<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>FIXED SITE COMPARISON OF P AND C/A CODE RANGING PERFORMANCE USING GPS X-SETS</title>
      <link>https://trid.trb.org/View/177598</link>
      <description><![CDATA[The NAVSTAF Global Positioning System (GPS) is a satellite-based navigation system under development by the Department of Defense. Satellites transmit a precise (P) code and a clear/acquisition (C/A) code which are used to calculate satellite to user range. Ranges from three or more satellites are then used to determine the user's position. The Johns Hopkins University Applied Physics Laboratory (APL) has two identical receivers, each of which is capable of tracking either code. The purpose of the study was to examine the characteristics of the C/A code as it might be used by a marine user with a low-cost GPS receiver. The study found that the single-frequency P and C/A code range residuals and navigation errors show the same basic characteristics, except for expected higher noise levels in the C/A code, and possible multi-path interference in the C/A code of one satellite as it set. The dual-frequency P code phase delay measurements provided ionospheric corrections that appeared reasonable in character and value. The ionospheric contribution to position error was found to be largest when two or four satellites were at low elevation. At other times the ionospheric effect on position error appeared negligible.]]></description>
      <pubDate>Sun, 30 Nov 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/177598</guid>
    </item>
    <item>
      <title>APPLICATION OF SEMI-EMPIRICAL TD GRID CALIBRATION TO THE WEST COAST LORAN-C CHAIN</title>
      <link>https://trid.trb.org/View/171290</link>
      <description><![CDATA[This study demonstrates the utility of semi-empirical Loran-C time difference (TD) grid calibration techniques. Theory is employed to determine the functional dependence of TDs on range and bearing from the Loran-C chain stations. TD measurement data are then utilized to calibrate the unknown coefficients incorporated in the semi-empirical TD model. A semi-empirical model is presented for the West Coast Loran-C chain where at-sea TD measurement data in Southern California revealed large discrepancies between U.S. Coast Guard original predictions and measurements. A significant reduction in the TD errors is achieved with the semi-empirically-calibrated model relative to the U.S. Coast Guard original grid. The accuracy of the calibrated West Coast Loran-C grid is further evaluated by comparing the calibrated grid with measurements which are not used in model calibration. Results are also presented which show the sensitivity of the model accuracy to the quantity and distribution of measurement data used to calibrate the model. Guidelines are formulated to aid in the design of data collection requirements for future semi-empirical grid calibration efforts. (Author)]]></description>
      <pubDate>Wed, 29 Jan 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/171290</guid>
    </item>
    <item>
      <title>EXPERIMENTAL BCAS PERFORMANCE RESULTS</title>
      <link>https://trid.trb.org/View/77744</link>
      <description><![CDATA[The results of the (Litchford) Beacon-based Collision Avoidance System concept feasibility evaluation are reported. Included are a description of the concept, analysis and flight test results. The system concept is based on the range and bearing measurements for detecting and resolving a threat. The experimental hardware, developed under Contract No. DOT-TSC-1103, Task 1-8, did not implement the automatic radar selection and lock-on mode and the capability to compute target range and bearing in real time which the concept requires. These enhancements are currently being implemented. All three generic modes of the BCAS were evaluated. These are: the passive (listen-in), the active (interrogate by on-board transmitter), and the combined (active-passive). Also, reported are results are results of the comprehensive in-house study effort conducted on the azimuth signal requirements and on single-site feasibility. It is concluded that the BCAS is a technically feasible concept and that the passive mode with an azimuth reference signal would be more accurate and less troublesome than other BCAS alternatives. For each operating mode there are geometries in which system performance fails or is degraded to some degree. System reliability may therefore require the implementation of various operating modes. (Author)]]></description>
      <pubDate>Sun, 29 Dec 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/77744</guid>
    </item>
    <item>
      <title>LORAN-BASED BUOY POSITION AUDITING SYSTEMS. ANALYTICAL EVALUATION</title>
      <link>https://trid.trb.org/View/162198</link>
