ air = MAX(0.085 nm,.00125*d), σ sis = 0.05 nm, (AC90-100A) DME/P accuracy changes with distance from runway –15 m to 250 m (centerline) (position domain) (ICAO Annex 10)

MITRE Coverage tool for DME/GBT Rick Niles will discuss 10