Transmitter Equalization for 4Gb/s Signalling

To operate a serial channel over copper wires at 4Gb/s, we incorporate an 4GHz FIR equalizing filter into a differential transmitter. The equalizer cancels the frequency-dependent attenuation caused by the skin-effect resistance of copper wire giving a frequency response that is flat to within 5% over the band from 200MHz to 2GHz even over wires with 6dB of high-frequency attenuation. All but the last stage of the transmitter operates at 400MHz. The transmitter output stage uses a stable 10-phase 400MHz clock to sequence an array of drivers that implement the FIR filter. This paper introduces the concept of digital-signal equalization, describes the system design and circuit design of our equalizing transmitter, and presents simulation results from a 4Gb/s 0.5µm CMOS transmitter. 1. Introduction The performance of many digital systems is limited by the interconnection bandwidth between chips, boards, and cabinets. As VLSI technology continues to scale, system bandwidth will become an ..

Investigating the Optical Link Performance of the End-of Substructure Card and Susceptibility to SEUs

Particle physics experiments carried out by CERN attempt to investigate the fundamental forces of matter. One of these experiments is the ATLAS experiment, which studies the proton-proton collisions in the LHC. A series of upgrades are planned to increase the luminosity by a factor of five, leading to the high-luminosity LHC (HL-LHC). This upgrade will increase the potential for new discoveries but brings with it design challenges in relation to the harsh radiation environment and significant data throughput required. The ATLAS experiment is building a new detector to cope with these challenges, titled the Inner Tracker (ITk). A crucial part of this new detector is the End-of-Substructure (EoS) card, which constitutes the interface between the ondetector electronics and the off-detector systems. In addition to the operational challenges, the HL-LHC does not allow for repairs or replacing of EoS cards once operation commences, emphasizing the need for thorough testing and qualification of this component. This thesis focuses on characterizing the performance of the EoS card in the presence of radiation, under non-ideal operating conditions and the impact of optical link parameters. The first set of tests is centered on qualifying the radiation tolerance of the EoS card. The radiation environment within the ITk poses a threat to the stable operation of electronics as energetic particles have the potential to cause erroneous changes in device logic, known as Single Event Upsets (SEU). The SEU susceptibility of the EoS card, with a focus on the Versatile Link Plus Transceiver (VTRx+) component, is studied by irradiating the EoS card with a neutron source with a distributed energy spectrum and a peak energy of 11MeV while performing a bit error rate (BER) test to monitor for radiation induced errors. The second set of tests deals with characterizing the impact of an irregular power supply on the EoS card's performance through simulating noise on the supply lines and monitoring the response in BER. The final set of tests investigates the impact the VTRx+ configuration parameters have on the quality of the optical signal. These tests were carried out at the University of Cape Town (UCT) with the support of DESY, a national research institute in Germany, responsible for the production of the EoS cards. A number of new firmware, software and hardware modules were developed as part of this work in order to carry out the tests required. The most significant of which comprised a novel firmware addition allowing for the evaluation of the optical signal quality with an FPGA. This contribution is now being integrated into the quality control proceedings at DESY, to be used in assessing optical signal quality of the entire set of approximately 1552 EoS cards being produced

ANALYSIS AND OPTIMIZATION OF ELECTRICAL SYSTEMS IN A SOLAR CAR WITH APPLICATIONS TO GATO DEL SOL III-IV

Gato del Sol III, was powered by a solar array of 480 Silicon mono-crystalline photovoltaic cells. Maximum Power Point trackers efficiently made use of these cells and tracked the optimal load. The cells were mounted on a fiber glass and foam core composite shell. The shell rides on a lightweight aluminum space frame chassis, which is powered by a 95% efficient brushless DC motor. Gato del Sol IV was the University of Kentucky Solar Car Team’s (UKSCT) entry into the American Solar Car Challenge (ASC) 2010 event. The car makes use of 310 high density lithium-polymer batteries to account for a 5 kWh pack, enough to travel over 75 miles at 40 mph without power generated by the array. An in-house battery protection system and charge balancing system ensure safe and efficient use of the batteries. Various electrical sub-systems on the car communicate among each other via Controller Area Network (CAN). This real time data is then transmitted to an external computer via RF communication for data collection

Structures and materials technology needs for communications and remote sensing spacecraft

