Publications
Measurements of the 1030 and 1090 MHz environments at JFK International Airport
September 12, 2012
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-390
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Summary
Measurements of signals in the 1030 and 1090 MHz frequency bands have been made by MIT Lincoln Laboratory in the last several years, previously in the Boston area and most recently in April 2011, at JFK International Airport near New York City. This JFK measurement activity was performed as a part of the Lincoln Laboratory Traffic Alert and Collision Avoidance System (TCAS) work for the Federal Aviation Administration (FAA) and is the subject of this report. This report includes: 1) Overall characteristics of the 1030/1090 MHz environments, 2) Analysis of the TCAS air-to-air coordination process, 3) Examination of 1090 MHz Extended Squitter transmissions for use in TCAS, 4) Assessment of the extent and impact of TCAS operation on the airport surface.
Summary
Measurements of signals in the 1030 and 1090 MHz frequency bands have been made by MIT Lincoln Laboratory in the last several years, previously in the Boston area and most recently in April 2011, at JFK International Airport near New York City. This JFK measurement activity was performed as a...
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Lincoln Laboratory 1030/1090 MHz monitoring, March-June 2010
November 15, 2011
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-372
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Traffic Alert and Collision Avoidance System (TCAS) behavior in New England airspace is being monitored and analyzed, making use of an omni-directional 1030/1090 MHz receiver. The receiver system, located in Lexington, Massachusetts, and operated by MIT Lincoln Laboratory, is used to record data for subsequent analysis in non-real-time. This is the second report of MIT Lincoln Laboratory 1030/1090 MHz monitoring, covering the period March through June 2010. There are three main areas of study: 1. 1030 MHz data related to TCAS air-to-air coordination and other communications, 2. 1030 and 1090 MHz data related to TCAS surveillance, and 3. 1090 MHZ Extended Squitter data, i.e., the Mode S implementation of Automatic Dependent Surveillance-Broadcast (ADS-B). In addition to a summary of results, this report answers specific questions raised during the previous 2009 analysis and attempts to provide insights into the meaning of the data with respect to TCAS operation. This four-month period will be used to baseline 1030/1090 MHz activity in the New England area. Future plans call for the 1030/1090 MHz receiver to be moved so that limited data recording can be performed at various TCAS RA monitoring system (TRAMS) sites throughout the NAS.
Summary
Traffic Alert and Collision Avoidance System (TCAS) behavior in New England airspace is being monitored and analyzed, making use of an omni-directional 1030/1090 MHz receiver. The receiver system, located in Lexington, Massachusetts, and operated by MIT Lincoln Laboratory, is used to record data for subsequent analysis in non-real-time. This is...
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Triangle TCAS antenna
March 31, 2011
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-380
Summary
The Traffic Alert and Collision Avoidance (TCAS) provides a pilot display showing the range and bearing of nearby aircraft. TCAS obtains the bearing information by using an angle-of-arrival antenna. In the development of TCAS at Lincoln Laboratory, the first airborne tests were conducted using an Adcock antenna, which is a small square array of four monopole elements. This report describes an alternative antenna for TCAS, using three elements in the shape of a triangle. It is shown that the triangle antenna is less sensitive to receiver noise, and that improvement factor is about 10 dB.
Summary
The Traffic Alert and Collision Avoidance (TCAS) provides a pilot display showing the range and bearing of nearby aircraft. TCAS obtains the bearing information by using an angle-of-arrival antenna. In the development of TCAS at Lincoln Laboratory, the first airborne tests were conducted using an Adcock antenna, which is a...
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MIT Lincoln Laboratory TCAS surveillance performance
December 28, 2010
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-370
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The Traffic Alert and Collision Avoidance System (TCAS) Version 7 surveillance requirements were developed in the mid-1990s with the use of limited radar data. Recently, a more comprehensive radar data source has become available, enabling a thorough analysis of TCAS surveillance performance throughouth the National Airspace System (NAS). This paper characterizes six high traffic terminal environments over three months. A busy one hour period was selected from each location for density and equipage measurements. This paper then describes the use of a high fidelity simulation to characterize TCAS surveillance performance in the isx locations. Transponder utilization due to TCAS and TCAS surveillance range are compared with the design requirements, including interference limiting specifications. The effect of TCAS surveillance activity on Air Traffic Control (ATC) ground radar performance is also investigated. Results indicate that the surveillance algorithms perform as intended and that TCAS has a minimal impact on ground radar. Areas of concern are noted for future investigation.
Summary
The Traffic Alert and Collision Avoidance System (TCAS) Version 7 surveillance requirements were developed in the mid-1990s with the use of limited radar data. Recently, a more comprehensive radar data source has become available, enabling a thorough analysis of TCAS surveillance performance throughouth the National Airspace System (NAS). This paper...
