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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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      <title>AIRPORT SURFACE DETECTION EQUIPMENT (ASDE)-3 OPERATIONAL EVALUATION</title>
      <link>https://trid.trb.org/View/169224</link>
      <description><![CDATA[Operational tests were performed on the Airport Surface Detection Equipment (ASDE)-3 radar. Three teams of air traffic controllers, two per team, with current field ASDE-2 experience, were used as test subjects. The controllers were from the Eastern and New England Regions. These tests were conducted to determine the extent to which the ASDE-3 met requirements as presented by the Air Traffic Service and what the controllers' opinions were of the radar. Tests conducted were: airport surface coverage, capability, target detection as a function of speed between aircraft and aircraft to obstruction resolution, target size and shape determination, standing target heading, and runway clearance. (Author)]]></description>
      <pubDate>Fri, 15 Aug 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/169224</guid>
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    <item>
      <title>FLIGHT TESTS OF DIGITAL DATA TRANSMISSION AT VHF</title>
      <link>https://trid.trb.org/View/41495</link>
      <description><![CDATA[This report describes the results of a series of 11 experimental flights which measured the characteristics of air-to-ground digital transmission in the VHF aeronautical mobile frequency band. The tests were conducted for the Federal Aviation Administration at National Aviation Facilities Experimental Center in Atlantic City, NJ. Digital transmission rates of 2400 and 4800 bps were used with minimum-shift-keying (MSK) as the baseband modulation format. The MSK signal was transmitted on a test frequency of 120.85 MHz using conventional, air/ground voice communication equipment. A number of parameters were measured during the flights and an extensive decription is given of the bit error rates which were encountered. Received signal level was also monitored, and data describing average signal level and signal fading are presented. Other parameters measured were clock slips, carrier lossess, distribution of errors, and signal fading caused by aircraft maneuvering. The tests show that digital transmission rates of 2400 and 4800 bps can be supported, with existing FAA and ARINC equipment, at an average bit error rate near 0.00005. (Author)]]></description>
      <pubDate>Sun, 13 Jul 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/41495</guid>
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      <title>RADAR BEACON TRANSPONDER (RBX) FUNCTIONAL DESCRIPTION</title>
      <link>https://trid.trb.org/View/170419</link>
      <description><![CDATA[The Radar Beacon Transponder (RBX) is a ground-based transponder used to control the threat detection sensitivity level of BCAS aircraft operating in high density terminal airspace. The RBX is also used to deliver displayed resolution advisories from BCAS to the ATC facility. The normal DABS interrogation waveforms and message formats are used for communication between the RBX and BCAS aircraft. The appropriate BCAS sensitivity level is selected by comparing the BCAS aircraft position with an internally stored sensitivity level map of the surrounding airspace volume. This document provides a functional description of the RBX and shows that reliable performance is achievable in the presence ofinterference from ATCRBS and BCAS air-to-air interrogations. (Author)]]></description>
      <pubDate>Mon, 28 Oct 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/170419</guid>
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      <title>RADAR BEACON TRANSPONDER (RBX) INSTALLATION AND SITING CRITERIA</title>
      <link>https://trid.trb.org/View/170420</link>
      <description><![CDATA[The Radar Beacon Transponder (RBX) is a ground-based facility used in conjunction with other elements of the Active Beacon Collision Avoidance System (BCAS) to control the threat detection sensitivity level of BCAS aircraft and to convey displayed Resolution Advisories from the BCAS aircraft to the local ATC terminal facility. This paper describes the mechanisms of specular multipath reflection and signal shadowing, and discusses their impact on the RBX link power budget. Criteria for choice of RBX antenna height and location are presented. (Author)]]></description>
      <pubDate>Mon, 28 Oct 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/170420</guid>
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      <title>ACTIVE BCAS: DESIGN AND VALIDATION OF THE SURVEILLANCE SUBSYSTEM</title>
      <link>https://trid.trb.org/View/162834</link>