This report documents trade studies conducted from the perspective of a small spacecraft developer to determine and quantify the structures and structural materials technology development needs for future commercial and NASA small spacecraft to be launched in the period 1999 to 2005. Emphasis is placed on small satellites weighing less than 1800 pounds for two focus low-Earth orbit missions: commercial communications and remote sensing. The focus missions are characterized in terms of orbit, spacecraft size, performance, and design drivers. Small spacecraft program personnel were interviewed to determine their technology needs, and the results are summarized. A systems-analysis approach for quantifying the benefits of inserting advanced state-of-the-art technologies into a current reference, state-of-the-practice small spacecraft design is developed and presented. This approach is employed in a set of abbreviated trade studies to quantify the payoffs of using a subset of 11 advanced technologies selected from the interview results The 11 technology development opportunities are then ranked based on their relative payoff. Based on the strong potential for significant benefits, recommendations are made to pursue development of 8 and the 11 technologies. Other important technology development areas identified are recommended for further study

Towards a distributed real-time system for future satellite applications

Thesis (MScEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The Linux operating system and shared Ethernet are alternative technologies with the potential to reduce both the development time and costs of satellites as well as the supporting infrastructure. Modular satellites, ground stations and rapid proto typing testbeds also have a common requirement for distributed real-time computation. The identified technologies were investigated to determine whether this requirement could also be met. Various real-time extensions and modifications are currently available for the Linux operating system. A suitable open source real-time extension called Real-Time Application Interface (RTAI) was selected for the implementation of an experimental distributed real-time system. Experimental results showed that the RTAI operating system could deliver deterministic realtime performance, but only in the absence of non-real-time load. Shared Ethernet is currently the most popular and widely used commercial networking technology. However, Ethernet wasn't developed to provide real-time performance. Several methods have been proposed in literature to modify Ethernet for real-time communications. A token passing protocol was found to be an effective and least intrusive solution. The Real-Time Token (RTToken) protocol was designed to guarantee predictable network access to communicating real-time tasks. The protocol passes a token between nodes in a predetermined order and nodes are assigned fixed token holding times. Experimental results proved that the protocol offered predictable network access with bounded jitter. An experimental distributed real-time system was implemented, which included the extension of the RTAI operating system with the RTToken protocol, as a loadable kernel module. Real-time tasks communicated using connectionless Internet protocols. The Real-Time networking (RTnet) subsystem of RTAI supported these protocols. Under collision-free conditions consistent transmission delays with bounded jitter was measured. The integrated RTToken protocol provided guaranteed and bounded network access to communicating real-time tasks, with limit overheads. Tests exhibited errors in some of the RTAI functionality. Overall the investigated technologies showed promise in being able to meet the distributed real-time requirements of various applications, including those found in the satellite environment.AFRIKAANSE OPSOMMING: Die Linux bedryfstelsel en gedeelde Ethernet is geïdentifiseer as potensiële tegnologieë vir satelliet bedryf wat besparings in koste en vinniger ontwikkeling te weeg kan bring. Modulêr ontwerpte satelliete, grondstasies en ontwikkeling platforms het 'n gemeenskaplike behoefte vir verspreide intydse verwerking. Verskillende tegnologieë is ondersoek om te bepaal of aan die vereiste ook voldoen kan word. Verskeie intydse uitbreidings en modifikasies is huidiglik beskikbaar vir die Linux bedryfstelsel. Die "Real-Time Application Interface" (RTAI) bedryfstelsel is geïdentifiseer as 'n geskikte intydse uitbreiding vir die implementering van 'n eksperimentele verspreide intydse stelsel. Eksperimentele resultate het getoon dat die RTAI bedryfstelsel deterministies en intyds kan opereer, maar dan moet dit geskied in die afwesigheid van 'n nie-intydse verwerkingslas. Gedeelde Ethernet is 'n kommersiële network tegnologie wat tans algemeen beskikbaar is. Die tegnologie is egter nie ontwerp vir intydse uitvoering nie. Verskeie metodes is in die literatuur voorgestelom Ethernet te modifiseer vir intydse kommunikasie. Hierdie ondersoek het getoon dat 'n teken-aangee protokol die mees effektiewe oplossing is en waarvan die implementering min inbreuk maak. Die "Real-Time Token" (RTToken) protokol is ontwerp om voorspelbare netwerk toegang tot kommunikerende intydse take te verseker. Die protokol stuur 'n teken tussen nodusse in 'n voorafbepaalde volgorde. Nodusse word ook vaste teken hou-tye geallokeer. Eksperimentele resultate het aangedui dat die protokol deterministiese netwerk toegang kan verseker met begrensde variasies. 'n Eksperimentele verspreide intydse stelsel is geïmplementeer. Dit het ingesluit die uitbreiding van die RTAI bedryfstelsel met die RTToken protokol; verpak as 'n laaibare bedryfstelsel module. Intydse take kan kommunikeer met verbindinglose protokolle wat deur die "Real-Time networking" (RTnet) substelsel van RTAI ondersteun word. Onder ideale toestande is konstante transmissie vertragings met begrensde variasies gemeet. Die integrasie van die RTToken protokol het botsinglose netwerk toegang aan kommunikerende take verseker, met beperkte oorhoofse koste as teenprestasie. Eksperimente het enkele foute in die funksionaliteit van RTAI uitgewys. In die algemeen het die voorgestelde tegnologieë getoon dat dit potensiaal het vir verskeie verspreide intydse toepassings in toekomstige satelliet en ook ander omgewings