      <description><![CDATA[An analytic evaluation and comparison of the following candidate Buoy Position Auditing System (BPAS) configurations is presented in this report: transmission of digital Time Difference (TD) data from a Loran-C receiver on the buoy, retransmission of Loran-C pulses from the buoy, and combination of helicopter Loran-C data and helicopter-to-buoy microwave ranging data in a variable geometry solution. The candidate BPAS configurations utilize Loran-C in the differential mode. A model is developed to characterize differential Loran-C errors, accounting for the expected effect of the land/sea water conductivity interface. The error model is utilized alone, or with a microwave ranging system error model, to estimate buoy position-fix accuracy afforded by each BPAS configuration. Accuracy estimates and data on cost, complexity, and technical risk are employed to recommend a BPAS configuration for testing. It is concluded that Loran-C pulse retransmission is not a viable BPAS configuration. The variable geometry BPAS configuration is highly accurate, due to calibration of Loran-C errors by processing of redundant data, but is not presently cost-effective. The digital TD transmission BPAS configuration is recommended for testing, due to its simplicity and low cost.]]></description>
      <pubDate>Wed, 11 Dec 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/162198</guid>
    </item>
    <item>
      <title>ALTERNATE WAVEFORMS FOR A LOW-COST CIVIL GLOBAL POSITIONING SYSTEM RECEIVER</title>
      <link>https://trid.trb.org/View/162199</link>
      <description><![CDATA[This report examines the technical feasibility of alternate waveforms to perform the GPS functions and to result in less complex receivers than is possible with the GPS C/A waveform. The approach taken to accomplish this objective is (a) to identify, after a quick broad overview, a few promising waveforms, (b) to complete the architectural synthesis of a GPS system based on the new waveforms, (c) to analyze the performance of these systems in providing ranging and communication capability and (d) to assess the impact on receiver hardware and software. One conclusion is that the class of pulsed waveform, when combined with emerging matched filter technology, permits the use of a greatly simplified receiver design. A major part of the report consists of description of a pulse-based GPS design. Although very specific, the design was intended as a vehicle for performance analysis only and many refinements and alternatives within the same class are possible. Other classes of waveforms such as tone ranging and chirped FM waveforms, although adequate, do not seem superior to the present PN encoded CW waveform for GPS. Finally, if the 'alternate' waveform is simply the present C/A waveform but with a substantially increased power level, it is shown that with the present designs the performance will be greatly increased or, alternatively, performance margin can be traded for a simplified receiver implementation. (Author)]]></description>
      <pubDate>Wed, 11 Dec 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/162199</guid>
    </item>
    <item>
      <title>ACCURACY TEST OF AN AIR-TO-AIR RANGING AND BEARING SYSTEM</title>
      <link>https://trid.trb.org/View/56635</link>
      <description><![CDATA[This report covers the accuracy test of a system designed to measure, display, and record air-to-air range and bearing measurements between in-flight aircraft. Data acquired from flight tests using reference measurements described in the report showed the estimated standard deviation range of error to be 100 feet, reducible to 60 feet via software smoothing of data. The standard deviation of bearing error was 2.4 . It is concluded that the system is well within specifications. (Author)]]></description>
      <pubDate>Tue, 29 Oct 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/56635</guid>
    </item>
    <item>
      <title>3D/4D AREA NAVIGATION SYSTEM DESIGN, DEVELOPMENT AND IMPLEMENTATION. VOLUME II. SUPPORT DATA AND PROGRAM LISTINGS</title>
      <link>https://trid.trb.org/View/75426</link>
      <description><![CDATA[This volume presents the detailed support data for the 4D time control and localizer software definitions. Program listings for the final design are also presented. (Author)]]></description>
      <pubDate>Sat, 12 Oct 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/75426</guid>
    </item>
    <item>
      <title>ANALYSIS OF VISUAL DETECTION PERFORMANCE (FALL 1978 EXPERIMENT)</title>
      <link>https://trid.trb.org/View/82910</link>
      <description><![CDATA[From 11 September 1978 to 6 October 1978 a visual detection experiment was conducted in Block Island sound by the U.S. Coast Guard Research and Development Center. It was the first in a series of experiments designed to improve search planning guidance contained in the National Search and Rescue Manual. This was a controlled experiment involving 82 and 95 foot cutters, 41 and 44 foot boats, helicopters, and fixed wing aircraft searching for white 16 foot boat targets anchored at predetermined locations within the search area. Through the use of a microwave ranging system, the positions of searchers and targets could be accurately reconstructed to determine the lateral range of targets that were detected, as well as targets not detected. Thus, probability of detection versus lateral range curves could be developed, and, by integrating these curves, sweep width could be determined as well. A total of 695 detection opportunities were generated. A sophisticated binary multivariate logistic regression computer program was used to develop sweep width estimates for the environmental conditions experienced. Of the eight visual detection parameters investigated, visibility, wind speed, swell height, cloud cover, search unit type, and duration of search were determined to have a significant effect on sweep width. The sweep width is an excellent measure of search unit performance. A more rapid degradation of sweep width was found for deteriorating environmental conditions than is now predicted by the National Search and Rescue Manual. The methods used to conduct this experiment and analyze the data were found to be successful, and are recommended for future experiments.]]></description>
