MLS Multipath Studies, Phase 3, Final Report, Volume III .
FAA-RD-79-21Project ReportATC-88Volume III, 2MLS Multipath Studies, Phase 3 Final ReportVolume III: Application of Models to MLSAssessment IssuesPart 2J. E. EvansS. J. DolinarD. A. Shnidman8 June 1981Lincoln LaboratoryMASSACHUSETTS INSTITUTE OF TECHNOLOGYLEXINGTON, MASSACHUSETTSPrepared for the Federal Aviation Administration,Washington, D.C. 20591This document is available to the public throughthe National Technical Information Service,Springfield, VA 22161
This document is disseminated under the sponsorship of the Departmentof Transportation in the interest of information exchange. The UnitedStates Government assumes no liability for its contents or use thereof.
Technical Report Documentation Page2.1. Report No.3.Government Accession No.RecipIent's Catalog No.FAA-RD-79-214. Title and Subtitle5. Report Dote8 June 1981MLS Multipath Studies, Phase 3. Final Report, Volume Ill:Application of Models to MLS Assessment Issues6. Performing Orgoni lotion Code7. Author! s)8.9.10. Work Unit No. (TRAIS)Performing Organization Nome and AddressMassachusetts Institute of TechnologyLincoln LaboratoryP.O. Box 73Lexington, MA 0217312.15.!11.Contract or Grant No.13.Type of Report and Period CoveredDOT-FA74-WAl-461Sponsoring Agency Nome and AddressProject ReportDepartment of TransportationFederal Aviation AdministrationSystem Research and Development ServiceWashington, DC 20591IPerforming Orgoni zation Report No.ATC-88, Volume Ill, Part IIJames E. Evans, Samuel J. Dolinar, and David A. Shnidman14.Sponsoring Agency CodeSupplementary NotesThe work reported in this document was performed at Lincoln Laboratory, a center for research operated byMassachusetts Institute of Technology under Air Force Contract FI9628-80-C-0002.16. AbstractThis report presents work done during phase 3 of the US national Microwave Landing System (MLS) programtoward developing a computer simulation model of MLS multipath effects, the experimental validation of the model,and the application of the model to investigate multipath performance of ICAO proposals for the new approach andlanding guidance system.The first two volumes of the report presented an overview of the simulation effort as well as describing in detail the propagation and MLS technique mathematical models and their validation by comparison with experimentaldata. In this volume, we describe the results of comparative simulations for the various MLS techniques in variousscenarios and analyze in detail certain multipath performance features which were found to be significant in thescenario simulations.Simulation results are presented for several scenarios, and shadoWing of the MLS azimuth by taxiing and overflying aircraft is analyzed.The remainder of the report focuses on multipath performance factors specific to various individual techniques.These include: ( I) the effects of angle data outlier tests and filtering in the TRSB receivers,(2) the effects on the DMLS system due to receiver AGe, receiver motion-induced Doppler shifts, and the useof commutated reference systems, and(3) acquisition/validation algorithms for all three techniques.The report concludes with a summary and suggestions for future work.Part I of this volume consists of Chapters I through IV; Part II contains Chapters V through VlII and the Appendices.18.17. Key Word.Microwave Landing System (MLS)MultipathDoppler MLS (DMLS)Time Reference Scanning Beam (TRSB)DME Based Landing System (DLS)19. Securi ty C105.i f. (of thi 5 r.port)Document is available to the public throughthe National Technical Information Service,Springfield, VA 22151.20. Securi ty Cloui!. (ol thi. pog.)(8-72)Reproduction of completed page21. No. 01 Pog .320UnclassifiedUnclassifiedForm DOT F UOO.7Distribution Statementauthori ed22. Price
ABSTRACT.This report presents work done during phase 3 of the US National MicrowaveLanding System (MLS) program toward developing a computer simulation model ofi'llJS multipath effects, the experimental validation of the model, and theapplication of the model to investigate the multipath performance of proposalsfor the new approach and landing guidance system. The model was developed byseparately considering the charactertistics of the four basic elements affecting system operation in a multipath environment, i.e., airport, flight prof Ue, propagation, and system elements.This modeling approach permits theexaminatlon of the effect on system performance of individual multipath performance factors