MIT Reports to the President 1998-99

DIRECTOR, LINCOLN LABORATORY

Lincoln Laboratory is a mission-oriented laboratory operated by MIT for the Department of Defense (DoD) carrying out research and development in surveillance, identification, and communications. During the past year, agencies of the DoD–namely, the Air Force, the Army, the Navy, the Defense Advanced Research Projects Agency (DARPA), the Ballistic Missile Defense Office (BMDO), and the National Reconnaissance Office (NRO)–supplied approximately 84 percent of the Laboratory's budgetary support. The Federal Aviation Administration (FAA) provided most of the non-DoD support, which additionally includes work for the National Aeronautics and Space Administration (NASA) and the National Oceanographic and Atmospheric Agency (NOAA). Lincoln Laboratory also carries out pre-competitive research with industry under approved Cooperative Research and Development Agreements. For the federal fiscal year 1998, Lincoln Laboratory received $361 million, supporting the efforts of 1088 professional technical staff.

The following administrative changes occurred at the Laboratory Steering Committee level. Dr. Vincent Chan, Head of the Communications and Information Technology Division, became Co-Director of the Campus Laboratory for Information and Decision Systems, and Professor in the Department of Electrical Engineering and Computer Sciences and the Department of Aeronautics and Astronautics. Dr. Ed Taylor joined the Laboratory, replacing Prof. Chan as Head, and Dr. Kristin Rauschenbach was promoted to Associate Head of the Communications and Information Technology Division. Mr. David Martinez was promoted to Associate Head of the Air Defense Division. In a realignment of the Laboratory mission areas, Mr. Raymond LaFrey transferred to Associate Head of the Aerospace Division, Dr. Lewis Thurman transferred to Associate Head of the Tactical Systems Technology Division, and Dr. Eric Evans transferred to Associate Head of the Ballistic Missile Defense Technology Division.

Activity at the Laboratory focuses on DoD tasks in surveillance, identification, and communications technologies, supported by advanced electronic technology; on air traffic control technology for the FAA. Technical work areas include radar and optical sensors, measurements, and systems; communications; signal design and processing; identification algorithms; lasers; solid state devices; digital technology, circuitry, and data systems; and tactical control systems. Unclassified summaries of several accomplishments during the past year are presented below.

The Lincoln Near Earth Asteroid Research (LINEAR) project operates a wide-area asteroid search program employing an advanced electro-optic search system originally developed for the Air Force space surveillance applications. Recent advances in large-format, highly sensitive charged-coupled-device focal planes with fast readout rates, combined with customized data processing systems, allow the LINEAR project to search in excess of 10,000 square degrees per month to a limiting visual magnitude exceeding 19^th. During the period of March 1998 through June 1999, LINEAR searched 137,350 square degrees of sky and reported 1,125,488 observations to the Minor Planet Center at the Harvard-Smithsonian Astrophysical Observatory. The observations produced by LINEAR account for approximately 80 percent of the asteroid observations generated worldwide during this period. This effort resulted in discovery designations for 217 new NEOs (a total of 760 NEOs are now recorded by the Minor Planet Center), 27 new comets, and over 28,000 main-belt asteroids. These discoveries account for over 70 percent of the worldwide discoveries of both NEOs and main-belt asteroids during this period. These results were obtained with a 1-meter telescope at the Lincoln Laboratory Experimental Test Site in Socorro, NM.

Lincoln Laboratory is responsible for the design, development, and demonstration of the Advanced Land Imager (ALI) that will be launched on the National Aeronautics and Space Administration's (NASA) Earth Observing-1 mission. ALI is a land-imaging instrument that will demonstrate advanced technology to meet NASA's Mission to Planet Earth science needs in the 21^st century. The new technologies dramatically reduce the size, weight, and power of ALI versus the LANDSAT-7 Enhanced Thematic Mapper. Fabrication, calibration, and environmental testing of ALI have been completed and the instrument has been mounted on the spacecraft. Integrated system tests are in progress.

