Browsing by Subject "Electrical and computer engineering"

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    Design of a Delta-sigma fractional-N PLL frequency synthesizer at 1.43GHz
    (2012-07) Soldner, Thomas M.
    PLL-based frequency synthesis is a common method for developing highly stable oscillators.The need for this type of synthesizer that can operate at non-integer multiples of a reference oscillator is growing. Delta-sigma modulators used to control the division ratio in PLL-based fractional-N frequency synthesizers help to meet the growing need for synthesizers operating at non-integer multiples. A PLLbased fractional-N frequency synthesizer using a delta-sigma modulator to control the division ratio was analyzed at the system level and implemented at transistor level. The system level analysis consisted of understanding the effect of the deltasigma modulator on spurious tone reduction in the synthesizer output. Circuit blocks were then designed individually at transistor level. Results of the delta-sigma output and the overall synthesizer were then discussed. The synthesizer achieved a start-up speed of 4sec. The in-band phase noise performance was -82 dBc/Hz at 3 MHzoffset from the carrier.
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    Development and field demonstration of DSRC-based traffic information system for the work zone.
    (2011-12) Maitipe, Buddhika Ruwan
    This report describes the architecture, functionality and the field demonstration results of a newly developed DSRC based V2I work zone traffic information system with V2V assistance. The developed system can automatically acquire important work zone travel information, e.g., the travel time (TT) and the starting location of congestion (SLoC), and relay them back to the drivers approaching the congestion site. Such information can help drivers in making informed decisions on route choice and/or preparing for upcoming congestion. Previously, we designed such a system using DSRC based V2I-only communication, which could not handle longer congestion lengths and the message broadcast range was also very limited. Our current system, on the other hand, can achieve much longer broadcast range (up to a few tens of kms), and can handle much longer congestion coverage length (up to a few kms) by incorporating DSRC-based V2I communication with V2V assistance. The new system is also portable and uses only one RSU, which can acquire traffic data by engaging the vehicles traveling on the roadside whether within or outside of its direct wireless access range. From the traffic data, it estimates important traffic parameters, i.e., TT and SLoC, and periodically broadcasts them back to the vehicles approaching the congestion well before they enter the congested area. The results from the field demonstration have indicated that the new system can adapt to dynamically changing work zone traffic environment and can handle much longer congestion lengths as compared to previous system using V2I-only communication without V2V assistance.