such as:(a) reflections from terrain, aircraft, buildingswith differing orientations; (b) shadowing by aircraft, buildings, and convexrunways; (c) aircraft flight profiles and approach speeds; and (d) systemdesign features to combat multipath.The first two volumes of the report presented an overview of the simulation effort as well as describing in detail the propagation and MLS techniquemathematical models and their validation by compaLison with experimentaldata.In this volwne, we describe the results of comparative simulations fortile various HLS techniques in various scenarios and analyze in detail certainmultipath performance features which were found to be significant in thescenario simulations.Simulation results are presented both for the common comparative scenarios developed by the AWOP Working Group A (WG-A) multipath subgroup and foradditional scenarios suggested by individual members of WG-A.Shadowing ofthe MLS azimuth by taxiing and overflying aircraft is analyzed analytically.by comparison of various field results and by comparative simulations.The remainder of -the report focuses on multipath performance factorsspecific to various individual techniques. These include:(1)the effects of angle data outlier tests and filtering inthe TRSB receivers(2)the effects on the OMLS system due to the receiver AGC,receiver motion-induced .Doppler shifts, and the use ofcommutated reference systems, llthreetech-The report concludes 'lith a summary and suggestions for future work.Part I of this volume consists of Chapters I through IV; Part II containsChapters V through VIII and the appendices.iii
ACt .NmlLEDGHENTSThe theoretical, simulation result, and field data analyses in this volume11ad significant contributions from several people in addition to the reportauthors.R. Orr contributed to the AWOP scenario result analysis as well asthe TKStl shadowing and slew limiter studies.D. Shnidman analyzed the AWOPscenario multipath features and features of the DLS system performance. SteveSussman contributed to the analysis of Doppler reference scalloping effects.Hob Burchsted, Janet Reid, and Bob Moffatt assisted in running many of thescenarios.The studies on DMLS reference scalloping benefited from work byH. Wheeler of Hazeltine Corporation [11], J. Goodwin of ITT Gilfillan [13],and 1. White of Plessey Company [140J.D. Vickers, G. Adams, J. Tracy, andlL Cleary of the Federal Aviation Administration provided the experimentaldata used in the shadowing studies (this included conducting a series ofspecial field tests to address certain issues). Tne AWOP WG-A multipatn subgroup chaired by R. Butler was instrwnental inthe development and use of the comparative multipath scenarios. Other principal contributors from the subgroup included N. Hughes, J. Jones, H. Ecklundt,T. Hagenberg, and D. Cooper.Tne encouragement of H. Weiss and I. Stiglitz of Lincoln Laboratory andF. Frisbie of the Federal Aviation Administration for our various studies whenconsiderable controversy arose is gratefully acknowledged.D. Young and N. Campbell typed theS. Cormney prepared the bulk of the figures.report,whileC.Casazzaand ,.iv
CONTENTSiiiivviiAbstractAcknowledgmentsList of Illustrations V.1VI.fIVII. VIII.EFFECTS OF SLEW RATE LIMITING IN TRSB RECEIVERSA. IntroductionB. TRSB Phase II Data ProcessingC. Single Scan Multipath Error for a TRSBDwell Gate ProcessorD. Phase II Slew Limiter PhenomenologyE. Slew Rate Limiter at Filter OutputF. Conclusions/ExtensionsUNIQUE DMLS MULTIPATH PERFORMANCE ISSUESA. Effect of Time-Varying AGC Gain on the EffectiveDMLS Antenna PatternsB. Reference ScallopingC. Array ScallopingD. Lateral DiversityE. Comparative Simulations of Scenarios Relatedto DMLS Multipath MechanismsF. Potential Impact of Various DMLS DynamicFactors on System ImplementationACQUISITION/VALIDATION (ACQ/VAL) STUDIESA. TRSB ACQ/VALB. DLS ACQ/VALC. Doppler ACQ/VALD. TRSB/DMLS Comparative Simulation ResultsE. SummarySUMMARY AND RECOMMENDATIONS FOR FUTURE STUDIESA. Summary of ResultsB. Recommendations for Future 6-1186-1547-17-37-57-87-387-538-18-18-5
APPENDIX A Comparison of "Standard" and "Special" DMLSSimulation Models for a Spatially HomogeneousBuildingA-lAPPENDIX B System Implementations SimulatedB-1APPENDIX C Simultaneous Corrmutation in DMLS ArraysC-lReferencesR- 1 , vi