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ADS-B Airborne Measurements in Frankfurt
October 27, 2002
Conference Paper
Published in:
21st AIAA/IEEE Digital Avionics Systems Conf., 27-31 October 2002, pp. 3.A.3-1 - 3.A.3-11.
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Automatic Dependent Surveillance-Broadcast (ADS-B) was the subject of airborne testing in Frankfurt, Germany in May 2000. ADS-B is a system in which latitude-longitude information is broadcast regularly by aircraft, so that receivers on the ground and in other aircraft can determine the presence and accurate locations of the transmitting aircraft. In addition to the latitude and longitude, ADS-B transmissions include altitude, velocity, aircraft address, and a number of other items of optional information. The tests in Germany were aimed at assessing the performance of Mode S Extended Squitter, which is one of several possible implementations of ADS-B. Extended Squitter uses a conventional Mode S signal format, specifically the 112-bit reply format at 1090 MHz, currently being used operationally for air-to-ground communications and air-to-air coordination in TCAS (Traffic Alert and Collision Avoidance System).
Summary
Automatic Dependent Surveillance-Broadcast (ADS-B) was the subject of airborne testing in Frankfurt, Germany in May 2000. ADS-B is a system in which latitude-longitude information is broadcast regularly by aircraft, so that receivers on the ground and in other aircraft can determine the presence and accurate locations of the transmitting aircraft...
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Measurements of ADS-B extended squitter performance in the Los Angeles basin region
October 7, 2000
Conference Paper
Published in:
19th AIAA/IEEE Digital Avionics Systems Conf., Vol. 2, 7-13 October 2000, pp. 7.B.1-1 - 7.B.1-8.
Summary
The Los Angeles Basin ADS-B Measurement Trials provided a quantitative assessment of the existing interference environment at 1090 MHz and the surveillance performance of Mode S Extended Squitter in that environment. Redundancy in the measurement equipment and in the flight configurations chosen during the trials provided extensive cross checking capability, and greatly increased the integrity of the results. ATCRBS reply rates as high as 40,000/second above -90 dBm were measured. The corresponding aircraft distribution and 1030 MHz interrogation rates correlated well with these measurements. A wide range of scenarios were captured to measure the airborne and ground-based reception of ADS-B Extended Squitters emitted by airborne sources. Air-to-air ranges of greater than 100 nmi were routinely observed, and comparison with ADS-B MASPS requirements showed that all airborne requirements were met in the scenarios flown. Air-to-ground reception rates were routinely better than the update rates provided by either en route or terminal radars at ranges beyond 150 nmi. Ground-to-air (uplink) performance was adequate to support transmission of ADS-B or other information in broadcast formats within approximately 60 nmi of the ground station. Finally, these measurements are a valuable source of validation and refinement data for the various models used to predict Extended Squitter performance in current and future scenarios.
Summary
The Los Angeles Basin ADS-B Measurement Trials provided a quantitative assessment of the existing interference environment at 1090 MHz and the surveillance performance of Mode S Extended Squitter in that environment. Redundancy in the measurement equipment and in the flight configurations chosen during the trials provided extensive cross checking capability...
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Techniques for improved reception of 1090 MHz ADS-B signals
October 31, 1998
Conference Paper
Published in:
17th DASC: Proc. of the 17th. Digital Avionics Systems Conf., 31 October - 7 November 1998, Vol. 2, pp. G25-1 - G25-9.
Summary
The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters and the associated position and status. Squitter reception includes the detection of the Mode S 1090 MHz waveform preamble, declaration of the bit and confidence values, error detection, and (if necessary) error correction. The current techniques for squitter reception are based upon methods developed for use in Mode S narrow-beam interrogators and for ACAS. In both of these applications, the rate of Mode NC fruit that is stronger than the Mode S waveform is relatively low, nominally less than 4,000 fruit per second. Extended squitter applications now include long range (up to 100 nmi) air-air surveillance in support of free flight. This type of surveillance is sometimes referred to as Cockpit Display of Traffic Information (CDTI). In high density environments, it is possible to operate with fruit rates of 40,000 fruit per second and higher. Operation of extended squitter in very high ModeNC fruit environments has led to the need to re-evaluate squitter reception techniques to determine if improved performance is achievable. The purpose of this paper is to provide a summary of work in progress to investigate improved squitter reception techniques. Elements of improved squitter reception being investigated include (1) the use of amplitude to improve bit and confidence declaration accuracy, (2) more capable error correction algorithms, and (3) more selective preamble detection approaches.
Summary
The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters...
