Publications
Multifunction phased array radar (MPAR) spectral usage analysis
July 24, 2012
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-395
Summary
This report addressed two technical risks associated with replacing current air traffic and weather surveillance radars with a single type of multifunction phased array radar (MPAR). The first risk is whether radio spectrum usage would increase with the MPAR network and whether the allocated band will have enough spectral space. This question is addressed in two steps. First, single-radar spectrum usage is estimated based on certain assumptions regarding the radar design. Second, locations based on a previous radar placement study are used together with a terrain-dependent propagation model to compute the number of frequency channels needed at each site. We conclude that the overall spectrum usage is likely to increase with MPAR, but that the targeted window in S band will be able to accommodate the occupancy at all sites. The second risk is whether self-interference will limit the ability of the MPAR to operate asynchronously and adaptively on different antenna faces. This question is addressed by employing a simple bistatic ground clutter model to characterize the interference between adjacent faces. We conclude that some interference is unavoidable, but it would likely only occur during times when a transmit beam is at its maximum off-broadside angle (~2% of the time).
Summary
This report addressed two technical risks associated with replacing current air traffic and weather surveillance radars with a single type of multifunction phased array radar (MPAR). The first risk is whether radio spectrum usage would increase with the MPAR network and whether the allocated band will have enough spectral space...
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Elementary surveillance (ELS) and enhanced surveillance (EHS) validation via Mode S secondary radar surveillance
April 25, 2008
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-337
Summary
Several applications of the Mode S data link are currently being implemented and equipage requirements have been issued in countries around the world. Elementary surveillance (ELS) and enhanced surveillance (EHS) applications have been mandated in Europe with full equipage of all aircraft in the airspace required by 2009. Exemptions to the ELS requirement include aircraft that will be out of service by 31 December 2009, and aircraft undergoing flight-testing, delivery, or transit into or out of maintenance bases. Transport type aircraft (defined as having a maximum take-off weight in excess of 250 knots) are to be equipped to support ELS and EHS. Exemptions to the requirements for EHS include those listed above for ELS and: a- fighter and training aircraft; b- rotary-wing aircraft; c- existing/older transport type aircraft undergoing avionics upgrades which will then support ELS/EHS; and d- aircraft types granted special exemptions (e.g., B1-B, B2-A, and B-52H bombers). [not complete]
Summary
Several applications of the Mode S data link are currently being implemented and equipage requirements have been issued in countries around the world. Elementary surveillance (ELS) and enhanced surveillance (EHS) applications have been mandated in Europe with full equipage of all aircraft in the airspace required by 2009. Exemptions to...
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Guidance material for Mode S-specific protocol application avionics
June 4, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-334
Topic:
R&D area:
R&D group:
Summary
This ATC report presents guidance material for the use of "Ground-Initiated Comm. B" (GICB) register set contained in a Mode S transponder. The guidance material is intended to provide assistance for implementers of Mode S avionics installations. A common summary of the requirements and specifications for Mode S GICB transponder register data link applications is developed. While this ATC report focuses primarily on the "Elementary Surveillance" (ELS), "Enhanced Surveillance" (EHS), and "Automatic Dependent Surveillance-Broadcast" (ADS-B) applications, guidance information is also provided for general transponder configuration and architecture of other Mode S functions employing the GICB register set. Although the information contained in this ATC report is drawn from a number of approved national and international standards, it is not intended to replace or supersede those standards documents. In the event of a conflict or contradiction between this ATC report and any approved standards (see references 1 through 6), the approved standard takes precedence and the reader is encouraged to contact the authors of this document. Reference 4 is the most-recent and complete specification for the Mode S register contents. For ease of reference, the relevant Mode S register images have been duplicated in Appendix A of this report.
Summary
This ATC report presents guidance material for the use of "Ground-Initiated Comm. B" (GICB) register set contained in a Mode S transponder. The guidance material is intended to provide assistance for implementers of Mode S avionics installations. A common summary of the requirements and specifications for Mode S GICB transponder...
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Surveillance improvement algorithms for Airport Surface Detection Equipment Model X (ASDE-X) at Dallas-Fort Worth Airport
April 20, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-333
Summary
Operational testing of the Runway Status Lights (RWSL) system at the Dallas-Fort Worth (DFW) airport has detected a number of cases where faults in the ASDE-X/DFW surveillance data have led to erroneous operation of the status lights. Among the surveillance problems noted during testing at DFW were: (a) false tracks, (b) track positional jumps to false locations, (c) Mode S track splits, (d) ATCRBS track splits, (e) invalid Mode C altitudes, (f) invalid track velocities, and (g) spurious Mode 3/a 06078 code tracks. The RWSL surveillance improvement algorithms package in this document is placed between the ASDE-X/DFW surveillance data source and the RESL safety logic. The surveillance improvement algorithms perform a variety of reasonableness and consistency checks on the input data and set validity flags and report status values for each input report which are then passed on to the RWSL safety logic. These flags and status values allow the RWSL to ignore erroneous reports and to avoid using questionable report components in the subsequent RWSL logic. This document illustrates the performance of the RWSL surveillance improvement algorithms package with examples from DFW analysis. It is shown that the RWSL surveillance improvement algorithms package substantially reduces the impact of the known ASDE-X/DFW surveillance anomalies on the performance of the RWSL safety logic. The RWSL surveillance improvement algorithms package may also host future algorithms necessary to mitigate further problems that might be detected in the surveillance data.
Summary
Operational testing of the Runway Status Lights (RWSL) system at the Dallas-Fort Worth (DFW) airport has detected a number of cases where faults in the ASDE-X/DFW surveillance data have led to erroneous operation of the status lights. Among the surveillance problems noted during testing at DFW were: (a) false tracks...
