Publications
Design and testing of an all-digital readout integrated circuit for infrared focal plane arrays
August 3, 2005
Conference Paper
Published in:
SPIE Vol. 5902. Focal Plane Arrays for Space Telescopes II, 3-4 August 2005, pp. 1-11.
Summary
The digital focal plane array (DFPA) project demonstrates the enabling technologies necessary to build readout integrated circuits for very large infrared focal plane arrays (IR FPAs). Large and fast FPAs are needed for a new class of spectrally diverse sensors. Because of the requirement for high-resolution (low noise) sampling, and because of the sample rate needed for rapid acquisition of high-resolution spectra, it is highly desirable to perform analog-to-digital (A/D) conversion right at the pixel level. A dedicated A/D converter located under every pixel in a one-million-plus element array, and all-digital readout integrated circuits will enable multi- and hyper-spectral imaging systems with unprecedented spatial and spectral resolution and wide area coverage. DFPAs provide similar benefits to standard IR imaging systems as well. We have addressed the key enabling technologies for realizing the DFPA architecture in this work. Our effort concentrated on demonstrating a 60-micron footprint, 14-bit A/D converter and 2.5 Gbps, 16:1 digital multiplexer, the most basic components of the sensor. The silicon test chip was fabricated in a 0.18- micron CMOS process, and was designed to operate with HgxCd1-xTe detectors at cryogenic temperatures. Two A/D designs, one using static logic and one using dynamic logic, were built and tested for performance and power dissipation. Structures for evaluating the bit-error-rate of the multiplexer on-chip and through a differential output driver were implemented for a complete performance assessment. A unique IC probe card with fixtures to mount into an evacuated, closed-cycle helium dewar were also designed for testing up to 2.5 Gbps at temperatures as low as 50 K.
Summary
The digital focal plane array (DFPA) project demonstrates the enabling technologies necessary to build readout integrated circuits for very large infrared focal plane arrays (IR FPAs). Large and fast FPAs are needed for a new class of spectrally diverse sensors. Because of the requirement for high-resolution (low noise) sampling, and...
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Description of the Corridor Integrated Weather System (CIWS) weather products
August 1, 2005
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-317
Summary
Improved handling of severe en route and terminal convective weather has been identified by the FAA in both the Operational Evolution Plan (OEP) (FAA, 2002) and the Flight Plan for 2004-2008 (FAA, 2003) as a major thrust over the coming decade for the National Airspace System (NAS) modernization. Achieving such improved capabilities is particularly important in highly congested corridors where there is both a high density of over flights and major terminals. Delay increases during thunderstorm season have been the principal cause of the dramatic delay growth in the US aviation system. When major terminals also underlie the en route airspace, convective weather has even greater adverse impacts, especially if the convective weather occurs frequently. In response to the need to enhance both safety and capacity during adverse weather, the FAA is exploring the concept of a Corridor Integrated Weather System (CIWS). CIWS is designed to improve convective weather decision support for congested en route airspace (and the terminals that lie under that airspace) by automatically generating graphical depictions of the current severe weather situation and providing frequently updated forecasts of the future weather locations for forecast times from zero to two hours. An operational demonstration of the CIWS was conducted during the summer of 2003. This document provides a detailed description of each CIWS weather information product as it was demonstrated in 2003, including a general description of the product, what data sources are used by the product, how the product is generated from the input data, and what caveats in the technical performance apply. A discussion of how the products might be used to enhance safety and support decision-making for traffic management is also included. Detailed information on the operational benefits of the CIWS products demonstrated in 2003 is provided in a companion report (Robinson et al., 2004). Improvements made to the products for the 2004 and 2005 CIWS operational demonstrations are briefly discussed in the final chapter.
Summary
Improved handling of severe en route and terminal convective weather has been identified by the FAA in both the Operational Evolution Plan (OEP) (FAA, 2002) and the Flight Plan for 2004-2008 (FAA, 2003) as a major thrust over the coming decade for the National Airspace System (NAS) modernization. Achieving such...
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A wide area network simulation of single-round group membership algorithms
July 27, 2005
Conference Paper
Published in:
NCA 2005: 4th IEEE Int. Symp. on Network Computing and Applications, 27-29 July 2005, pp. 159-168.
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Summary
A recent theoretical result proposed Sigma, a novel GM protocol that forms views using a single-round of message exchange. Prior GM protocols have required more rounds in the worst-case. In this paper, we investigate how well Sigma performs in practice. We simulate Sigma using WAN connectivity traces and compare its performance to two leading GM protocols, Moshe and Ensemble. Our simulations show, consistently with theoretical results, that Sigma always terminates within one round of message exchange, faster than Moshe and Ensemble. Moreover, Sigma has less message overhead and produces virtually the same quality of views. We also observe that view-oriented GM in dynamic WAN-like environments is practical only in applications where GM need not respond to every disconnect immediately when detected. These applications are able, and prefer, to delay GM response and ignore transient disconnects, avoiding frequent futile view changes and associated overhead. We reference some applications in this category.