Earth imaging with microsatellites: An investigation, design, implementation and in-orbit demonstration of electronic imaging systems for earth observation on-board low-cost microsatellites.

This research programme has studied the possibilities and difficulties of using 50 kg microsatellites to perform remote imaging of the Earth. The design constraints of these missions are quite different to those encountered in larger, conventional spacecraft. While the main attractions of microsatellites are low cost and fast response times, they present the following key limitations: Payload mass under 5 kg, Continuous payload power under 5 Watts, peak power up to 15 Watts, Narrow communications bandwidths (9.6 / 38.4 kbps), Attitude control to within 5°, No moving mechanics. The most significant factor is the limited attitude stability. Without sub-degree attitude control, conventional scanning imaging systems cannot preserve scene geometry, and are therefore poorly suited to current microsatellite capabilities. The foremost conclusion of this thesis is that electronic cameras, which capture entire scenes in a single operation, must be used to overcome the effects of the satellite's motion. The potential applications of electronic cameras, including microsatellite remote sensing, have erupted with the recent availability of high sensitivity field-array CCD (charge-coupled device) image sensors. The research programme has established suitable techniques and architectures necessary for CCD sensors, cameras and entire imaging systems to fulfil scientific/commercial remote sensing despite the difficult conditions on microsatellites. The author has refined these theories by designing, building and exploiting in-orbit five generations of electronic cameras. The major objective of meteorological scale imaging was conclusively demonstrated by the Earth imaging camera flown on the UoSAT-5 spacecraft in 1991. Improved cameras have since been carried by the KITSAT-1 (1992) and PoSAT-1 (1993) microsatellites. PoSAT-1 also flies a medium resolution camera (200 metres) which (despite complete success) has highlighted certain limitations of microsatellites for high resolution remote sensing. A reworked, and extensively modularised, design has been developed for the four camera systems deployed on the FASat-Alfa mission (1995). Based on the success of these missions, this thesis presents many recommendations for the design of microsatellite imaging systems. The novelty of this research programme has been the principle of designing practical camera systems to fit on an existing, highly restrictive, satellite platform, rather than conceiving a fictitious small satellite to support a high performance scanning imager. This pragmatic approach has resulted in the first incontestable demonstrations of the feasibility of remote sensing of the Earth from inexpensive microsatellites

A survey and evaluation of microbased computer aided design systems for design education and practice in Scotland primarily in the area of product design: their application, problems and potential solutions

The initial premise of the research centred around the relatively new adoption by the Product Design sector of Computer Aided Design technology. Problems were expected to occur in applying the hardware and understanding the terminology of the software by this sector which prides itself In its artisan skills. The aim of the work was to determine the extent of the adoption of Computer Aided Design and to clarify the problem areas. The research determined, by study of more experienced but similar Computer Aided Design users, that the expected problems Were not insurmountable and were being overcome by the constant improvements of computer hardware and software. However, the problems that were pinpointed actually involved the human issues encountered In working with a Computer Aided Design system and involved issues such as the management skills required, working conditions and understanding of the advantages and disadvantages of Computer Aided Design. The research focused on what had to be considered and what should be known about Computer Aided Design so that it could be effectively used in Product Design. The research was undertaken to establish general solutions to the introduction of Computer Aided Design into companies. These solutions are intended to provide a guide to potential and current users on how to improve the effectiveness of the use of Computer Aided Design systems in Product Design. The research has identified the themes and topics that should be covered in training staff on the use and potential of Computer Aided Design systems