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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>S-BAND RADAR PULSE DENSITIES IN THE LOS ANGELES AREA</title>
      <link>https://trid.trb.org/View/177339</link>
      <description><![CDATA[This report contains results of spectrum occupancy measurements made of the 2700-3100 MHz radar bands in the Los Angeles, CA, area. Approximately 500 sets of measurements were made, which included peak pulse amplitude, as well as the number of pulse counts at three threshold levels measured in 1 MHz frequency increments. These measurements have been combined and are displayed in this report in graphs showing the maximum, average, and minimum amplitude and pulse counts in 1 MHz frequency increments (400 samples). These measurements were made for the Federal Aviation Administration (FAA) by the Institute for Telecommunication Sciences (ITS) using the Radio Spectrum Measurement System, a computer-controlled spectrum analyzer system. The measurements will be used to quantify the S-band electromagnetic environment expected to be encountered with NEXRAD, a doppler weather radar currently under development. (Author)]]></description>
      <pubDate>Sat, 30 Aug 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/177339</guid>
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    <item>
      <title>ELECTROMAGNETIC COMPATIBILITY MEASUREMENTS AND ANALYSIS OF SYSTEMS IN THE 1535-1660 MHZ BAND</title>
      <link>https://trid.trb.org/View/41494</link>
      <description><![CDATA[Laboratory measurements were performed on a number of systems operating in the 1535-1660 MHz band to determine electromagnetic compatibility. These systems included: five types of radar altimeters operating in the 1600-1660 MHz band, three proposed air-to-air Collision Avoidance Systems (CAS) operating in the 1592.5-1622.5 MHz band, and a simulated Satellite Communication System operating in the 1622.5-1660 MHz uplink band and 1535-1578.5 MHz downlink band. The measurements revealed a distinct incompatibility between the three proposed CAS's and the APN-155, APN-159 and Bonzer TRN-70 radar altimeters; therefore, further analysis was performed to determine the effects of altimeter interference to CAS in an operational environment. (Author)]]></description>
      <pubDate>Sun, 13 Jul 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/41494</guid>
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      <title>L-BAND DME MULTIPATH ENVIRONMENT IN THE MICROWAVE LANDING SYSTEM (MLS) APPROACH AND LANDING REGION</title>
      <link>https://trid.trb.org/View/177599</link>
      <description><![CDATA[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)]]></description>
      <pubDate>Sat, 30 Nov 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/177599</guid>
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      <title>ZOOM ANTENNA</title>
      <link>https://trid.trb.org/View/177364</link>
      <description><![CDATA[In current ATC radars, high altitude targets are at a disadvantage when competing with low altitude undesired returns such as ground clutter ad birds. The zoom antenna technique is proposed as a means of virtually eliminating this problem. An implementation based on control of multiple elevation beams during each range sweep interval is recommended as applicable to both S-band and L-band ATC radars. (Author)]]></description>
      <pubDate>Fri, 30 Aug 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/177364</guid>
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    <item>
      <title>COAXIAL MAGNETRON SPECTRA AND INSTABILITIES</title>
      <link>https://trid.trb.org/View/57677</link>
      <description><![CDATA[Application of advanced radar clutter rejection techniques to FAA airport surveillance and enroute radars is constrained by inherent instabilities and spectral properties of the device used in the radar transmitter to generate high level RF pulse energy, and the degree to which its spectrum can be influenced by the circuit in which it operates. Coaxial magnetrons are believed to be spectrally pure, controllable and stable, and to embody other characteristics such as long life, which make them attractive replacements for the magnetrons presently employed. This report summarizes the results of extensive measurements made on a conventional S-band magnetron (presently employed in the ASR-7 radar) and a coaxial magnetron of equivalent pulse and power rating to compare their instabilities and spectral properties. (Author)]]></description>
      <pubDate>Wed, 30 Jan 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/57677</guid>
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    <item>
      <title>NEXT GENERATION AIRPORT SURVEILLANCE RADAR (ASR-( )) DEFINITION STUDY</title>
      <link>https://trid.trb.org/View/143781</link>
      <description><![CDATA[A study group was convened in the Summer of 1974 by the Federal Aviation Administration (FAA) to define the characteristics of the next generation airport surveillance radar (ASR). This was designated as the ASR-( ). The study group was comprised of representatives from MIT Lincoln Laboratory, the Johns Hopkins University Applied Physics Laboratory, MITRE, NAFEC, AAF, AAT, ASP, AEM and ARD. The operational requirements developed for the ASR-( ) include coverage on a small aircraft (one square meter radar cross section) out to 40 nautical miles; up to 15,000 feet altitude; at elevation angles of 0.3 to 30 degrees; in an environment of precipitation clutter, ground clutter, angel clutter, and anomalous propagation; and with a resolution commensurate with a separation standard of 2 nautical miles at a range of 30 nautical miles. Reliability, maintainability, and availability should be equal to that of the ASR-7 and ASR-8. Using the operational requirements, candidate radar systems were defined at four frequencies; VHF (420-450 MHz), L-band (1250-1350 MHz), and S-band (2700-2900 MHz) and 5'-band (3500-3700 MHz). The recommended system is the L-band system which has the following characteristics: azimuth beamwdith of 2.25 degrees, PRF of 1100-1360 pps, data rate of 4 sec., instrumented range of 60 nmi and a pulse width of 1.0 usec. (Author)]]></description>
      <pubDate>Mon, 11 Feb 1980 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/143781</guid>
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    <item>
      <title>TERMINAL RADAR INTERFERENCE CRITERIA STUDY</title>
      <link>https://trid.trb.org/View/75601</link>