LIST OF ILLUSTRATIONS 5-1Data editing structure employing slew ratelimiters.5-Z5-2Input-output characteristic for slew limiter.5-85-3Input-output time waveforms with TRSB Phase IIreceiver slew limiter.5-85-4Illustration of determining P , P and long duration multipath error with slew limiter 5-145-5Slew bias error vs. separation angle for variousmultipath amplitudes.5-165-6Slew bias error vs. multipath amplitude for variousseparation angles.5-175-7Slew limiting at filter output or input.5-205-8Input and output waveforms for case of limiteroutside feedback loop.5-265-9Maximum outlier amplitude for a given maximumoutput error.5-286-1Sum filter frequency response for zero scallopingfrequency (uniform AGC factors).6-46-ZDifference filter frequency response for zeroscalloping frequency (uniform AGC factors).6-66-3Sum filter frrquzncy response for scalloping6-1Zfrequency of 2 16; (210 Hz) and midscan phase of 0 .6-4Difference fitte frequency response for scalloping 6-13frequency of I 16; (210 Hz) and midscan phase of 0 .6-5aReal part of sum ilterscalloping frequency ofphase of 90 .tfre2 encyresponse for16T (210 Hz) and midscan6-146-5bImaginary part of sum fitte2 frequency resonse forscalloping frequency of I 16; (Z10 Hz) and midscanphase of 90 .6-156-6aReal part of difference filtrrzfrequency responsefor scallopi g :requency of I l;T (210 Hz) and midscan phase of 0 6-166-6bImaginary part of difference filter ffeq encyresponse for scalloping frequency of 2 16; (210 Hz)and midscan phase of 90 .6-172vii
6-7Sum filter1fr2 uency response for scalloping frequency of 216T (210 Hz) and midscan phase of 180 .6-186-8Difference filte1 frequency response for scallopingfrequency of 2 16; (210 Hz) and mid scan phase of180 .6-196-9Sum filter frequency response for scalloping fre2quency of l T (420 Hz) and midscan phase of 0 .6-206-10Difference fi ter frequency response for scallopingfrequency of l T (420 Hz) and mid scan phase of 0 .6-216-11aReal part of sum filter f e quency response for1scalloping frequency of 16; (420 Hz) and midscan phase of 90 .6-226-11bImaginary part of sum filZeL frequency response forscalloping frequency of 16; (420 Hz) and mid scanphase of 90 .6-236-12aReal part of difference filte frequency response2for scalloping frequency of 16; (420 Hz) andmidscan phase of 90 .6-246-12bImaginary part of difference frequency response2for scalloping frequency of l T (420 Hz) andmid scan phase of 90 .6-256-13Sum filter frequency response for scalloping fre2quencyof l T (420 Hz) and midscan phase of 180 .6-266-14Difference fitter frequency response for scalloping 6-27frequency of l T (420 Hz) and midscan phase of 180 .6-15Motion averaging factor for proposed scan sequencedp(n) (111111 -----).6-446-16Motion averaging factor for alternating scansequence dA(n) ( - - - - - -).6-466-17Motion averaging factor for scan sequence #8196-54( -- --t -- ) .6-18Motion averaging factor for scan sequence #2376-55( --- -- -) .6-19Motion averaging factor for scan sequence #3476-56( - - -- --) .6-20Motion averaging factor for scan sequence #700( - - ----t ) .v;;;6-57,
6-216-22First-order static error characteristic,pH (w ) Motion averaged errors for proposed scan sequenced (n)p(I I I I I I6-626-78---) 6-23Motion averaged errors for alternating scansequence dA(n) ( - - - - - -).6-806-24Motion averaged errors for scan sequence #8196-81( -- -- -- ) .t6-25Motion averaged errors for scan sequence #2376-82( --- -- -).6-26Motion averaged errors for scan sequence #3476-83( - - -- -- ) 6-27Motion averaged errors for scan sequence #7006-28aMotion averaging factor for proposed scan sequence6-88dp(n) (I I I I I I -----) with zero multipath time delay.6-28bMotion averaging factor for proposed scan sequencedp(n) (I I I I I I -----) with multipath time delay of6 ].lsec.6-906-29aMotion averaging factor for alternating scansequence dA(n) ( - - - - - ) with zero multipathtime delay.6-916-29bMotion averaging factor for alternating scansequence dA(n) ( - - - - - -) with multipathtime delay of 6 ].lsec.6-926-30Scalloping frequency geometry.6-946-31Dynamic DMLS "inbeam" multipath region for reflected 6-96array x direct reference component.6-32DMLS single frequency static error vs. separationangle.6-986-33DMLS dynamic error for out-of-beam azimuthmultipath.6-1006-34 and6-35Dynamic DMLS error vs. scalloping frequency forout-of-beam azimuth multipath.6-1026-36Simple lateral diversity sequence.6-1046-37Error components at Doppler angle decoder inputfor single multipath reflection.6-1056-84( - - ---- ) ix
