Accession Number : ADA119367

Title :   L-Band DME Multipath Environment in the Microwave Landing System (MLS) Approach and Landing Region.

Descriptive Note : Project rept.,

Corporate Author : MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB

Personal Author(s) : Evans,James E

PDF Url : ADA119367

Report Date : 13 Apr 1982

Pagination or Media Count : 265

Abstract : The multipath environment in the approach and landing region represents an important factor in the optimization and ultimate performance of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P). Various types of multipath are assessed in the context of the proposed DME/P implementation error characteristics to ascertain the principal challenges. It is shown (analytically and experimentally) that specular reflections from buildings represent a significant challenge, particularly at low altitudes (e.g., category II decision height and below) where terrain lobing can cause the effective multipath levels to exceed the effective direct signal level. However, the time delay discrimination capabilities of the proposed DME/P should effectively eliminate the bulk of such multipath. Limited S-band (3 GHz) measurements of diffuse reflections from nominally flat terrain indicated very low levels. However, specular reflections from bare, hilly terrain may present problems in some cases. (Author)

Descriptors :   *Microwave landing systems, *Air traffic control systems, L band, Approach, Multipath radar, Distance measuring equipment, Terrain, S band, Multipath transmission, Aircraft landings, Runways, Specular reflection, Precision

Subject Categories : Flight Control and Instrumentation
      Terminal Flight Facilities
      Air Navigation and Guidance

Distribution Statement : APPROVED FOR PUBLIC RELEASE