      <description><![CDATA[Tests were undertaken to investigate the relationship between pulsed-type interference and the air traffic controller working in the terminal area. This was done by recording a series of pulsed-type interference cases and combining them with simulated analog radar targets to form a set of scenarios for display to a group of Federal Aviation Administration (FAA) controllers. Several operational responses were used as performance measures to investigate interference criteria. The interference cases were then quantified and ordered based on two indexing schemes. Tests based on the indices and the performance measures revealed that correlations exist between the operational responses and the interference cases. (Author)]]></description>
      <pubDate>Wed, 31 Oct 1979 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/75601</guid>
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    <item>
      <title>SHORT RANGE TERMINAL RADAR (SRTR) DEFINITION STUDY</title>
      <link>https://trid.trb.org/View/82472</link>
      <description><![CDATA[A Study group was convened in the Summer of 1974 by the FAA to define a Short Range Terminal Radar (SRTR) to be used at high traffic density VFR airports which do not presently qualify for an ASR. The study group was comprised of representatives from the Johns Hopkins University Applied Physics Laboratory, Lincoln Laboratory, MITRE, NAFEC, AAF, AAT, ASP, AEM and ARD. The operational requirements developed for the SRTR include coverage on a small aircraft (one square meter radar cross section) out to 16 nautical miles; up to 10,000 feet altitude; and in an environment of precipitation clutter, ground clutter, angel clutter, and anomalous propagation. The MTBF goal is 500 hours and the MTTR goal is one hour. Using these operational requirements candidate radar systems were defined at three frequencies, L-band (1250 - 1350 MHz), S-band (2700 - 2900 MHz) and S'-band (3500 - 3700) MHz). The recommended SRTR system is the S'-band system (3500 - 2700 MHz) and has the following characteristics: azimuth beamwidth of 3.4 deg, pulse width of 2 usecs, PRF of 2000 pps (average), instrumented range of 32 nautical miles, and a data rate of 4 sec. The establishment cost (in 1974 dollars) for this system is $324,000. (Author)]]></description>
      <pubDate>Wed, 14 Mar 1979 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/82472</guid>
    </item>
    <item>
      <title>THE LOGAN MLS MULTIPATH EXPERIMENT</title>
      <link>https://trid.trb.org/View/30016</link>
      <description><![CDATA[The National Plan for a Microwave Landing System (MLS) has specified a carrier frequency for the system in the vicinity of 5.1 GHz. At that frequency, no multipath data taken at a major civilian airport existed. The purpose of this experiment was to obtain such data at Logan International Airport in order to ascertain: (1) which objects are the major causes of measurable multipath reflections and their levels relative to the direct signal (M/D level), (2) whether or not the reflections from these objects can be satisfactorily simulated by the Lincoln computer model and, if so, how complicated must that model be, and (3) if the characteristics of multipath provide a significant discriminant between the Doppler and scanning beam techniques. It was found in the experiment that regions where reflections were noted could be predicted from ray optics and diffraction. No measurable reflections were noted elsewhere. For the purpose of modeling for multipath, building surfaces could be characterized as a flat plate with a reflection coefficient determined by measurement if it were a complicated surface, or by the dielectric properties of the surface material, if a simple surface. The airplane reflection model was also found to agree well with measurements. (Author)]]></description>
      <pubDate>Wed, 29 Dec 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/30016</guid>
    </item>
    <item>
      <title>NEW TECHNIQUES APPLIED TO AIR-TRAFFIC CONTROL RADARS</title>
      <link>https://trid.trb.org/View/138739</link>
      <description><![CDATA[The handling of extraneous reflections (clutter) is critical to radar performance. Some specific solutions incorporated in air traffic control radar systems are the use of linear large dynamic range, near-optimum digital signal processor, the use of electronically step-scanned antennas; the use of multiple PRF'S instead of staggered PRF's together with coherent transmitters to keep second- time-around clutter returns well correlated; the use of a fine grained ground clutter map to give superclutter visibility on tangential targets; and the use of lower operating frequencies to greatly reduce weather and angel returns. Two demonstration radar systems have been implemented, an S-band radar using a mechanically rotating antenna and a UHF radar using an electronically step-scanned cylindrical antenna. Experimental results are described.]]></description>
      <pubDate>Tue, 12 Nov 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/138739</guid>
    </item>
    <item>
      <title>ATC SURVEILLANCE/COMMUNICATION ANALYSIS AND PLANNING</title>
      <link>https://trid.trb.org/View/16221</link>
      <description><![CDATA[Under Task B, ASR Improvement Program, excellent results were obtained in detecting aircraft embedded in heavy clutter using a coherent S-band radar (klystron-equipped FPS-18) coupled to a specially programmed, wide dynamic range, digital signal processor. Initial results were obtained over a small area of the radar's coverage. Construction of a full coverage Moving Target Detector (MTD) with similar properties is nearing completion. Progress under Task D, which provides support to NAFEC programs airborne beacon interference locator (ABIL), transponder performance analyzer (TPA), and E-Scan, is continuing. Software development of ABIL airborne processing is nearing completion. TPA applications are being defined and experimental data reviewed. Detailed recommendations for E-Scan test goals and procedures have been prepared for antenna pattern measurements. Considerable progress under Task E, Precision Altitude and Landing Monitor (PALM), was made during this quarter. The antenna system is being fabricated, and delivery is expected shortly. All other principal components have been received and perform within limits. (Modified author abstract)]]></description>
      <pubDate>Tue, 18 Jun 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/16221</guid>
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