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Enhanced regional situational awareness

Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 355-380.

Summary

Airspace protection in the capital area is provided by an Integrated Air Defense System (IADS) created through the coordinated response of U.S. government and local law-enforcement agencies, including the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration, and the Capitol Police. The IADS includes U.S. Coast Guard helicopters, fighter aircraft, and airborne early-warning aircraft cued by surveillance radars. Under Operation Noble Eagle, the response to a threat includes warning flares deployed from fighter aircraft and, ultimately, the use of surface and air-launched missiles. Selecting the appropriate response requires a means for rapidly assessing the aircraft threat. New and existing sensors must be simultaneously cued to the target of interest and integrated with existing sources of information to display a common-air-picture display to support the decision makers. This article describes the development of an Enhanced Regional Situation Awareness system, an integrated sensing and decision support system developed for the complex and busy airspace surrounding the National Capital Region.
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Summary

Airspace protection in the capital area is provided by an Integrated Air Defense System (IADS) created through the coordinated response of U.S. government and local law-enforcement agencies, including the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration, and the Capitol Police. The IADS includes U.S. Coast...

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GPS-squitter automatic dependent surveillance broadcast: flight testing in the Gulf of Mexico

Published in:
Project Report ATC-235, MIT Lincoln Laboratory

Summary

During November - December 1994, MIT Lincoln Laboratory conducted a field evaluation of the air surveillance capabilities of GPS-Squitter in the Gulf of Mexico. Three squitter ground stations were located in the vicinity of Morgan City, Louisiana, for this evaluation: two were located on offshore oil platforms, and the third was located at an onshore heliport. Surveillance coverage tests were flown over the Gulf with three test aircraft - two helicopters and one Cessna 421 fixed wing aircraft. The helicopters flew at altitudes ranging from 100 to 2000 feet above sea level and the Cessna flew at 7500 and 20,000 feet. Extended squitter messages broadcast by each of the test aircraft provided aircraft position and identification. This report documents results of these texts and compares measured coverage to predicted coverage from the ground stations. Based on the good agreement between predicted and measured performance, a description of a possible operational system is included that would provide surveillance of the entire Gulf region serviced by oil platform helicopters. The report concludes that GPS Squitter is a near-term option for providing accurate, real time surveillance of aircraft operating in the offshore airspace in the Gulf of Mexico.
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Summary

During November - December 1994, MIT Lincoln Laboratory conducted a field evaluation of the air surveillance capabilities of GPS-Squitter in the Gulf of Mexico. Three squitter ground stations were located in the vicinity of Morgan City, Louisiana, for this evaluation: two were located on offshore oil platforms, and the third...

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GPS-squitter experimental results

Published in:
13th AIAA/IEEE Digital Avionics Systems Conf., 30 October - 3 November 1994, pp. 521-527.

Summary

GPS-Squitter is a system concept that merges the capabilities of Automatic Dependent Surveillance (ADS) and the Mode S beacon radar. The result is an integrated concept for seamless surveillance and data link that permits equipped aircraft to participate in ADS or beacon ground environments. This offers many possibilities for transition from beacon to ADS-based surveillance. This paper briefly defines the GPS-Squitter concept and its principal applications. The thrust of the paper is the presentation of surface and airborne surveillance measurements made at Hanscom Field in Bedford, Massachusetts and at the Logan International Airport in Boston. In each case the measurements show the excellent surveillance performance provided by this concept.
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Summary

GPS-Squitter is a system concept that merges the capabilities of Automatic Dependent Surveillance (ADS) and the Mode S beacon radar. The result is an integrated concept for seamless surveillance and data link that permits equipped aircraft to participate in ADS or beacon ground environments. This offers many possibilities for transition...

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Airport surface surveillance using differential GPS and the Mode S data link

Published in:
Proc. 50th Annual Mtg. of the Institute of Navigation, 6-8 June 1994, pp. 335-344.
Topic:

Summary

A new concept for providing surface surveillance of aircraft and ground vehicles has recently been tested at Hanscom Field in Bedford, Massachusetts. This concept, known as GPS-Squitter, combines the capabilities of differential GPS for navigation with those of the Mode S data link for communications. Together these systems provide accurate surveillance data along with a positive identification of surface traffic, both very important for an effective surface meillance system. The GPS-Squitter concept is based on the use of the Mode S squitter. The current squitter is a 56bit Mode S all-call reply message spontaneously broadcast by all aircraft Mode S transponders at a 1Hz rate. This message provides the unique Mode S address of an aircrsft and is used by TCAS (Traffic Alert and Collision Avoidance System) for acquisition of nearby aircraft. In the Hanscom testing, this squitter was extended to include GPS-based surveillance information. Two target vehicles participated in the experiments - one aircraft and one ground vehicle. They determined their position, heading, and speed using differential GPS and automatically broadcast that surveillance information to ground transmit/receive stations using the modified squitter. Differential GPS pseudorange and pseudorange rate corrections were formed by a reference station located at Hanscom Field and were transmitted by the ground transmit receive stations to the target vehicles. This paper describes the configuration of the target vehicles, the ground transmit/receive stations, and the differential GPS reference station. Results of the surface surveillance testing are provided including: system coverage, surveillance update rate, and differential GPS data quality. Ongoing testing at Logan International Airport is also discussed.
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Summary

A new concept for providing surface surveillance of aircraft and ground vehicles has recently been tested at Hanscom Field in Bedford, Massachusetts. This concept, known as GPS-Squitter, combines the capabilities of differential GPS for navigation with those of the Mode S data link for communications. Together these systems provide accurate...

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Demonstration of GPS Automatic Dependent Surveillance of aircraft using spontaneous Mode S broadcast messages

Published in:
Navig. J. Inst. Navig., Vol. 41, No. 2, Summer 1994, pp. 187-206.