      <description><![CDATA[Lincoln Laboratory, under FAA sponsorship, is developing an Active Beacon Collision Avoidance System (BCAS), concentrating primarily on the air-to-air surveillance subsystem. The surveillance functions required are to detect the presence of nearby aircraft (whether they are equipped with ATCRBS transponders or DABS transponders), and then generate a surveillance track on each aircraft, issuing range and altitude reports once per second. The development effort consisted of airborne measurements complemented by simulation studies and analyses. The basic effects of ground-bounce multipath, interference, and power fading were assessed by air-to-air measurements. In other measurements, the BCAS interrogation and reply signal formats were transmitted between aircraft, and the results recorded for later playback and computer processing using the BCAS surveillance algorithms. This is a flexible means of experimentation which allows many of the design parameters to be changed as the effects are noted. In the most recent phase of the program, Lincoln designed and built realtime BCAS Experimental Units (BEUs), flight tested them, and then delivered them to the FAA for more extensive flight testing. In one of these flight tests, a BEU-equipped Boeing 727 flew to New York, Atlanta, and other major terminal areas in the eastern U.S. An analysis of BEU performance during this 'Eastern Tour' is given in this report. (Author)]]></description>
      <pubDate>Tue, 21 May 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/162834</guid>
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    <item>
      <title>DABS LINK PERFORMANCE CONSIDERATIONS</title>
      <link>https://trid.trb.org/View/24082</link>
      <description><![CDATA[The DABS link performance is computed using the present values for the system operating parameters and the available models that describe environmental and aircraft antenna effects. The various fade mechanisms are described, and a statistical determination of performance if proposed. The performance is computed for various sets of conditions including different ground antennas, aircraft maneuvers, antenna pedestal heights, ground reflection coefficients and reduced power. Also discussed are the effects of obstructions and the performance when aircraft are in the cone of silence. The DABS link is found to have very good overall performance with only small regions of reduced reliability that are at low angles or due to maneuvers. Those missed replies due to maneuvers are found to be sporadic from scan to scan.]]></description>
      <pubDate>Thu, 26 Jun 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/24082</guid>
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      <title>MULTIPATH IN AIR TRAFFIC CONTROL FREQUENCY BANDS. VOLUME I. CLASSIFICATION OF MULTIPATH, EFFECTS OF MULTIPATH ON SYSTEMS, AND CAUSES OF MULTIPATH</title>
      <link>https://trid.trb.org/View/23600</link>
      <description><![CDATA[The handbook has collected theories and techniques which have one or more of the following qualities: It has been in frequent use by engineers; it has been shown to be accurate; it can be applied to a wide variety of problems; it offers an easily obtainable upper or lower bound. Most of the problems arising because of multipath cannot be solved or described precisely, but instead involve assumptions or approximations, the effects of which cannot be quantified. The responsibility for the decision on which approximation or assumption to use for a particular problem is with the reader. Since the handbook is directed toward air traffic control (ATC) frequencies, most of the material presented is oriented toward frequencies above VHF, and toward line-of-sight paths. Two special sections, one on Omega and one on Loran are included. No information on HF propagation or ionospheric scatter is included. Finally, selection of the material in this handbook has been heavily influenced by the systems presently used by the FAA.]]></description>
      <pubDate>Tue, 22 Apr 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/23600</guid>
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    <item>
      <title>MULTIPATH IN AIR TRAFFIC CONTROL FREQUENCY BANDS. VOLUME II. CHAPTERS CIII THROUGH GIV, GENERAL BIBLIOGRAPHY</title>
      <link>https://trid.trb.org/View/23601</link>
      <description><![CDATA[The refractive index in the troposphere between 100 MHz and 100 GHz; Tropospheric multipath mechanisms; Other atmospheric effects; Techniques for computing refraction of radio waves in the troposphere; Global scintillation model; Molecular transfer characteristics of air between 40 and 140 GHz; Doppler effects; Methods for reducing the effects of multipath; Multipath calculations for a VOR site; Multipath effects at low frequencies with particular reference to the Loran-C Radio Navigation System; Multipath for the Omega System; Multipath problem for beacon radar.]]></description>
      <pubDate>Tue, 22 Apr 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/23601</guid>
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