Sophisticated imaging sensors covering an increasing variety of spectral bands are being deployed. This creates a richness of exploitable features for remote target recognition and material determination but presents a challenge for data visualization. Lincoln Laboratory has pioneered the development of algorithmic techniques, based on analogies with the human visual system (HVS), for "fusing" such multi-sensor data so that it presents the appearance of naturally colored scenes to human viewers. This form of presentation to the human is a key enabler for a wide variety of advanced tactical and intelligence capabilities. In the last year, an HVS visualization system for real-time color night vision was successfully demonstrated in collaboration with the United States Special Operations Command. An HVS system for visualizing multi-sensor intelligence imagery was successfully demonstrated onboard the USS Coronado as part of the Marines' Urban Warrior exercises in San Francisco Bay. Future HVS development will include refinement of capabilities for a wider user base, and incorporation of non-imaging data such as ground-moving-target-indicator radar data and signal-intercept detections.

Lincoln Laboratory is into the second year of a hyperspectral technology assessment program that will lay out the framework needed to characterize the potential value of hyperspectral imaging (HSI) systems with hundreds of optical bands to DoD operations, and will apply this framework to identify opportunities for near-term technology development and demonstration. The general objective of this effort is to establish a quantitative baseline that accurately characterizes the status of HSI, and to develop methodologies and tools for continued assessment and improvement of HSI systems by the DoD. During the first year, three specific application areas were pursued: (1) background classification, (2) target detection and identification, and (3) atmospheric characterization. Concurrently, the development of a system performance model was conducted to include a comprehensive combination of sensor specifications, scene statistics, and processing algorithms.

Since the end of the Cold War and dissolution of the Soviet Union, the missile data collection effort has focused on the Theater Ballistic Missile systems of rest-of-world (ROW) countries. A key and consistent recommendation of studies addressing the ROW missile threat is the need to provide a low-cost, air- and ground-transportable, radar system to collect data on ROW missiles. Lincoln Laboratory has developed the prototype of such a concept: the COBRA GEMINI radar system. COBRA GEMINI operates at both S- and X-band frequencies and has wideband imaging capability. The system which uses a novel open-system architecture has completed land- and sea-based test and evaluation and has been declared operational.

The DoD is currently embarked upon a program to develop and make preparations to deploy a system to defend the United States against a limited ballistic missile attack by a rogue country. Lincoln Laboratory is supporting the National Missile Defense (NMD) program at both the system and element levels. System work focuses on evaluating discrimination architectures against postulated and potential threats. Element support emphasizes characterization and assessment of early warning radar, prototype ground based radar, and exoatmospheric kill vehicle seeker performance, primarily through design and analysis of flight tests.

The Theater High-Altitude Area Defense (THAAD) system is currently undergoing demonstration/validation flight testing at White Sands Missile Range. The system is designed to provide large-area defense against theater ballistic missiles. Lincoln Laboratory provides detailed characterization of the radar's performance. In addition, the Laboratory conducts testing and analysis of the baseline decision algorithms, as well as continuous development and transfer of discrimination algorithm upgrades for the THAAD radar.

Over the past several years Lincoln Laboratory and the Advanced Electronic Guidance and Instrumentation System (AEGIS) program office have been supporting the development of a theater ballistic missile defense (TBMD) capability. This capability is separated into two programs: a Navy area system (lower tier) and a Navy theater-wide (NTW) system (upper tier), and differs greatly from the current anti-aircraft warfare capability.

The challenges associated with detection, discrimination, and handover of hostile targets within a TBMD complex have been an area of active Laboratory work, including algorithms for synthetic wideband radar measurements and algorithms to improve IR focal-plane performance, which includes the use of a two-color focal plane. These issues are particularly challenging for the NTW system performing discrimination in the exoatmosphere.