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Beacon radar and TCAS reply rates: airborne measurements in the 1090 MHz band
January 29, 1997
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-256
Summary
The Federal Aviation Administration (FAA) is in the process of developing Automatic Dependent Surveillance Broadcast (ADS-B) techniques. In one candidate system, GPS-Squitter, each aircraft periodically broadcasts messages, called "squitters," that report the aircraft's identification, position, and velocity. The position and velocity information may be obtained from the Global Positioning System (GPS) or some other navigation device. Reception of squitters can be used for several purposes, including surveillance of airborne aircraft by a ground station, surveillance of aircraft on the airport surface, and air-to-air surveillance... In developing the new system, it is necessary to know the rates of existing signal transmissions in the 1030 and 1090 MHz frequency bands, which are the beacon-radar and TCAS interrogation channels. The GPS-Squitter would be transmitted in the 1090 MHz band, like a reply. A key issue is the possibility of interference to squitter reception from existing signals in the 1090 MHz band....To validate these initial calculations, Lincoln Laboratory has made direct measurements of the rates of existing transmissions in both bands. These signals consist mainly of interrogations in the 1030 MHz band and replies in the 1090 MHz band. This report focuses on airborne measurements that have been made at 1090 MHz. (Not complete)
Summary
The Federal Aviation Administration (FAA) is in the process of developing Automatic Dependent Surveillance Broadcast (ADS-B) techniques. In one candidate system, GPS-Squitter, each aircraft periodically broadcasts messages, called "squitters," that report the aircraft's identification, position, and velocity. The position and velocity information may be obtained from the Global Positioning System...
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Beacon radar and TCAS interrogation rates: airborne measurements in the 1030 MHz band
May 2, 1996
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-239
Summary
Airborne measurements were made of the rates of beacon-radar interrogations and suppressions in the 1030 MHz band. These measurements were undertaken in order to provide a basis for interference analysis of the proposed system of GPS-Squitter. The measurements were made during a flight along the East Coast, including New York, Philadelphia, Baltimore, and Washington. Measurements were also made at Atlanta and in the Dallas Fort Worth area. Results were given in a form that shows the rates of interrogations and suppressions as a function of time and location of the aircraft. Interrogations are also separated into those that were transmitted by ground-based interrogators and those that were transmitted by airborne TCAS equipment. Mode S interrogations were also separated from other modes. The number of TCAS aircraft in the vicinity was also measured during the flights. The results indicate that the rates of interrogations and suppressions were consistent in most respects from location to location. The rates Mode A and C interrogations from the ground were consistently less than 100 per second with two brief exceptions. Previous measurements had indicated a trend of decreasing interrogation rates with time since the early 1970's. The new measurements support this observation and indicate that the trend has continued.
Summary
Airborne measurements were made of the rates of beacon-radar interrogations and suppressions in the 1030 MHz band. These measurements were undertaken in order to provide a basis for interference analysis of the proposed system of GPS-Squitter. The measurements were made during a flight along the East Coast, including New York...
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Runway status light system demonstration at Logan Airport
October 12, 1995
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-206
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The Runway Status Light System (RSLS), developed under the FAA's Airport Surface Traffic Automation (ASTA) program, is intended to help reduce the incidence of runway incursions and airport surface accidents. It will do so by providing a preventive, back-up system of automatically controlled lights on the airport surface that inform pilots when runways are unsafe for entry or takeoff, and by providing controllers with enhanced surface radar displays. This report documents a proof-of-concept evaluation of the RSLS at Boston's Logan Airport. It details the methods used to provide the necessary surface surveillance and safety logic to allow a computer to operate the runway status lights and associated controller displays without human assistance. The system was installed and tested off-line at Boston's Logan Airport using an inexpensive commercial marine radar as a primary surveillance source. The system operated live and in real time but the runway status lights were not physically installed. They were displayed on a scale model of Logan Airport located in a demonstration room that had a good view of the airport. This allowed visual comparison between the actual aircraft and the resulting lights and displays. In addition to providing a convincing demonstration of the system, real-timing viewing of the aircraft movement was an important aid in the development of the surveillance processing and safety logic software. Surveillance performance and runway status light operational performance were evaluated quantitatively. The probability of tracking an aircraft in movement areas with line-of-sight coverage was better than 98%. The false track rate was about four per hour, and the surveillance jitter was about 1 meter rms. From an operational point of view, had there been real lights on the field, it appears that they would have provided the intended safety back-up with little impact on airport capacity or controller and pilot workload, Only once in 15 minutes would the pilot population have observed a light in an incorrect state for more than four seconds. From the point of view of a specific cockpit crew, only once in 36 operations would a runway status light have been seen in an incorrect state for more than four seconds, and, furthermore, only once in 50 operations would light illuminations have interfered with normal, safe traffic flow. These are encouraging results for a system in an early demonstration phase because significant improvement is possible in all of these performance measures. Specific suggestions for improvement are included in this document.
Summary
The Runway Status Light System (RSLS), developed under the FAA's Airport Surface Traffic Automation (ASTA) program, is intended to help reduce the incidence of runway incursions and airport surface accidents. It will do so by providing a preventive, back-up system of automatically controlled lights on the airport surface that inform...
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