Publications
Comparison of active TCAS slant range measurements with interpolated passive position reports for use in hybrid surveillance applications - measurements from the June 1999 Los Angeles Basin flight tests
October 17, 2000
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-294
Summary
Traffic Alert and Collision Avoidance System (TCAS) hybrid surveillance is a technique that makes use of both active surveillance data from the interrogation reply sequence and passive position estimates received from Mode S extended squitters. This technique allows TCAS to use passive surveillance once the data have been validated by comparison with active data. The maximum allowable range difference for validation specified by the International Civil Aviation Organization (ICAO) is 200 meters. Data from twenty encounters recorded during flight tests conducted in the Los Angeles Basin in June 1999 were analyzed. The results show that the ICAO specified limits were never exceeded and serve to validate the 200 meter limit.
Summary
Traffic Alert and Collision Avoidance System (TCAS) hybrid surveillance is a technique that makes use of both active surveillance data from the interrogation reply sequence and passive position estimates received from Mode S extended squitters. This technique allows TCAS to use passive surveillance once the data have been validated by...
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The Lincoln speaker recognition system: NIST EVAL2000
October 16, 2000
Conference Paper
Published in:
6th Int. Conf. on Spoken Language, ICSLP, 16-20 October 2000.
Topic:
R&D area:
Summary
This paper presents an overview of the Lincoln Laboratory systems fielded for the 2000 NIST speaker recognition evaluation (SRE00). In addition to the standard one-speaker detection tasks, this year's evaluation, as in 1999, included multi-speaker spokes dealing with detection, tracking and segmentation. The design approach for the Lincoln system in SRE00 was to develop a set of core one-speaker detection and multi-speaker clustering tools that could be applied to all the tasks. This paper will describe these core systems, how they are applied to the SRE00 tasks and the results they produce. Additionally, a new channel normalization technique known as handset-dependent test-score norm (HTnorm) is introduced.
Summary
This paper presents an overview of the Lincoln Laboratory systems fielded for the 2000 NIST speaker recognition evaluation (SRE00). In addition to the standard one-speaker detection tasks, this year's evaluation, as in 1999, included multi-speaker spokes dealing with detection, tracking and segmentation. The design approach for the Lincoln system in...
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A statistical analysis of approach winds at capacity-restricted airports
October 7, 2000
Conference Paper
Published in:
19th AIAA/IEEE Digital Avionics Systems Conf., Vol. 1, 7-13 October 2000, pp. 3.E.4-1 - 3.E.4-7.
Summary
Many major airports in the U.S. rely on simultaneous approaches to closely-spaced parallel (CSP) runways to maintain a high airport acceptance rate. During Visual Meteorological Conditions (VMC), aircraft are able to utilize both runways by making side-by-side landings and are able to meet the demands of heavy volume. However, when conditions deteriorate to marginal-VMC or Instrument Meteorological Conditions (IMC), side-by-side approaches are not possible due to the inherent safety concerns associated with lowered ceilings and visibilities. This situation is severely limiting to an airport's capacity and can create large delays and increased costs. Various ideas have been suggested that would facilitate the simultaneous use of CSP runways during low ceiling and visibility (LCV) conditions at capacity-restricted airports. This report addresses the specific scenario of a pair of approaching aircraft being staggered by some longitudinal distance. This situation alleviates the collision hazard presented by LCV conditions, but also introduces the hazard of a wake vortex encounter, particularly if the following aircraft is downwind of the leading aircraft.
Summary
Many major airports in the U.S. rely on simultaneous approaches to closely-spaced parallel (CSP) runways to maintain a high airport acceptance rate. During Visual Meteorological Conditions (VMC), aircraft are able to utilize both runways by making side-by-side landings and are able to meet the demands of heavy volume. However, when...
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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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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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Multilateration system development history and performance at Dallas/Ft. Worth Airport
October 7, 2000
Conference Paper
Published in:
19th AIAA/IEEE Digital Avionics Systems Conf., Vol. 1, 7-13 October 2000, pp. 2.E.1-1 - 2.E.1-8.
Summary
The long search for a method to provide accurate secondary radar beacon surveillance with aircraft ID over the whole airport surface has succeeded, using the Mode S squitter and whisper shout technologies to provide signal sources on which to make multilateration position measurements. The resulting multilateration system will greatly improve the situational awareness of the ground controllers, and provide inputs to automation functions, providing improvements in airport safety and capacity.
Summary
The long search for a method to provide accurate secondary radar beacon surveillance with aircraft ID over the whole airport surface has succeeded, using the Mode S squitter and whisper shout technologies to provide signal sources on which to make multilateration position measurements. The resulting multilateration system will greatly improve...
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SOI wafer selection for CCD/SOI-CMOS technology [Abstract]
October 2, 2000
Conference Paper
Published in:
2000 IEEE Int. SOI Conf. Proc., 2-5 October 2000, pp. 136-137.
Summary
We have developed a process that monolithically integrates fully depleted SOI CMOS (FDSOI) with high-performance CCD image sensors. This integrated technology that enables charged-coupled devices (CCD's) to be in close proximity to, yet isolated from, FDSOI circuits. This approach exploits both the advantages of FDSOI (fast, low-power CMOS with potentially enhanced radiation performance) and those of CCD's (high quantum efftciency, low noise, and architectural flexibility). This 3.3 V, 0.3 mu m CCD/FDSOI-CMOS technology thus enables fabrication of low-power, compact imaging systems. Material requirements for CCD imagers are perhaps the most stringent of any device and require special attention to the quality of the bulk or handle wafer. We report here characterization of various SOI handle wafers for use in fabrication of bulk imaging devices.
