Loran Integrity Performance Panel The Loran Integrity Performance Panel (LORIPP) The LORIPP Team Loran Team Meeting McLean, VA July 30, 2002

Loran Integrity Performance Panel LORIPP Background What is LORIPP and why does it exist? QDetermine Requirements (System Engineering) QIdentify Threats to Loran and Determine Threat Allocations (Fault Tree) QBound/Mitigate Effects of these Threats QDevelop Threat Models QProvide Substantiated Information on Loran Capabilities What will we accomplish? QProve Stand Alone Loran Can Act as a Redundant Navigation System (RNP 0.3 or 0.5)

Loran Integrity Performance Panel Threats to Loran Integrity Transmitter Propagation Effects QInterference (Atmospheric Noise, P Static, Sky Wave) QGround Wave Propagation Phenomena (ASF, ECD, SNR) Receiver

Loran Integrity Performance Panel LORIPP Work Plan Transmitter Performance (LSU, PIG, Tom G., NAVCEN) Receiver Algorithms & Performance (PIG, Stanford, USCGA) Fault Tree (Stanford, Kevin B., NAVCEN) System Engineering (PIG, Bob W.) P-Static Evaluation (Bob E., Bob T., Bob L., Bob W., Frank G., Kevin B.) Atmospheric Noise (Stanford, PIG, Kevin B., Bob W.) Ground Wave Propagation: ASF, ECD and Signal Strength (Bob W., USCGA, NAVCEN, LSU, PIG, Tom G., OU, FAATC) Loran Communications (Stanford, PIG, Frank G.) Sky Wave (Bob W., USCGA) Documentation & Meeting Logistics (Tom G., Stanford, NAVCEN)

Loran Integrity Performance Panel System Engineering Development of Coverage Analysis Tools Calculation of Continuity & 95% Accuracy Reliability, i.e., Mean Time between Failures, etc. QAvionics QNew Transmitter Equipment (validate assumptions)

Loran Integrity Performance Panel Fault Tree Integrity Fault Tree Continuity Fault Tree Determine Allocations in Error Budget Q ECD (propagation, receiver calibration, receiver noise) Q TOA (receiver noise) QTails of the distributions

Loran Integrity Performance Panel Preliminary Integrity Fault Tree Probability (HPE > HPL) > /hour Probability Transmitter Caused HMI Probability Propagation Caused HMI Probability Receiver Caused HMI Transmitter Timing Evil Waveform CW RFI Sky Wave ASF Effects Cross Rate ECD

Loran Integrity Performance Panel Transmitter Performance Determine ABS Threshold, Time to Blink from Onset of Fault, Probability of Out of Tolerance w/o blink Determine Transmitted ECD Tolerance, Blink on transmitted ECD? *** Determine Threat Monitor Requirements at transmitter, Certification Requirements for Monitors Calibration re UTC Chain Operations Q TOE verus SAM Analysis of coverage under each situation Q Control of TOE to UTC vs measurement of TOE to UTC and transmission of measured offset

Loran Integrity Performance Panel Receiver Algorithms & Performance (1/2) Determine the probability of false alarm & missed detection of blink/off air at given SNR (given time to alarm requirement) Establish SNR Threshold (for reliably identifying the correct station & cycle) with 7 9s of confidence Master independent, multi-chain navigation Q Resolution of 200 usec cross chain lane ambiguities Q Identification of secondary w/o master Loran Cycle Integrity Calculations Q Weighted Sum Squared Error vs Sum Squared Error Q Analysis of probability of cycle slips after verifying cycle integrity

Loran Integrity Performance Panel Receiver Algorithms & Performance (2/2) Input from Potential Manufacturers – Validate Assumptions of HMI Analysis Determine ECD Requirement Determine Loop Time Constants Develop Simulator Q Averaging time Q HPL calculation

Loran Integrity Performance Panel Basic Receiver HMI Algorithm Cycle Resolution Verifies that the correct cycle is being tracked Determine P wc (probability of being on the wrong cycle) HPL Calculation Determines the % confidence bound on horizontal error Determine HPL Cannot meet RNP 0.3 or 0.5 Requirements P wc < 1x10 -7 P wc > 1x10 -7 HPL > 0.3 NM (RNP 0.3) HPL > 0.5 NM (RNP 0.5) HPL < 0.3 NM HPL < 0.5 NM

Loran Integrity Performance Panel HPL Equation Uncorrelated Bias Terms Random Terms Correlated Bias Terms

Loran Integrity Performance Panel P Static Educate LORIPP via tutorial paper and briefing. Determine how P static fits into Fault Tree QDifferent faults caused by P static and Allocations What would the continuity allocation be? What is max level of P static Developing H-field Antenna Test Plan and, at a minimum, determine a figure for SNR drop outdoors

Loran Integrity Performance Panel Atmospheric Noise Determine the necessary analysis level, i.e., 95%, 99%, or 99.9%, worst time period or averaged over time? Determine and Develop Applicable Databases Time Domain Model for Simulation Determine the credit that can be claimed for non-linear processing Implement Results in Simulator and Receiver

Loran Integrity Performance Panel Ground Wave Propagation: ASF, ECD and Signal Strength Data Collection QGuidance/requirements definition for data collection effort (also collecting ECD & SNR data) QCoordinate with Atmospheric Noise Threat Model Data Analysis Q % bounds on remaining errors QCorrelated vs. Uncorrelated terms QMathematical modeling & prediction including terrain of SS, ECD, & ASF?

Loran Integrity Performance Panel Sky Wave Quantify effects on TOA bias Quantify effects on ECD bias Receiver technology for mitigation Integrity Allocation & Threat Model

Loran Integrity Performance Panel Loran Communications Effects on Navigation if Signals are Modulated Impact on Availability, Integrity, Accuracy, & Continuity if Loran Data is Transmitted QWhat data? QAnd at what rates? Quantify the benefits provided by the data channel in improving Loran Nav. performance (Availability, Integrity, Accuracy, & Continuity)

Loran Integrity Performance Panel Documentation & Meeting Logistics Collect White Papers from Briefings Loran/LORIPP Web resource? Meeting Minutes Organize Project and Arrange Priorities Determine Documentation Methodology

Loran Integrity Performance Panel Summary The LORIPP just had its first meeting this past week QThe major (critical) issues for Loran RNP 0.3 were discussed QA work plan was developed to gather the data and perform the analysis necessary to prove Loran performance QFuture meetings are planned to further develop the integrity analysis – late September