Space, Telecommunications and Radioscience Laboratory (STARLab)

From Stanford Electrical Engineering Department Graduate Handbook

www-star.stanford.edu/

Umran Inan, Director, Packard 355, (650)723-4994, inan at nova.stanford.edu

Shaolan Min, Administrative Associate, Packard 356, (650)723-7712, shaolan at nova.stanford.edu

Research areas in the STAR Laboratory share a common basis in the study and exploitation of electromagnetic wave phenomena. The laboratory makes use of electromagnetic waves to probe remote environments as well as in the development of communications systems.

Several members of the laboratory are active in the Center for Telecommunications. Work in the telecommunications area includes space, mobile radio, and optical fiber communication systems. Digital switching and signal processing studies, together with VLSI implementation, are an important part of these activities. Faculty and students also participate with others in the School of Engineering in the research of the NASA/Stanford Center for Aeronautics and Space Information Systems (CASIS).

STARLab research in wireless personal communications systems encompasses cellular mobile radio, high speed wireless data networks, and low-power personal communications systems and includes:

1. pattern classification and recognition techniques applied to signal measurements to improve the accuracy of channel assignment and handoff in multipath;
2. analysis and synthesis of multi-frequency, delay-spread equalization, interference cancellation architectures, and algorithms for improving the performance of new wireless data and personal communications systems;
3. determination of functions required in large networks to support nomadic mobile users and the additional processing load required to manage mobility;
4. synthesis and analysis of interference cancellation, multipath delay-spread equalization, and other signal processing architectures that minimize power consumption while providing good system performance; and
5. construction of models of multipath propagation and shadowing for analyzing performance of wireless systems.

Optical fiber research in STARLab focuses on experimental and theoretical research in advanced optical fiber communications. The emphasis is on components development, systems and networks. Current efforts include:

1. contention resolution using switched delay lines for high speed ATM networks aimed at demonstrating a novel optoelectronic node front end consisting of optical delay lines and fast optical switches;
2. STARNET, a high-speed wavelength-division multiplexing optical network to provide a 125 Mb/s packet switched subnetwork and a 2.5 Gb/s/node circuit switched subnetwork simultaneously;
3. analog optical links, with focus on improving system performance by the use of coherent detection and optical amplifiers; and
4. understanding fiber nonlinearities in high-power and multi-channel optical systems.

STARLab research in electromagnetics and remote sensing comprises a variety of activities for learning about the natural environment. Measurements using radio signals traveling between the ground and NASA planetary spacecraft are used to study planetary atmospheres, ionospheres, and planetary ring systems. Such measurements represent an important, precise source of information on these objects. Carom signals traveling between orbiting spacecraft and the earth by reflection from the surfaces of planets are used to infer geophysical properties on planetary surfaces. STARLab professors and students are involved in all of NASA's current planetary flight missions. The experimental program motivates and is supported by ongoing work in advanced theories of wave propagation and scattering. These theoretical and experimental programs are supported by active research in the area of signal processing and efficient techniques in using digital processors.

STARLab members are also concerned with very low frequency research into the origin and properties of electromagnetic signals in the earth's environment, and their relation to other phenomena on and below the Earth's surface, in the upper atmosphere, and in interplanetary space. Both natural and man-made signals are involved in this research. Measurements are taken at a number of locations around the world, including Greenland, Antartica, and Alaska. Of particular interest is the investigation of lightning discharges and their effects of Earth's ionized atmosphere. STARLab also conducts measurements of ultra low frequency waves of natural origin at various sites around the world. Recent measurements in California have led to the discovery that major earthquakes may be preceded by ultra low frequency electromagnetic signals. As a result, additional measurement systems are being built and installed along the San Andreas fault in California. This research will become a cooperative effort with the School of Earth Sciences.

Another area of research involves the application of interferometric synthetic aperture radar to problems in the physics of the solid earth. This field, which is in its infancy, utilizes precision radar methods to measure both the surface topography at meter-level accuracies and also centimeter-level changes in the shape of the earth's surface, which provide large-area, fine resolution surface deformation measurements. The area is being developed in joint work between STARLab and the Department of Geophysics, concentrating particularly on volcanologic and seismic applications.

STARLab maintains a variety of computer systems and workstations for use in signal and data analysis. Some of these machines are equipped with graphics capabilities as well as software tools for system and VLSI hardware design.

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