6-38Lateral diversity elevation with reflectiveobject (from [7]).6-1066-39Final UK lateral diversity array concept proposal.6-1126-40Lateral diversity antenna used in initial trialsalongside phase 1 antenna.6-1136-41Experimental and simulation results for performance improvement with lateral diversity.6-1166-42Brussels Airport map.6-1206-43Airport map for "system sensitivity" scenarioderived from Fig. 6-42.6-1216-44Azimuth multipath characteristics for scenarioof Fig. 6-43.6-1226-45DMLS error for Brussels scenario with thresholdheight of 50 ft.6-1246-46Brussels National Airport.6-1266-47Brussels National landing chart ICAO.6-1286-48Abelag hangar as seen from fuel storage area.6-1296-49Map of Brussels airport fuel storage area.6-1306-50Aerial photograph of Brussels National Airport.6-1326-51Inferred fuel storage area structure locationsand heights.6-1346-52Vertical plan view of Abelag Hangar shadowingby fuel storage area structures.6-1356-53Inferred shadowing profile of fuel storage area.6-1366-54Airport map for comparative scenario based on June1977 Brussels airport environment.6-1406-55Azimuth multipath diagnostics for comparativescenario of Fig. 6-54.6-1416-56Computed raw errors for comparative scenario ofFig. 6-54.6-1426-57Door spacing of hangars for scenario based onSydney Airport.6-1446-58Airport map for "system sensitivity" scenarioderived from Sydney Airport.6-146x
.6-59Azimuth multipath diagnostics for scenario ofFig. 6-58.6-1486-60Azimuth error waveforms for "system sensitivity"scenario based on Sydney Airport.6-1496-61Airport map used to derive array scalloping "systemsensitivity" scenario.6-1506-62Airport map for array scalloping scenario.6-1526-63Azimuth multipath characteristics for arrayscalloping scenario.6-1526-64TRSH and DMLS azimuth multipath errors for arrayscalloping scenario.6-1537-1DLS time delay discrimination as a function ofscatterer location.7-67-2Summary of DMLS ACQ/VAL.7-107-3DMLS ACQ/VAL flow chart.7-117-4Acquisition/validation for correlation processor.7-127-5Frequency response characteristic of DMLSordinary" acquisition bins.7-147-6Output of DMLS pairwise "ordinary" bin summationsfor single input signal.7-167-7Airport map for original WP/322 ACQ/VAL scenario.7-407-8Azimuth multipath characteristics for originalWP/322 ACQ/VAL scenario.7-417-9DMLS and TRSB errors for original WP/322 ACQ/VALscenario.7-427-10Di1LS and TRSB errors for original WP/322 ACQ/VALscenario.7-447-11Long and short term tracked averages time historyfor original WP/322 ACQ/VAL scenario.7-467-12Azimuth multipath characteristics for WP/322scenario at 118 knots ground speed.7-477-13DMLS and TRSB errors for WP/322 scenario at118 knots ground speed.7-48,.xi
7-14Long and short term tracked averages time historyfor WP/322 scenario at 118 knots.7-507-15Azimuth multipath characteristics for WP/322ACQ/VAL scenario at 80 knots.7-517-16DMLS and TRSB errors for WP/322 ACQ/VAL scenarioat 80 knots.7-527-17Long and short term tracked averages time historyfor WP/322 scenario at 80 knots.7-54A-IAirport map for test scenario using "special" DMLSsimulation model.A-2A-2Azimuth multipath diagnostics for test scenariousing "special" DMLS model.A-3A-3Azimuth multipath diagnostics using "standard" DMLSsimulation model.A-4A-4Comparison of "standard" and "special" DMLS modelsfor test scenario.A-5B-1DLS azimuth antenna configuration.B-2B-2DLS lateral diversity EL antenna.B-3C-1One argument for increased Doppler resolutionvia "two source mobility".C-4C-2aCommutated Doppler array.C-6C-2bGround derived system which is dual tocommutated Doppler array.C-6C-3Simultaneous linear two source movement.C-8C-4Sequential linear two source movement.C-12C-5Spectra of various Doppler components.C-14C-6Time waveforms with sequential lineartwo source movement.C-16xii,
C-7Reference/sideband source locations in randomized two source movement.C-18C-8Relation of phase perturbations to sideband/reference separation.C-22C-9Relation of various phasors for "normal" commutated Doppler array at 0.5 BW separation angle.C-30C-IORelation of various phasors for simultaneoustwo source commutation at separation angle 0.5 bealllwidths C-32.xiii