The Theater Missile Defense (TMD) Critical Measurements Program (TCMP) employs a sequence of flight tests executed at Kwajalein Missile Range to provide IR and radar measurements that address critical TMD system-level issues. Lincoln Laboratory supports TCMP in four task areas: (1) mission planning and integration, (2) payload development, (3) flyaway IR sensor development, and (4) data analysis. The first flight of the third campaign (TCMP-3) is scheduled for September 1999.

The capabilities of modern air defense missile systems have been severely challenged by the advent of low-observable vehicles and modern electronic countermeasures. The Airborne Seeker Test Bed (ASTB) is an instrumentation platform developed by Lincoln Laboratory to investigate these challenges and identify appropriate seeker architectures and signal processing algorithms for dealing with them.

The ASTB is based in a Gulfstream II aircraft and provides high-fidelity RF and IR reference instrumentation sensors that are used in parallel with special-purpose wing-pod payloads carrying production seekers or sensors under test. The combination of the system under test with the instrumentation sensors yields insight into the performance of sensor systems and advanced signal processing algorithms.

One of the principle sensors in use during the last year was the RF seeker pod (first flown in 1997). A control architecture was implemented for the RF seeker pod so that its actions can be controlled by a ground-based radar. This allowed flight testing of target intercepts where the tracking radar and the seeker share data and act as an integrated system. Extensive tests were conducted in Nevada to evaluate the performance of a variety of electronic countermeasure techniques against this radar/seeker system, in an effort to develop effective countermeasures. Flight testing with the IR seekers carried on the ASTB focused on evaluating the effects of background clutter on the detection and tracking of target aircraft. Two new RF seekers with different designs have been received, and each will be integrated into a flight test configuration during the next year.

The laboratory is nearing completion of an airborne space-time adaptive processing (stap) testbed to demonstrate enhanced target detections in the presence of severe clutter and jamming interference. The real time demonstration demands a high-performance computer with a capability approaching 185 billion operations per second (gops). The signal processor divides into two main processing subsystems: the front-end processor (fep) and the programmable signal processor (psp). The fep is a custom hardware subsystem that delivers 100 gops of throughput and performs digital in-phase and quadrature filtering. The output of the fep is sent to the psp, a commercial-off-the-shelf (cots) massively parallel processor.

The PSP contains nearly 1000 processors and is rated at 85 billion floating-point operations per second (GFLOPS) peak throughput. One of the major tasks undertaken by the Laboratory has been the programming of the PSP to perform real-time digital filtering, space-time-adaptive processing, target detection, and target parameter estimation. This has required the development of approximately 160,000 source lines of code that implement the parallel signal processing algorithms.

The modern battlefield requires that airborne early-warning surveillance platforms, such as the navy's e-2c, detect small targets in the presence of severe jamming and sea/land clutter. Adaptive signal processing techniques, such as space-time adaptive processing (stap), enable enhanced target-detection capability in the presence of clutter and jamming. These techniques use multiple receive antenna channels and digital signal processing algorithms to shape the receive beam pattern in the spatial and doppler domains.

Although the current e-2c radar has two receive channels, a significantly higher number of receive channels are required for stap processing. To meet this challenge, lincoln laboratory developed a full custom cmos vlsi signal processor was developed by using a very high-performance scalable bit-level systolic cell library. Each chip functions as a massively parallel signal processor and consists of tens of thousands of one-bit processors. Using massively parallel signal processing, each chip can perform up to 23 billion operations per second. The resulting multichip-module (mcm)-based receiver/processor includes 32 receive channels, is approximately 3.5" x 5" x 0.5", and performs approximately 60 billion operations per second. The receiver and analog-to-digital mcms have been tested together and show excellent performance characteristics, including low noise figure and high dynamic range. The 60-gops vlsi signal processor mcm is currently being tested, and initial test results are very positive.

