Optical fibre measurement for clock tones in telescope networks

Astronomy dates back to the early man’s impression of the heavens with little information recorded including some drawings of comets, eclipse and supernovas[1]. Major progress has been made in the field of Astronomy since then. Scientific curiosity to probe the universe in attempt to answer questions such as the origin of the universe, the matter it is made of, the formation of stars, planets and galaxies, and tracking life in other solar systems has brought about the need for more advanced tools capable of detailed observations. In 1608 H. Lippershey developed the first refracting telescope[2], [3]. A year later Galileo used a similar telescope pointing skywards discovering mountains and craters on the earth’s moon, the moons of Jupiter and the phases of Venus. Over the years telescopes have been developed with advancements from the optical telescope towards much larger and more sensitive radio telescopes. The first radio signal from space was detected by Karl Jansky and ever since then astronomers have been using radio telescopes to explore the universe by detecting radio waves emitted by cosmic objects[4]. The ability of radio telescopes to detect weak signals is related to the signal capture surface. As the demand for sensitivity, transmission bandwidth and data rate increases, so does the need for telescopes with a large field of view and capability to observe different parts of the sky at once[5]. This is possible with radio telescope array, with the data from the antennas combined electronically to produce a high resolution image of the sky. The South African MeerKAT radio telescope is an array of 64 interlinked antennas each transmitting up to 160 Gbps of data to the central processing site over optical fibre which is ideal for carrying large volumes of data at high speeds. The MeerKAT telescope is a precursor to the Square kilometer Array which will have up to 50 times the sensitivity and 10000 times the survey speed than the best telescope[6]

Development and Experimental Analysis of Wireless High Accuracy Ultra-Wideband Localization Systems for Indoor Medical Applications

This dissertation addresses several interesting and relevant problems in the field of wireless technologies applied to medical applications and specifically problems related to ultra-wideband high accuracy localization for use in the operating room. This research is cross disciplinary in nature and fundamentally builds upon microwave engineering, software engineering, systems engineering, and biomedical engineering. A good portion of this work has been published in peer reviewed microwave engineering and biomedical engineering conferences and journals. Wireless technologies in medicine are discussed with focus on ultra-wideband positioning in orthopedic surgical navigation. Characterization of the operating room as a medium for ultra-wideband signal transmission helps define system design requirements. A discussion of the first generation positioning system provides a context for understanding the overall system architecture of the second generation ultra-wideband positioning system outlined in this dissertation. A system-level simulation framework provides a method for rapid prototyping of ultra-wideband positioning systems which takes into account all facets of the system (analog, digital, channel, experimental setup). This provides a robust framework for optimizing overall system design in realistic propagation environments. A practical approach is taken to outline the development of the second generation ultra-wideband positioning system which includes an integrated tag design and real-time dynamic tracking of multiple tags. The tag and receiver designs are outlined as well as receiver-side digital signal processing, system-level design support for multi-tag tracking, and potential error sources observed in dynamic experiments including phase center error, clock jitter and drift, and geometric position dilution of precision. An experimental analysis of the multi-tag positioning system provides insight into overall system performance including the main sources of error. A five base station experiment shows the potential of redundant base stations in improving overall dynamic accuracy. Finally, the system performance in low signal-to-noise ratio and non-line-of-sight environments is analyzed by focusing on receiver-side digitally-implemented ranging algorithms including leading-edge detection and peak detection. These technologies are aimed at use in next-generation medical systems with many applications including surgical navigation, wireless telemetry, medical asset tracking, and in vivo wireless sensors

Design Techniques for High Pin Efficiency Wireline Transceivers

While the majority of wireline research investigates bandwidth improvement and how to overcome the high channel loss, pin efficiency is also critical in high-performance wireline applications. This dissertation proposes two different implementations for high pin efficiency wireline transceivers. The first prototype achieves twice pin efficiency than unidirectional signaling, which is 32Gb/s simultaneous bidirectional transceiver supporting transmission and reception on the same channel at the same time. It includes an efficient low-swing voltage-mode driver with an R-gm hybrid for signal separation, combining the continuous-time-linear-equalizer (CTLE) and echo cancellation (EC) in a single stage, and employing a low-complexity 5/4X CDA system. Support of a wide range of channels is possible with foreground adaptation of the EC finite impulse response (FIR) filter taps with a sign-sign least-mean-square (SSLMS) algorithm. Fabricated in TSMC 28-nm CMOS, the 32Gb/s SBD transceiver occupies $0.09 mm^{2}$ area and achieves 16Gb/s uni-directional and 32Gb/s simultaneous bi-directional signals. 32Gb/s SBD operation consumes 1.83mW/Gb/s with 10.8dB channel loss at Nyquist rate. The second prototype presents an optical transmitter with a quantum-dot (QD) microring laser. This can support wavelength-division multiplexing allowing for high pin efficiency application by packing multiple high-bandwidth signals onto one optical channel. The development QD microring laser model accurately captures the intrinsic photonic high-speed dynamics and allows for the future co-design of the circuits and photonic device. To achieve higher bandwidth than intrinsic one, utilizing both techniques of optical injection locking (OIL) and 2-tap asymmetric Feed-forward equalizer (FFE) can perform 22Gb/s operation with 3.2mW/Gb/s. The first hybrid-integration directly-modulated OIL QD microring laser system is demonstrated

Eighth International Workshop on Laser Ranging Instrumentation

The Eighth International Workshop for Laser Ranging Instrumentation was held in Annapolis, Maryland in May 1992, and was sponsored by the NASA Goddard Space Flight Center in Greenbelt, Maryland. The workshop is held once every 2 to 3 years under differing institutional sponsorship and provides a forum for participants to exchange information on the latest developments in satellite and lunar laser ranging hardware, software, science applications, and data analysis techniques. The satellite laser ranging (SLR) technique provides sub-centimeter precision range measurements to artificial satellites and the Moon. The data has application to a wide range of Earth and lunar science issues including precise orbit determination, terrestrial reference frames, geodesy, geodynamics, oceanography, time transfer, lunar dynamics, gravity and relativity

Zeroth-order design report for the next linear collider. Volume 1

This Zeroth Order Design Report (ZDR) for the Next Linear Collider (NLC) has been completed as a feasibility study for a TeV-scale linear collider that incorporates a room-temperature accelerator powered by rf microwaves at 11.424 GHz--similar to that presently used in the SLC, but at four times the rf frequency. The purpose of this study is to examine the complete systems of such a collider, to understand how the parts fit together, and to make certain that every required piece has been included. The design presented here is not fully engineered in any sense, but to be assured that the NLC can be built, attention has been given to a number of critical components and issues that present special challenges. More engineering and development of a number of mechanical and electrical systems remain to be done, but the conclusion of this study is that indeed the NLC is technically feasible and can be expected to reach the performance levels required to perform research at the TeV energy scale. Volume one covers the following: the introduction; electron source; positron source; NLC damping rings; bunch compressors and prelinac; low-frequency linacs and compressors; main linacs; design and dynamics; and RF systems for main linacs