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ASR-9 Processor Augmentation Card (9-PAC) phase II scan-scan correlator algorithms
April 26, 2001
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-298
Summary
This report documents the scan-scan correlator (tracker) algorithm developed for Phase II of the ASR-9 Processor Augmentation Card (9-PAC) project. The improved correlation and tracking algorithms in 9-PAC Phase II decrease the incidence of false-alarm tracks and increase the detection of real aircraft. The tracker processing for 9-PAC Phase II defined in this document builds upon the prototype 9-PAC Phase II tracker describedin ATC-245. Tracker algorithms from Mode S (ATC-65) are also used in Phase II. This document describes the three main processing tasks of the tracker: initialization, input/output, and the actual correlation/tracking. The tracker itself is further broken down into four main functions: report-to-track association, report-to-track correlation, track update, and track initiation. Each of these functions is described in detail and is further broken down into sub-functions. In addition to the algorithm descriptions, the 9-PAC Phase II tracker system requirements are reviewed, and main data structures used in the 9-PAC Phase II tracker are defined.
Summary
This report documents the scan-scan correlator (tracker) algorithm developed for Phase II of the ASR-9 Processor Augmentation Card (9-PAC) project. The improved correlation and tracking algorithms in 9-PAC Phase II decrease the incidence of false-alarm tracks and increase the detection of real aircraft. The tracker processing for 9-PAC Phase II...
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Open system protocols for aviation data link applications
October 7, 2000
Conference Paper
Published in:
19th AIAA/IEEE Digital Avionics Systems Conf., Vol. 2, 7-13 October 2000.
Summary
This paper will discuss the application of "open system" communications protocols in the design and implementation of data link applications for aviation. The term "open system" in this paper refers to a set of communications protocols whose design specification is readily open to the user community, usually via publication by an international standards body. Such open system standards tend to encourage widespread implementation and enhancement of the communications protocols defined in the open standards. Ready availability of well-tested implementations helps to keep the costs of open systems low. Interoperability of equipment is enhanced by the use of open systems, as is the ease of system extensibility. In some cases, system communications infrastructures to support the open system may already be in place (e.g. the Internet). Data link applications in aviation are increasing at an accelerating rate. Whether for air traffic control, airline operations, or improved pilot situational awareness, data link systems are required for many existing and future functions in aviation. Many aviation data link designs have been proposed and demonstrated over the years. A drawback to most of these designs is their ad hoc nature. It is difficult to combine the various aviation data links into a coherent overall system architecture. Since each aviation data link was specialized for a specific task or application, there is little commonality of design, nor is there much opportunity for software/hardware reuse in ground or avionics equipment. Each aviation data link has required its own separate system infrastructure - leading to considerable overlap, complexity, and expense. At the same time, the Internet community has seen explosive growth in both the number of Internet users and the types of Internet system applications. Much of this growth may be tied to the "open system" nature of the Internet communications protocols which allows for straightforward implementation of Internet applications. It is difficult to buy a computer today that doesn't have an Internet protocol stack in its system software. Extremely inexpensive Internet implementations are in everything from microwave ovens to laptops. The Internet's dramatic growth is an indicator of the power of "open system" architecture to encourage development of communications applications. This paper will show how the use of suitable open system communications protocols can help to bring increased efficiency and lower-cost equipment to aviation data link systems.
Summary
This paper will discuss the application of "open system" communications protocols in the design and implementation of data link applications for aviation. The term "open system" in this paper refers to a set of communications protocols whose design specification is readily open to the user community, usually via publication by...
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Rotating a weather map
June 1, 1999
Journal Article
Published in:
Dr. Dobb's J., Vol. 24, No. 6, June 1999, pp. 80-88.
Summary
Introduction: I was recently part of a project developing a system for aircraft pilots to access the national ground weather-radar database while in flight. This weather-radar graphical database is generated from the outputs of the FAA and National Weather Service network of radars covering the continental United States and is updated every five minutes. Each pixel in the database covers a square measuring two kilometers (about one nautical mile) on a side. The content of each data pixel is a measure of the radar reflectivity measured at that location - radar reflectivity is proportional to the water content in the atmosphere (the precipitation rate). This graphical database is available through several commercial vendors - it's what you see displayed on The Weather Channel or during typical TV weather reports. Our system, on the other hand, provides a low-speed digital datalink connection from an FAA ground computer to an avionics computer/display located in the aircraft cockpit.
Summary
Introduction: I was recently part of a project developing a system for aircraft pilots to access the national ground weather-radar database while in flight. This weather-radar graphical database is generated from the outputs of the FAA and National Weather Service network of radars covering the continental United States and is...
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Encoding approaches for data link transmission of weather graphics
December 10, 1993
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-205
Summary
To provide pilots with necessary information to make informed decisions on the avoidance of hazardous weather and to maintain situational awareness of the weather conditions, the FAA is actively developing the capability to provide real-time graphical weather information to aircraft through the use of bandwidth-limited data links such as Mode S. The information content of weather images and the restricted bandwidth of the transmission channel require that the images be extensively compressed. This paper provides the results of a study concerning the applicability of various data compression algorithms to the weather image problem. Its conclusion is that the Polygon-Ellipse Algorithm developed at Lincoln Laboratory provides the best combination of compression, computational efficiency, and image quality for the encoding of weather images over the Mode S data link or other similarly bit-limited data links.
Summary
To provide pilots with necessary information to make informed decisions on the avoidance of hazardous weather and to maintain situational awareness of the weather conditions, the FAA is actively developing the capability to provide real-time graphical weather information to aircraft through the use of bandwidth-limited data links such as Mode...
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