Under the Next Generation Internet (NGI) initiative, DARPA sponsored a new consortium to explore the application of wavelength division multiplex (WDM) all optical network (AON) technology into access networks. In addition to both MIT Campus and Lincoln Laboratory researchers, the consortium includes as members an Internet and local service provider, enterprise and backbone internet router manufacturers, and a WDM component supplier. The consortium team is exploring architecture, algorithms, and technology that promise orders of magnitude increase in the end-user bandwidth available for the NGI. The consortium has started rollout of a Boston-area testbed to validate this novel architecture and associated hardware and software. The testbed will connect to the national-scale DARPA-sponsored Supernet to spark future applications that can harness the tremendous power of this new access network technology.

During this year, the development of concepts and technologies for extending networks over military communications satellites has continued. This work has included an architecture for an intersystem connectivity node that interfaces remotely deployed military users of the Milstar communications satellite system to other satellite or terrestrial communications systems for secure voice and video teleconferencing as well as data services (such as the Internet and similar classified networks). In addition, protocols for highly efficient transfer of bursty data traffic over satellites have been developed. System access and traffic security issues are also being addressed.

Lincoln Laboratory's extensive protected communications satellite testbeds have become national-level test and training facilities. The requests for their use increased significantly following the recent Milstar satellite launch failure. The Laboratory's Milstar payload simulator has been used by the Army for terminal evaluation and user training at three bases (Ft. Gordon, Ft. Monmouth, and Ft. Hood). In addition, a Lincoln Laboratory developed test terminal is being used by the Air Force in the Milstar satellite factory for payload functionality testing.

To allow broader use of protected satellite communications systems, the Laboratory completed a 12 lbs. Milstar Satcom terminal which incorporates a web server interface that is network addressable, support multiple users, and permits implementation of router functionality. This interface also provides embedded terminal control to accommodate heterogeneous input/output devices and provides server capabilities for gateway-like service. The terminal effort now focuses on the design of a similarly small-sized terminal that will provide much higher data rate (~100 kbps) services by implementing a more flexible (reprogrammable) and capable digital processing system. Algorithms are being developed so that on-the-move communications can also be provided from the same basic terminal design.

At speed and depth submarines can currently receive only several bits per second (bps). Lincoln Laboratory has developed a buoyant cable array system that is expected to provide approximately 24 kbps for 2-way global satcom coverage. The near-term focus is on UHF Fleetsat communications along with L-band Iridium voice and the Global Positioning System. The most significant challenge is to mitigate the effects of water washing over the antenna elements. A linear array of discrete floating antenna elements on the surface of the ocean that both transmits to and receives signals from the satellite has been developed. The array is flexible and conforms to the ocean surface. With the antenna in this dynamic environment, the key is to apply adaptive processing techniques to form the beam using only those elements that are out of the water. This signal is then passed into a modem for normal communication.

These concepts were demonstrated during 1998 and 1999 by using Fleetsat in Massachusetts Bay and off the coast of Kauai, Hawaii. A data rate of 40 kbps in Sea State 3 with a zero bit error rate was achieved with a standard QPSK waveform.

Lincoln Laboratory has developed a new approach for passive sonar spectral filtering, background estimation, and noise equalization called the Full Spectrum Normalizer (FSN). This algorithm enhances the contrast between target signatures and background noise on the displays that sonar analysts use to detect other submarines. The FSN algorithm has transitioned to both submarine and surveillance sonar systems and will be evaluated at sea early next year. Efforts are continuing to expand the FSN methodology to include multidimensional processing across time, frequency, and bearing.

In order to enhance communications among multinational forces in a coalition environment, Lincoln Laboratory has been working on a computer-automated translation system, with focus on English/Korean translation for US/Republic of Korea Combined Forces Command. During the April 1999 reception, staging, onward movement and integration exercise, the Lincoln Laboratory system was installed on the communications network at the theater Tactical Operations Center in Seoul, Korea, and was used successfully for English-to-Korean translation of operational commander's briefing slides. After this exercise, the translation system remained in Korea for ongoing integration, test, and operational experimentation.