Summary
A recent theoretical result proposed Sigma, a novel GM protocol that forms views using a single-round of message exchange. Prior GM protocols have required more rounds in the worst-case. In this paper, we investigate how well Sigma performs in practice. We simulate Sigma using WAN connectivity traces and compare its...
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Operational benefits of the Integrated Terminal Weather System (ITWS) at Atlanta
July 15, 2005
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-320
Summary
This report summarizes the results of an initial study to estimate the yearly delay reduction provided by the initial operational capability (IOC) Integrated Terminal Weather System (ITWS) at Hartsfield-Jackson Atlanta International Airport (ATL). Specific objectives of this initial study were to: (1) analyze convective weather operations at ATL to determine major causes of convective weather delay and how those might be modeled quantitatively. (2) provide estimates of the ATL ITWS delay reduction based on the "Decision/Modeling" method using questionnaires and interviews with Atlanta Terminal Radar Approach Control (TRACON) and Air Route Traffic Control Center (ARTCC) operational ITWS users. (3)assess the "reasonableness" of the model-based delay reduction estimates by comparing those savings with estimates of the actual weather-related arrival delays at ATL. In addition, the reasonableness of model-based delay reduction estimates was assessed by determining the average delay savings per ATL flight during times when adverse convective weather is within the coverage of the ATL ITWS. (4)conduct an exploratory study confirming the ATL ITWS delay savings by comparing Aviation System Performance Metrics (ASPM) database delays pre- and post-ITWS at ATL. (5) assess the accuracy of the "downstream" delay model employed in this study by analyzing ASPM data from a major US airline, and (6) make recommendations for follow-on studies of the ITWS delay reduction at Atlanta and other IOC ITWS facilities. [not complete]
Summary
This report summarizes the results of an initial study to estimate the yearly delay reduction provided by the initial operational capability (IOC) Integrated Terminal Weather System (ITWS) at Hartsfield-Jackson Atlanta International Airport (ATL). Specific objectives of this initial study were to: (1) analyze convective weather operations at ATL to determine...
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Enhanced detection and classification of buried mines with an UWB multistatic GPR
July 3, 2005
Conference Paper
Published in:
IEEE Antennas and Propagation Society Int. Symp. 2005 Digest, Vol. 3B, 3-8 July 2005, pp. 88-91.
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Summary
In this paper we present a resonance-based classification technique for the identification of plastic-cased antipersonnel (AP) land mines buried in lossy and dispersive soils under rough surfaces by a stepped-frequency ultra-wideband (UWB) downward-looking ground penetrating radar (GPR) with an array of receivers. For this application the multistatic ground probing sensor is positioned just above the ground surface and operates from UHF to C-Band frequencies. Novel physics-based models based on the finite difference frequency domain (FDFD) technique simulate the characteristic resonating multi-aspect target frequency responses for several realistic buried land mine detection scenarios. Matched filter detection results are presented which assess the GPR's performance in identifying a simulated mine buried under a rough surface at varying depths in dry sand and a dispersive clay loam soil from other false targets such as buried rocks.
Summary
In this paper we present a resonance-based classification technique for the identification of plastic-cased antipersonnel (AP) land mines buried in lossy and dispersive soils under rough surfaces by a stepped-frequency ultra-wideband (UWB) downward-looking ground penetrating radar (GPR) with an array of receivers. For this application the multistatic ground probing sensor...
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Quantifying convective delay reduction benefits for weather/ATM systems
June 27, 2005
Conference Paper
Published in:
USA/Europe Air Traffic Management Seminar, 27-30 June 2005.
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Summary
This paper investigates methods for quantifying convective weather delay reduction benefits for weather/ATM systems and recommends approaches for future assessments. This topic is particularly important at this time because: 1. Convective weather delays continue to be a dominant factor in the overall National Airspace System (NAS) delays, and 2. Benefits quantification and NAS performance assessment have become very important in an era of significant government and airline budget constraints for civil aviation investments. Quantifying convective weather delay benefits for ATM systems has proven to be quite difficult since the delays arise from complicated, highly variable, poorly understood interactions between convective weather and a very complex aviation system. In this paper, we consider key aspects of convective weather disruptions of the aviation system, how the weather severity can be characterized, and discuss practical experience with benefits quantification by a variety of approaches. The paper concludes with recommendations for a methodology to be used in future convective weather delay reduction quantification studies.
Summary
This paper investigates methods for quantifying convective weather delay reduction benefits for weather/ATM systems and recommends approaches for future assessments. This topic is particularly important at this time because: 1. Convective weather delays continue to be a dominant factor in the overall National Airspace System (NAS) delays, and 2. Benefits...
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Safety analysis methodology for unmanned aerial vehicle (UAV) collision avoidance systems
June 27, 2005
Conference Paper
Published in:
USA/Europe Air Traffic Management Seminar, 27-30 June 2005.