Summary

A new Automatic Dependent Surveillance (ADS) system concept combining GPS-based positions with Mode S data communications is described. Several potential applications of this concept are presented with emphasis on surface surveillance at airports. The navigation and data link performance are analyzed. Compact ADS position formats are included. The results of the first tests at Hanscom Field, demonstrating the feasibility of the spontaneous broadcast of ADS positions using Mode S messages are presented. Test aircraft, vehicles, avionics equipment and the ground system configuration are described. Avionics standards and GPS interface requirements are discussed. Multipath and airport surface coverage issues are addressed. Further testing in an operational environment is continuing at Logan Airport.
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Summary

A new Automatic Dependent Surveillance (ADS) system concept combining GPS-based positions with Mode S data communications is described. Several potential applications of this concept are presented with emphasis on surface surveillance at airports. The navigation and data link performance are analyzed. Compact ADS position formats are included. The results of...

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Aircraft surveillance based on GPS position broadcasts from mode S beacon transponders

Published in:
Proc. of ION GPS, v 1, 1994, pp. 939-950.

Summary

Flight testing of a new air surveillance concept, GPS-Squitter, is reported. It integrates GPS receivers with the existing secondary surveillance radar beacon equipment carried by most aircraft. Simple, inexpensive, non-scanning ground stations listen for GPS position reports broadcast by the Mode S beacon transponders on the aircraft and send them on to air traffic control facilities. In addition to its surveillance application, GPS-Squitter presents opportunities for enhancing other important functions such as collision avoidance systems and data link services. System tradeoff studies are comparing range and altitude coverage with the cost and number of stations needed. Other issues are data link interference, multipath, total aircraft capacity, and unambiguous reporting range. The baseline system uses commercial off-the-shelf components such as TCAS (Traffic Alerting and Collision Avoidance System) avionics units, omni-directional DME (Distance Measuring Equipment) antennas, and computer workstations in order to ensure low production costs. The cost/performance tradeoff of minimum modifications such as the addition of a 6-sector antenna, multiple receive channels, or higher transmit power, are being evaluated. The omni-directional baseline system is designed for a range of 50 nmi while the 6-sector system is designed for 100 nmi range. Two aircraft have been equipped with Mode S beacon transponders modified to broadcast (i.e., "squitter") their GPS position twice each second. The numerous test flights have accumulated a significant data base including a demonstration of coverage out to over 100 nmi range. Data have been collected to analyze a number of issues: received power margins, performance of bottom versus top aircraft antenna, ground bounce multipath, propagation over water, and parallel runway approach monitoring. In addition, standard squitter data from commercial aircraft have been recorded and correlated with Mode S tracking to show link margins experienced in practice from aircraft in operational service. More tests are planned, including a demonstration of GPS-Squitter air surveillance in the Gulf of Mexico.
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Summary

Flight testing of a new air surveillance concept, GPS-Squitter, is reported. It integrates GPS receivers with the existing secondary surveillance radar beacon equipment carried by most aircraft. Simple, inexpensive, non-scanning ground stations listen for GPS position reports broadcast by the Mode S beacon transponders on the aircraft and send them...

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ADS-Mode S system overview

Published in:
AIAA/IEEE Digital Avionics Systems Conf., 25-28 October 1993, pp. 104-109.

Summary

ADS-Mode S is a system concept that merges the capabilities of Automatic Dependent Surveillance and the Mode S beacon radar. The result is an integrated system for seamless surveillance and data link that permits equipped aircraft to participate in ADS or beacon ground environments. This offers many possibilities for transitioning from a beacon to an ADS based surveillance system. The ADS-Mode S squitter. The current Mode S squitter is a spontaneous, periodic (once per second) 56-bit broadcast message containing the Mode S 24-bit address. This broadcast is provided by all Mode S transponders and is used by the Traffic Alert and Collision Avoidance System (TCAS) to acquire nearby Mode S equipped aircraft. For ADS-Mode S use, this squitter broadcast would be extended to 112 bits to provide for the transmission of a 56-bit ADS message field. The ADS squitter would be transmitted in addition to the current TCAS squitter in order to maintain compatibility with current TCAS equipment during transition.
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Summary

ADS-Mode S is a system concept that merges the capabilities of Automatic Dependent Surveillance and the Mode S beacon radar. The result is an integrated system for seamless surveillance and data link that permits equipped aircraft to participate in ADS or beacon ground environments. This offers many possibilities for transitioning...

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Demonstration of GPS automatic dependent surveillance of aircraft using spontaneous Mode S beacon reports

Published in:
Proc. ION-GPS-93 Sixth Int. Technical Mtg. of the Satellite Division of the Institute of Navigation, 22-24 September 1993, pp. 1-13.

Summary

A new Automatic Dependent Surveillance (ADS) system concept combining GPS satellite navigation with Mode S data communications is described. Several potential applications of this concept are presented with emphasis on surface surveillance at airports. The navigation and data link performance are analyzed. Compact ADS position formats are included. The results of the first tests at Hanscom Field demonstrating the feasibility of the spontaneous broadcast of ADS positions using Mode S messages are presented. Test aircraft, vehicles, avionics equipment and the ground system configuration are described. Avionics standards and GPS interface requirements are discussed. Multipath and airport surface coverage issues are addressed. Plans for further testing in an operational environment at Logan Airport are outlined.
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Summary

A new Automatic Dependent Surveillance (ADS) system concept combining GPS satellite navigation with Mode S data communications is described. Several potential applications of this concept are presented with emphasis on surface surveillance at airports. The navigation and data link performance are analyzed. Compact ADS position formats are included. The results...

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