James M. Noras

Aperture-Coupled Asymmetric Dielectric Resonators Antenna for Wideband Applications

A compact dielectric resonator antenna (DRA) for wideband applications is proposed. Two cylindrical dielectric resonators that are asymmetrically located with respect to the center of a rectangular coupling aperture are fed through this aperture. By optimizing the design parameters, an impedance bandwidth of about 29%, covering the frequency range from 9.62 to 12.9 GHz, and a gain of 8 dBi are obtained. Design details of the proposed antenna and the results of both simulation and experiment are presented and discussed.

Novel design of multiplier-less FFT processors

This paper presents a novel and hardware-efficient architecture for power-of-two FFT processors. The proposed design is based on the phase-amplitude splitting technique which converts a DFT to cyclic convolutions and additions. The cyclic convolutions are implemented with a filter-like structure and the additions are computed with several stages of butterfly processing units. The proposed architecture requires no multiplier, and comparisons with other designs show it can save up to 39% total equivalent gates for an 8-bit 16-point FPGA-based FFT processor.

Reconfigurable turbo decoding for 3G applications

Software radio and reconfigurable systems represent reconfigurable functionalities of the radio interface. Considering turbo decoding function in battery-powered devices like 3GPP mobile terminals, it would be desirable to choose the optimum decoding algorithm: SOVA in terms of latency, and log-MAP in terms of performance. In this paper it is shown that the two algorithms share common operations, making feasible a reconfigurable SOVA/log-MAP turbo decoder with increased efficiency. Moreover, an improvement in the performance of the reconfigurable architecture is also possible at minimum cost, by scaling the extrinsic information with a common factor. The implementation of the improved reconfigurable decoder within the 3GPP standard is also discussed, considering different scenarios. In each scenario various frame lengths are evaluated, while the four possible service classes are applied. In the case of AWGN channels, the optimum algorithm is proposed according to the desired quality of service of each class, which is determined from latency and performance constraints. Our analysis shows the potential utility of the reconfigurable decoder, since there is an optimum algorithm for most scenarios.

Variable length equalizers for broadband mobile systems

The very high bit rates of modern mobile systems (2.5G and 3G) demand powerful channel distortion mitigation, and for this role, equalization is a possible candidate. In this paper the importance of the length of linear equalizers is analyzed. It is shown that accurate control of equalizer length can improve the systems performance and also reduce the handset power consumption.

A novel approach for pileup detection in gamma-ray spectroscopy using deconvolution

In this paper, we propose a new approach for online detection of pileup in gamma-ray spectroscopy using finite length deconvolution filters. The approach was tested in resolving pileup with an average success of 93%. We show that the number of pileup events can be reduced by eightfold using the proposed approach. Gamma pulses, from a 3 inch Na(Tl) scintillation detector, were captured as single and double pulses for the purpose of testing the proposed peak detection algorithm. The algorithms developed here were then implemented in real time using a high performance floating-point processor, TMS320C6711.

Statistical Analysis of Refractivity Gradient and

In this communication, nine years of local radiosonde meteorological data, from 1997 to 2005, have been used to calculate the vertical refractivity gradient, ΔN, in the lowest atmospheric layer above the ground surface. The values obtained are used to estimate the parameter β₀, which represents the probability of non-standard propagation. Hourly, monthly and yearly distributions of ΔN in the first 100 meters above the ground are given. Monthly and yearly variations of the mean of ΔN and β₀ are provided and the β₀ values are compared with the ITU maps.

\beta_{0}

A fast three-step search (FTSS) block matching algorithm for motion estimation is described. The method is based on the real world image sequences characteristic of centre-biased motion vector distribution and uses centre-biased checking point patterns and a small number of search locations to perform fast block matching. Computational complexity is reduced by employing an 11 x 11 search window rather than the traditional 15 x 15 window. Simulation results are presented which show that the FTSS algorithm provides competitive performance at faster speed when compared with similar techniques such as full search (FS), three-step search (TSS), new three-step search (NTSS) and four-step search (4SS). The advantages of the novel algorithm for hardware implementation are discussed with particular relevance to applying it to video coding.

Parameter in the Gulf Region

Near-field imaging using microwaves in medical applications is of great current interest for its capability and accuracy in identifying features of interest, in comparison with other known screening tools. This paper documents microwave imaging experiments on breast cancer detection, using active antenna tuning to obtain matching over a wide bandwidth. A simple phantom consisting of a plastic container with a low dielectric material emulating fatty tissue and a high dielectric constant object emulating a tumor is scanned between 4 and 8 GHz with a ultra-wideband microstrip antenna. Measurements indicate that this prototype microwave sensor is a good candidate for such imaging applications.

A Novel Fast Three-Step Search Algorithm for Block-Matching Motion Estimation

A new hybrid method of moments (MoM)/finite-difference timsdomain (FDTD), with a sub-gridded finite-difference timedomain (SGFDTD) approach is presented. The method overcomes the drawbacks of homogeneous MOM and FDTD simulations, and so permits accurate analysis of realistic applications. As a demonstration, it is applied to the short-range interaction between an inhomogeneous human body and a small UHF WID antenna tag, operating at, 900MHz. Near-field and far-field performance for the antenna are assessed for different placements over the body. The cumulativt. distribution function of the radiation efficiency and the absorbed power are presented and analyzed. The algorithm has a fivefold speed advantage over fine-gridded FDTD.

An Active Microwave Sensor for Near Field Imaging

IIR filters designed for steady state operation suffer from the transient effect caused by processing a finite number of samples. Their performance, however, can be improved by using initialization techniques. This paper presents a new design method of IIR filters when processing a limited number of samples. An equivalent FIR filter for an IIR filter with multiple-frequency initializations is derived. This is then used in a design method that minimizes the mean squared-error between the steady state and the transient frequency responses. Filters designed using this method are shown to offer better transient frequency responses when compared to conventional steady state filters with and without initialization.