William H. Harman

Measurements of ADS-B Extended Squitter performance in the Los Angeles basin region

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 Squirter performance in current and future scenarios.

Radar images of Logan Airport and application in automated aircraft tracking

To enhance safety and expedite aircraft traffic control at airports, the Federal Aviation Administration (FAA) is in the process of developing automation aids for controllers and pilots. These automation improvements depend on reliable surveillance of the airport traffic, in the form of computerized target reports for all aircraft. One means of surveillance of the airport is primary radar. A short range radar of this type is called airport surface detection equipment or (ASDE). Lincoln Laboratory is participating in this development program by testing a system of surveillance and automation aids at Logan International Airport in Boston, Mass. This work is sponsored by the FAA. This paper describes the radar equipment being used for surface surveillance at Logan Airport and the characteristics of the radar images it produces. Techniques for automatic tracking of this radar data are also described along with a summary of the tracking performance that has been achieved. Two companion papers in this session relate to this same radar surveillance and provide more in-depth descriptions of the radar processing.

ADS-B airborne measurements in Frankfurt

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 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).

Target detection using radar images of an airport surface

Automation aids which increase the efficiency of the controller and enhance safety are being sought by the Federal Aviation Administration (FAA). This paper describes the target detection algorithms developed by the MIT Lincoln Laboratory as part of the airport surface traffic automation (ASTA) and runway surface safety light system (RSLS) programs sponsored by the FAA that were demonstrated at Logan International Airport in Boston, Mass. from September 1992 through December 1993. A companion paper to this conference describes the ASTA and RSLS system demonstration. Another companion paper describes the tracking algorithms. Real-time, parallel processing implementations of these surveillance algorithms are written in C++ on a Silicon Graphics Inc. Unix multiprocessor. The heavy reliance on commercial hardware, standard operating systems, object oriented design, and high-level computer languages allows a rapid transition from a research environment to a production environment.

TCAS surveillance performance analysis

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 throughout the National Airspace System (NAS). This paper uses a high fidelity simulation to characterize TCAS surveillance performance in six high traffic terminal environments. Transponder utilization due to TCAS and TCAS surveillance range are compared with the interference limiting design requirements. 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.

Connected components and temporal association in airport surface radar tracking

MIT Lincoln Laboratory, under sponsorship of the FAA, has installed a modified Raytheon pathfinder x-band marine radar at Logan Airport in Boston, Mass. and has developed a real- time surveillance system based on the pathfinders digitized output. The surveillance system provides input to a safety logic system that will ultimately activate a set of runway status lights. This paper describes the portion of the surveillance system following the initial clutter- rejecting preprocessing, described elsewhere. The overall mechanism can be simply described as a temporal constant false alarm rate front end followed by binary morphological operations including connected components feeding a scan-to-scan tracker. However, a number of refinements have been added leading to a system which is close to being fieldable. Both the special difficulties and the current solutions are examined. The radar hardware as well as the computational environment are discussed. An overview of the clutter rejection preprocessing is given, as well as physical and processing related challenges associated with the data. Algorithmic description of the current system is presented and its real-time implementation outlined. Performance statistics and envisioned algorithmic improvements are presented.