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Summary
The integration of Unmanned Aerial Vehicles (UAVs) into civil airspace requires new methods of ensuring collision avoidance. Concerns over command and control latency, vehicle performance, reliability of autonomous functions, and interoperability of sense-and-avoid systems with the Traffic Alert and Collision Avoidance System (TCAS) and Air Traffic Control must be resolved. This paper describes the safety evaluation process that the international community has deemed necessary to certify such systems. The process focuses on a statistically-valid estimate of collision avoidance performance developed through a combination of airspace encounter modeling, fast-time simulation of the collision avoidance system across millions of encounter scenarios, and system failure and event sensitivity analysis. Example simulation results are provided for an implementation of the analysis process currently being used to evaluate TCAS on the Global Hawk UAV.
Summary
The integration of Unmanned Aerial Vehicles (UAVs) into civil airspace requires new methods of ensuring collision avoidance. Concerns over command and control latency, vehicle performance, reliability of autonomous functions, and interoperability of sense-and-avoid systems with the Traffic Alert and Collision Avoidance System (TCAS) and Air Traffic Control must be resolved...
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Safety analysis for advanced separation concepts
June 27, 2005
Conference Paper
Published in:
USA/Europe Air Traffic Management Seminar, 27-30 June 2005.
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Summary
Aviation planners have called for increasing the capacity of the air transportation system by factors of two or three over the next 20 years. The inherent spatial capacity of en route airspace appears able to accommodate such traffic densities. But controller workload presents a formidable obstacle to achieving such goals. New approaches to providing separation assurance are being investigated to overcome workload limitations and allow airspace capacity to be fully utilized. One approach is to employ computer automation as the basis for separation-assurance task. This would permit traffic densities that exceed the level at which human cognition and decision-making can assure separation. One of the challenges that must be faced involves the ability of such highly automated systems to maintain safety in the presence of inevitable subsystem faults, including the complete failure of the supporting computer system. Traffic density and flow complexity will make it impossible for human service providers to safely reinitiate manual control in the event of computer failure, so the automated system must have inherent fail-soft features. This paper presents a preliminary analysis of the ability of a highly automated separation assurance system to tolerate general types of faults such as nonconformance and computer outages. Safety-related design features are defined using the Advanced Airspace Concept (AAC) as the base architecture. Special attention is given to the impact of a severe failure in which all computer support is terminated within a defined region. The growth and decay of risk during an outage is evaluated using fault tree methods that integrate risk over time. It is shown that when a conflict free plan covers the region of the outage, this plan can be used to safely transition aircraft to regions where service can still be provided.
Summary
Aviation planners have called for increasing the capacity of the air transportation system by factors of two or three over the next 20 years. The inherent spatial capacity of en route airspace appears able to accommodate such traffic densities. But controller workload presents a formidable obstacle to achieving such goals...
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Megapixel CMOS image sensor fabricated in three-dimensional integrated circuit technology
June 19, 2005
Conference Paper
Published in:
2005 IEEE Int. Solid-Stat Circuits Conf. Digest of Technical Papers, Pt.1, 19-25 June 2005, p. 356-357.
Summary
In this paper a 3D integrated 1024x1024, 8um pixel visible image sensor fabricated with oxide-to-oxide wafer bonding and 2-um square 3-D-vias in every pixel is presented. The 150mm wafer technology integrates a low-leakage, deep-depletion, 100% fill factor photodiode layer to a 3.3-V, 0.35-um gate length fully depleted (FD) SOI CMOS readout circuit layer.
Summary
In this paper a 3D integrated 1024x1024, 8um pixel visible image sensor fabricated with oxide-to-oxide wafer bonding and 2-um square 3-D-vias in every pixel is presented. The 150mm wafer technology integrates a low-leakage, deep-depletion, 100% fill factor photodiode layer to a 3.3-V, 0.35-um gate length fully depleted (FD) SOI CMOS...
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Polymorphous computing architecture (PCA) kernel-level benchmarks [revision 1]
June 13, 2005
Project Report
Published in:
MIT Lincoln Laboratory Report PCA-KERNEL-1,REV.1
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Summary
This document describes a series of kernel benchmarks for the PCA program. Each kernel benchmark is an operation of importance to DoD sensor applications making use of a PCA architecture. Many of these operations are a part of the composite example applications described elsewhere. The kernel-level benchmarks have been chosen to stress both computation and communication aspects of the architecture. "Computation" aspects include floating-point and integer performance, as well as the memory hierarchy, while the "communication" aspects include the network, the memory hierarchy, and the I/O capabilities. The particular benchmarks chosen are based on the frequency of their use in current and future applications. They are drawn from the areas of signal processing, communication, and information and knowledge processing. The specification of the benchmarks in this document is meant to be high-level and largely independent of the implementation.
Summary
This document describes a series of kernel benchmarks for the PCA program. Each kernel benchmark is an operation of importance to DoD sensor applications making use of a PCA architecture. Many of these operations are a part of the composite example applications described elsewhere. The kernel-level benchmarks have been chosen...
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