      <pubDate>Sun, 30 Jun 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/82910</guid>
    </item>
    <item>
      <title>THE SUSCEPTIBILITY OF REPRESENTATIVE TACAN AND DME EQUIPMENTS TO A PROPOSED, MLS L-BAND PRECISION DME SIGNAL FORMAT</title>
      <link>https://trid.trb.org/View/162930</link>
      <description><![CDATA[Measured data are presented that show the susceptibility of representative Tactical Air Navigation/Distance Measurement Equipments (TACAN/DME) to the proposed, Microwave Landing System (MLS) L-Band Precision DME (PDME) signal format. The interrogator data are examined to determine the most susceptible equipments, and the desired and undesired signal relationships that permit range and azimuth acquisition. Comments are made on the transponder data. (Author)]]></description>
      <pubDate>Wed, 12 Jun 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/162930</guid>
    </item>
    <item>
      <title>COMPARISON BETWEEN THE SURVEILLANCE PERFORMANCES OF THE AIR TRAFFIC CONTROL RADAR BEACON SYSTEM MODE OF THE MODE S AND THE AUTOMATED RADAR TERMINAL SYSTEM</title>
      <link>https://trid.trb.org/View/177190</link>
      <description><![CDATA[A test and evaluation was conducted at the Federal Aviation Administration Technical Center to compare the surveillance performance and the range and azimuth accuracy of the Air Traffic Control Radar Beacon System (ATCRBS) mode of the Mode S (formerly the Discrete Address Beacon System (DABS)) to that achieved with the existing Automated Radar Terminal System (ARTS) III. Targets of opportunity and ATCRBS-equipped Technical Center test aircraft were used in this evaluation. The 5-foot ATCRBS antenna at the Technical Center Mode S terminal sensor was used to collect data at both the Mode S and the ARTS III sensors. Data reduction and analysis tools developed by the Technical Center were used to determine sensor performance characteristics and to highlight areas for further analysis. It was concluded that the ATCRBS mode of the Mode S sensor provided improved blip scan ratio, Mode A code, and altitude reliability performance when compared to the ARTS III. The Mode S sensor also provided better range and azimuth accuracy than the ARTS III. (Author)]]></description>
      <pubDate>Tue, 28 May 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/177190</guid>
    </item>
    <item>
      <title>AN OVERVIEW OF ALTERNATIVE TECHNIQUES FOR DETERMINING POSITIONS AT SEA, WITH EMPHASIS ON APPLICABILITY OF POTENTIAL USE FOR POSITIONING BUOYS</title>
      <link>https://trid.trb.org/View/82481</link>
      <description><![CDATA[In support of a Coast Guard effort to improve the capability of field units to place buoys at their assigned locations, an assessment of the potential of alternative techniques for determining position was undertaken. The primary objective of the evaluation was to catalog, in general terms, various field survey techniques of position determination, whether presently in use or in development, with particular emphasis on the general capabilities, limitations, and application of the individual techniques for use in positioning buoys. The results of this evaluation indicate that no single method can be used to satisfy the varied buoy placement scenarios. Instead, a combination of methods (including those presently used) would be most appropriate. Furthermore, no single combined-methods system would fit all applications unless it consisted of an all-encompassing set of equipments and procedures; an impractical solution. Laser rangefinder, precision gyrocompass, radiodetermination, and satellite methods are considered to have applicability to buoy placement operations, either as stand-alone or for incorporation with a multi-sensor system. Inertial guidance and underwater acoustic methods are not considered to have practical application. (Author)]]></description>
      <pubDate>Thu, 14 Mar 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/82481</guid>
    </item>
    <item>
      <title>OBSTACLE DETECTION AND MAPPING SYSTEMS</title>
      <link>https://trid.trb.org/View/538270</link>
      <description><![CDATA[This paper discusses and evaluates an obstacle detection algorithm developed at NIST in support of the DEMO III Unmanned Ground Vehicle (UGV) program.  The algorithm is a hybrid of grid-based and sensor-based obstacle detection and mapping techniques and is implemented as a module of the integrated 4D-Realtime Control System (RCS) system.  The module consists of two sections: an obstacle detection section that processes range data read from a ladar sensor and uses this information to detect obstacles; and, a mapping section that projects obstacle points onto a grid-based representation map used to generate a traversable path for the vehicle.  The paper describes the sensors used in the 4D-RCS autonomous driving system, the laser range finder (Ladar) sensor's characteristics, the obstacle detection algorithm, and the obstacle mapping procedure. Next, the algorithm's performance on both man-made and natural obstacles is evaluated. A demonstration is provided on autonomous driving with obstacle detection and avoidance on the NIST grounds and the Nike site at speeds of up to 15 mi/h (24 km/h).]]></description>