Lincoln Laboratory has a number of programs to assure the security of the United States' increasingly vulnerable and interconnected infrastructures. The Laboratory coordinated for DARPA the first-ever quantitative evaluation of computer network intrusion detection system accuracy. Six sites participated in this evaluation. A significant outcome of this evaluation was that next-generation systems have lower false-alarm rates than systems currently deployed by the government, but detection of novel attacks is a problem even for next-generation systems. Bottleneck verification, a particular type of next-generation intrusion detection system developed at Lincoln Laboratory, is being deployed for prototype operational use at a local Air Force base. If those tests are successful, bottleneck verification could be deployed to protect a wide range of military bases. The Laboratory is studying the extent to which today's intrusion-detection products can be applied to non-standard networks such as those found in FAA en route centers and on Army battlefields.

Lincoln Laboratory is working with the FAA and NASA to enhance air safety, reduce controller workload, and increase airport capacity by developing planning aids for air traffic controllers. A new effort to develop algorithms that dynamically adapt air traffic control sectors to changing conditions, such as the passage of line storms, has begun. This activity will take advantage of new weather-forecast products developed in the Integrated Terminal Weather System (ITWS) program to adjust sector boundaries to minimize delay and avoid high work-load traffic concentrations.

Additional work sponsored by NASA Ames is being carried out to integrate advanced weather products developed by Lincoln Laboratory into the Center Terminal Automation System (CTAS) developed by NASA. The CTAS helps coordinate activities between arrival controllers located at en route centers and final-approach controllers located at radar control facilities. The focus of initial work is on integrating wind field products from the ITWS in order to improve aircraft trajectory estimates. Concept exploration work is also underway on the use of ITWS convective weather products in CTAS for determining weather-impacted routes.

The FAA airport surveillance radar deployed at major terminal areas, the ASR-9, uses computer-processing technology dating to the early 1980s. Hardware and software limitations prohibit the installation of needed improvements and upgrades. In 1993, Lincoln Laboratory initiated a program to design and program a single plug-in card (the ASR-9 Processor Augmentation Card) to replace the radar data processor. This card offers ten times the processing power and improved software maintainability and upgradability. Following intensive FAA testing in 1995, prototype cards were installed in commissioned FAA air traffic control radars located at airports in Los Angeles, Dallas-Fort Worth, Oakland, and Honolulu. Production cards from industry are now being installed in all 140 operational ASR-9s.

Lincoln Laboratory continues to support the refinement of the wind-shear detection algorithms utilized in the Laboratory-designed Terminal Doppler Weather Radar (TDWR) now deployed at many major airports. An adaptation of the TDWR algorithms together with innovative techniques for estimating low-altitude wind shear with fan beam radars has enabled the FAA Airport Surveillance Radars (ASR) to be equipped with a weather systems processor that will provide wind-shear warning and storm motion capability at the nation's medium-density airports. The Laboratory is playing a major role in development of production versions of the ASR9 weather systems processor while continuing to operate a testbed system at Albuquerque, NM, and recently, at Austin, TX. Work also commenced on improving the weather-detection capability of the FAA's newest surveillance radar, the ASR11.

The Laboratory-developed Integrated Terminal Weather System (ITWS) will significantly extend the TDWR capability in the areas of hazardous airspace identification, winds to support automation systems, and the short-term forecasts of significant weather. The Laboratory is transitioning the Laboratory-developed algorithms for generating the ITWS products to the FAA's full-scale development contractor. It is expected that production versions of ITWS will be installed at major airports starting in 2001. The Laboratory has continued to operate ITWS testbeds in Memphis, TN; Orlando, FL; Dallas-Ft. Worth, TX; and New York City airports (funded by the Port Authority of New York and New Jersey) to increase the ITWS data base and test enhanced products such as those which predict convective storm growth and decay. An additional experimental site in San Francisco, CA, supports the development of ceiling and visibility products.

A program is underway at the Laboratory to develop a system to safely reduce aircraft separations on approach and departure. Extensive measurements of wake vortices and the boundary-layer weather conditions were carried out at the Dallas-Ft. Worth international airport to validate and extend models for predicting wake-vortex behavior. The development of a low-cost pulsed laser radar for wake-vortex detection and tracking has been initiated.