Summary
We have developed a process that monolithically integrates fully depleted SOI CMOS (FDSOI) with high-performance CCD image sensors. This integrated technology that enables charged-coupled devices (CCD's) to be in close proximity to, yet isolated from, FDSOI circuits. This approach exploits both the advantages of FDSOI (fast, low-power CMOS with potentially...
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Learning from incidents - what the machine can learn
October 2, 2000
Conference Paper
Published in:
Int. Society of Air Safety Investigators Conf., ISASI, 2-6 October 2000.
Summary
Aviation weather refers to any type of weather that can affect the operation of an aircraft – anything from a brief delay in departure to a catastrophic accident during flight. Wind shear and events associated with convective weather were recognized as an aviation hazard long before Dr. Theodore Fujita began publishing his now-famous treatises. On July 28, 1943, American Airlines Flight 63 from Cleveland, Ohio, USA to Nashville, Tennessee crashed after the pilot lost control of the Douglas DC3. The pilots and numerous passengers were fatally injured. The aircraft was destroyed by impact and post crash fire. The weather report at the time included warnings for storms, heavy rain, lightning and severe turbulence. The Civil Aeronautics Board found that the probable cause was a loss of control of the aircraft due to unusually severe turbulence and violent downdraft caused by a thunderstorm. In the ten-year period from 1987 through 1996, 24% of all U.S. accidents were judged to be "weather related". For the twenty-year period 1976 to 1996 fully 43% of U.S. accidents were judged to have involved wind or wind shear, and 2.3 % thunderstorm, although the two data elements are not mutually exclusive. In the U.S., approximately 82% of accidents are general aviation; the rest are air carriers and commuters of various types. When general aviation accidents are negated, and only air carriers are considered, wind and wind shear issues account for 9.5% of accidents. The Weather Systems Processor (WSP) has been developed to reduce the impact of severe weather conditions on air traffic by providing information concerning weather conditions in the airport terminal environment. WSP provides warnings to air traffic controllers and supervisors of hazardous wind shear and microburst events in the terminal area, forecasts the arrival of gust fronts, and tracks thunderstorms, providing a complete picture of current and future terminal area hazardous weather conditions that may impact runway and airport usage. Common weather situation awareness allows Terminal Approach, Tower Controllers and other traffic management personnel to jointly plan with confidence and safely manage more arrivals and departures with less delay. Knowledge of the location, severity and movement of hazardous weather allows dynamic adjustments to be made in routing aircraft to runways, approach and departure corridors, terminal arrival and departure transition areas (i.e. gate-posts) and other air routes.
Summary
Aviation weather refers to any type of weather that can affect the operation of an aircraft – anything from a brief delay in departure to a catastrophic accident during flight. Wind shear and events associated with convective weather were recognized as an aviation hazard long before Dr. Theodore Fujita began...
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Analysis and results of the 1999 DARPA off-line intrusion detection evaluation
October 2, 2000
Conference Paper
Published in:
Proc. Recent Advances in Intrusion Detection, RAID, 2-4 October 2000, pp. 162-182.
R&D area:
R&D group:
Summary
Eight sites participated in the second DARPA off-line intrusion detection evaluation in 1999. Three weeks of training and two weeks of test data were generated on a test bed that emulates a small government site. More than 200 instances of 58 attack types were launched against victim UNIX and Windows NT hosts. False alarm rates were low (less than 10 per day). Best detection was provided by network-based systems for old probe and old denial-of-service (DOS) attacks and by host-based systems for Solaris user-to-root (U2R) attacks. Best over-all performance would have been provided by a combined system that used both host- and network-based intrusion detection. Detection accuracy was poor for previously unseen new, stealthy, and Windows NT attacks. Ten of the 58 attack types were completely missed by all systems. Systems missed attacks because protocols and TCP services were not analyzed at all or to the depth required, because signatures for old attacks did not generalize to new attacks, and because auditing was not available on all hosts.
Summary
Eight sites participated in the second DARPA off-line intrusion detection evaluation in 1999. Three weeks of training and two weeks of test data were generated on a test bed that emulates a small government site. More than 200 instances of 58 attack types were launched against victim UNIX and Windows...
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The 1999 DARPA Off-Line Intrusion Detection Evaluation
October 1, 2000
Journal Article
Published in:
Comput. Networks, Vol. 34, No. 4, October 2000, pp. 579-595.
R&D area:
R&D group:
Summary
Eight sites participated in the second Defense Advanced Research Projects Agency (DARPA) off-line intrusion detection evaluation in 1999. A test bed generated live background traffic similar to that on a government site containing hundreds of users on thousands of hosts. More than 200 instances of 58 attack types were launched against victim UNIX and Windows NT hosts in three weeks of training data and two weeks of test data. False-alarm rates were low (less than 10 per day). The best detection was provided by network-based systems for old probe and old denial-of-service (DOS) attacks and by host-based systems for Solaris user-to-root (U2R) attacks. The best overall performance would have been provided by a combined system that used both host- and network-based intrusion detection. Detection accuracy was poor for previously unseen, new, stealthy and Windows NT attacks. Ten of the 58 attack types were completely missed by all systems. Systems missed attacks because signatures for old attacks did not generalize to new attacks, auditing was not available on all hosts, and protocols and TCP services were not analyzed at all or to the depth required. Promising capabilities were demonstrated by host-based systems, anomaly detection systems and a system that performs forensic analysis on file system data.
Summary
Eight sites participated in the second Defense Advanced Research Projects Agency (DARPA) off-line intrusion detection evaluation in 1999. A test bed generated live background traffic similar to that on a government site containing hundreds of users on thousands of hosts. More than 200 instances of 58 attack types were launched...
READ MORE