V.EFFECTS OF SLEW RATE LIMITING IN TRSB RECEIVERSA.IntroductionThe MLS, as embodied in the various states' system proposals evaluated by 1ICAO,is an example of a class of systems which is commonly encountered inmany areas of communication and control, especially radio-navigation - multirate sampled data system.The multirate property is inherent. in the cap a-bility of the system to make raw measurements at a rate exceeding the user'srequirementsforoutput data.In this situation,it is customary to usetechniques of data processing/reduction to refine the raw estimates before thepresentation to the user.In particular, the excess data rate at the input permits incorporation ofdata editing procedures which can eliminate or otherwise preprocess individualdata points which seem to be highly at variance with the character of theadjacent data.rejection tests.programs,In certain statistical literature, these are known as outlierThese have had application within the several national MLSand it is within this general context that the specific problemstudied in this report is introduced.AFigure 5-1 shows an editing structure representative of those employed in,versions of the U.S. TRSB receiver.indicated.Possible options for feedback are alsoThe specific editor used is a slew rateli iter,which is a non-linear device that truncates a data point at some limiting value if the datadeviates sufficiently far from a predicted, or reference, level.In the PhaseII receiver, the limiter was placed ahead of the filter; no post-filter processing was performed.The rationale for the limiter-before-filter config-uration is primarily to prevent the propagation of anomalous values (resulting5-1
-RawMeasure mentsU1INSlew RateLimiterrTLinearFilter1.---,Fig. 5-1. -,,- . ----, Output to User.li.--.-.-.,-.---.-.-.------.- --1-.---.--Ii'"Slew RateLimi terData editing structure employing slew rate limiters .
from things such as momentary equipment failures or adjacent channel interference, e.g., C-band weather radar pulses) through the relatively narrow-bandfilter wherein their effects would persist for too long a time.Secondarily,it provides a measure of immunity to short duration, high intensity multipathperturbations ("bright flash").It is not difficult to design configurationswhich achieve reasonable succes
Assessment Issues Part 2 J. E. Evans S. J. Dolinar D. A. Shnidman 8 June 1981 Prepared for the Federal Aviation Administration, Washington, D.C. 20591 This document is available to the public through the National Technical Information Service, Springfield, VA 22161
Indiana AOR MLS Indiana Regional MLS MIBOR REALTOR . David Bennett –Pinellas REALTOR Organization dbennett@tampabayrealtor.com Kevin McQueen –T3 MLS (949) 771-0303 kevin@t3sixty.com. Title: AEI Embracing MLS Consolidation - Kevin McQueen v1 Author: Kevin McQueen - T3 MLS
Regional MLS Rules (Cont'd) (kk) "MLS Data Input Form" means the data input form, as prescribed by the Association from time to time to be used to obtain and submit property information for an MLS Listing. (ll) "MLS Listing" means a listing which is entered onto the MLS System database and includes: i) the Listing .
Inter-domain multipath routing in connection-oriented carrier-grade networks is a new topic and previous work has primarily addressed single domain scenarios. In our past work [8], we have explored the usage of multipath routing with multi-domain reach in carrier-grade Ethernet. In order to facilitate the inter-domain multipath routing, we proposed
design for overlapping multipath components and extend receiver design to realistic multipath channels with per-path distortion, with focus on complexity/performance tradeoffs for proposed templates. Propagation gain analysis for multipath channels and possible implications on adaptive transmission are discussed in section V. II.
434 Riverside Dr, Tarpon Springs, FL 34689-2512, Pinellas County MLS Beds 4 MLS Sq Ft 1,440 Lot Sq Ft 6,691 MLS List Price 139,900 MLS Baths 1 Yr Built 1929 Type SFR MLS List Date 11/12/2017 Active Listing Owner Information . Realtor Information List Agent: Fay Miller Patrick E-mail: daintia@verizon.net Agent ID: 261505276 Agent Fax: 813-231 .
from the Theogony (MLS 4), “The Ages of Man” from Works and Days (MLS 4) W 01/30 MLS 7: Poseidon and Sea Deities Review for Exam 1 F 02/01 Exam 1 Week Five: The Archetype of the Virgin Goddess; Hindu Mythology M 02/04 MLS 8: Athena W 02/06 MLS 10: Artemis
- To Disclose - (San Diego MLS syncs to CRMLS) - The following will not pull over to the CRMLS MLS from San Diego MLS system if you input the Residential listing yourself. - 1. San Diego MLS's system uses Neighborhoods and zip-codes, CRMLS Does not. CRMLS uses Area numbers, All Data Share listings from San Diego MLS show up
Total new MLS listings and total MLS sales for entire district. The Victoria Real Estate Board uses the MLS Home Price Index (MLS HPI) to report on market trends. The MLS HPI uses the concept of a benchmark home, a notional home with common attributes of typical homes in a defined area.