Photolithography using 157-nm lasers has recently emerged, as the technology preferred by the semiconductor industry for printing transistor circuits at dimensions of 70 to 100 nm, expected to be in production in 2004 through 2007. This development is largely due to work performed at Lincoln Laboratory, which included the first 70-nm patterning, and demonstration of transmissive lens materials and photomask materials at 157 nm. The Laboratory is currently engaged in developing photoresists, testing optical materials and coatings, and studying the effects of ambient-induced contamination of optical surfaces. The Laboratory is the focus of several cooperative activities with semiconductor manufacturers and suppliers, and is driving the development of lithographic tools at 157 nm, as it has previously done at 193 nm.

Optical techniques have been successfully applied to performing precision measurements of electrical signals. Short optical pulses with low timing jitter from a mode-locked laser are used to sample microwave signals in an electro-optic modulator. Optical demultiplexing in a bank of modulators then distributes the sampled wideband signal into many photodiodes and semiconducting quantizers. Lincoln Laboratory has demonstrated 10 bits of measurement resolution at 200 Msps with third-order intermodulation distortion less than -80 dBc. The short sampling pulses have allowed measurements at 3 GHz, directly down-sampling the RF to baseband.

Lincoln Laboratory demonstrated a receiver that detects, in 100 nanoseconds, multiple radar emitters anywhere in the 4-GHz frequency range of X-band. High-temperature-superconductor materials, combined with high-speed analog-to-digital conversion and advanced digital signal processing could reduce weight and power consumption by a factor of 5 to 10. A 3-GHz version of this radar-intercept receiver was launched in February 1999 onboard the USAF Argos experimental satellite. Tests of this space-borne receiver and other superconductive subsystems are now being carried out by the Naval Research Laboratory as part of the High-Temperature-Superconductor Space Experiment.

Lincoln Laboratory low-power correlator chips developed for NASA are currently providing the International Space Station with all data, voice, and video communications to the ground. The transceiver, which sends spread-spectrum signals via NASA's Tracking and Data Relay Satellite, was obtained from industry. The correlators were supplied to industry from NASA as government-furnished equipment. Lincoln Laboratory achieved the low-power signal processing by combining analog charge-coupled devices (CCDs) with complementary metal-oxide-silicon (CMOS) digital circuits. The CCD/CMOS chip produces 512 simultaneous 8-bit-x-1-bit correlations at 40 MHz at less than 1 W of power.

Proof-of-principle demonstrations of a novel technique for beam-combining laser arrays have been accomplished. This should enable the outputs of hundreds of lasers to be combined into a single laser beam, thereby enabling efficient high-power laser sources with the advantages of reliable and compact solid state construction. The beam-combining technique relies on the principle of having each laser of the array operate at a slightly different wavelength. Initial demonstrations combined the outputs from two ytterbium-doped fiber lasers in one example and the outputs from 11 semiconductor lasers in another example.

Lincoln Laboratory developed the CCD imagers and packaging technology for one of the two sensors on the NASA Chandra X-ray Observatory. The X-ray-sensitive imaging array was developed and fabricated at Lincoln Laboratory over a period of five years. The MIT Center for Space Research integrated the array into the advanced X-ray astrophysics imaging spectrometer instrument, and this entire package was furnished to NASA.

Lincoln Laboratory's Microelectronics Laboratory fabricates fully depleted silicon on insulator CMOS integrated circuits for high-speed, low-power applications. For example, an integrated circuit described last year is now functioning normally in NASA's Deep Space 1 vehicle launched in October 1998 and currently 16 million from earth. Chips designed by the Mayo Foundation and fabricated at Lincoln Laboratory demonstrate speeds up to 3.9 GHz with only a 2-V power supply and power as low as 0.055 m W/MHz/gate. This silicon technology has cost and power advantages over gallium-arsenide technology.

David L. Briggs

MIT Reports to the President 1998-99