      <pubDate>Sun, 13 Dec 1998 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/538270</guid>
    </item>
    <item>
      <title>STRUCTURAL RANGE IMAGE TARGET MATCHING FOR AUTOMATED LINK TRAVEL TIME COMPUTATION</title>
      <link>https://trid.trb.org/View/574430</link>
      <description><![CDATA[Measurement of travel time along a roadway link between two known points has historically been a task which consumed much time and manpower.  Currently, probe vehicles are driven along the link a number of times to achieve an average time measurement.  This type of approach, because of the cost and effort involved, can only be repeated on an inadequate periodic basis.  The advances in technology being applied to Intelligent Transport Systems will allow for automated Link Travel Time computation.  This paper will present a method to measure Link Travel Time by matching approximately 10% of the vehicles detected by laser-rangefinder-based sensors, such as the Autosense family of sensors developed by Schwartz Electro-Optics, at each end of the link.  An overview of the Autosense sensor will be included to illustrate the type of data being utilized by the system.  The main components of the algorithm to be presented include primitive extraction from the range data, structural matching to pair off the extracted vehicle primitives from the two sensor locations and sample set selection.  The approach utilizes a novel concept of computing the match scores for every combination of vehicle pairs before choosing the sample set to be used for travel time measurement. The pruning of the complete set of matched vehicle pairs to the most confidently matched pairs insures a more accurate time assessment.  Preliminary results show that, of the vehicles chosen by the system as sample vehicles, 99.7% are correctly matched.  Results from tests run at two sensor sites being built on State Rd 441 in the summer of 1996 will be presented.]]></description>
      <pubDate>Thu, 28 Aug 1997 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/574430</guid>
    </item>
    <item>
      <title>MULTI-LANE RANGE-IMAGING VEHICLE SENSOR</title>
      <link>https://trid.trb.org/View/574186</link>
      <description><![CDATA[Advanced vehicle sensors are needed to provide accurate information on real-time traffic conditions that can be used for incident detection, motorist advisories, and traffic management via signals, ramp meters, etc.  This paper describes a diode-laser-based vehicle detector and classifier (VDAC), which is being developed under a program for the Jet Propulsion Laboratory, that can measure the presence, speed, and three-dimensional profiles of vehicles passing beneath it within its three-lane field-of-view coverage.  The VDAC employs a rotating polygon to scan a pulsed laser rangefinder across three 12-foot-wide lanes of highway in order to measure the presence, speed, and height profiles of vehicles in all three lanes simultaneously.  The VDAC's high signal-to-noise ratio and good spatial resolution result in highly accurate traffic-parameter measurements.  Principles of sensor operation are discussed, and test results obtained at sites on a major arterial in Orlando, Florida, are presented.]]></description>
      <pubDate>Mon, 28 Jul 1997 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/574186</guid>
    </item>
    <item>
      <title>APPLICATION OF A LASER SCANNING RANGE FINDER TO THE EXTRACTION OF VEHICLE CHARACTERISTICS</title>
      <link>https://trid.trb.org/View/574189</link>
      <description><![CDATA[Non-contact optical-type axle-counting equipment has been proposed and developed, in order to improve the accuracy of vehicle type classification in non-stop electronic toll collection systems.  The number of axles of the vehicle passing through a tollgate is one of the most important parameters for vehicle classification in Japan.  This equipment, based on the technique of trigonometric laser scanning range finder without physical contact with objects, is advantageous for both high-speed response and high durability; and sequentially produces range and gray images simultaneously.  In spite of optical disturbances, the active-sensing with the collimated laser beam ensures the acquisition of highly accurate range and contrast information on any object.  Because this equipment is installed in a roadside, the equipment requires no large-scale road construction such as cutting the road surface for equipment installation, and can be mounted onto even elevated bridges in a short period.  Equipment developed is capable of detecting not only the axle's presence but the size of wheel, the traveling direction of the vehicle, etc., from those images.  Elementary tests including axle-counting were successfully carried out with present equipment at a tollgate.  In the future, this multi-functional sensing method will be applicable for intelligent vehicle classification.]]></description>
      <pubDate>Mon, 28 Jul 1997 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/574189</guid>
    </item>
  </channel>
</rss>