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Table of Contents & Guest editorial (~440 kB)
1. New Implementation of RSFQ Superconductive Digital Gates
2. Performance analysis and Simplified detection for two-dimensional signal space diversity with MRC reception.
3. Ideal HT: a Houghtransform assesment tool.
4. Cold spray technology for high performance frequency selective conductive structures.
New Implementation of RSFQ SuperConductive Digital Gates
by R.S. Bakolo and C.J. Fourie
Abstract: We present additional RSFQ superconductive digital electronics logic gates that have been developed to complement already existing gates. These gates are the NOR, NAND and XNOR. The gates were designed, simulated and laid out for fabrication in both IPHT's FLUXONICS 1 kA/cm2 and Hypres' 4.5 kA/cm2 processes. Layout circuit parameters such as inductance were extracted to compare these with design values. Good working margins were obtained after several steps of manual circuit optimisation during the design and simulation stages.NioPulse, superconductor circuit design software developed by NioCAD in South Africa, was used and evaluated during the design process. Download Paper (~752 kB)
Performance Analysis and Simplified Detection for Two-Dimensional Signal Space Diversity with MRC reception
by Z. Paruk and H. Xu
Abstract: Signal space diversity (SSD) is a promising technique for obtaining diversity without increases in bandwidth, transmit power or physical hardware at the expense of increased ML detection complexity. Symbol error rate (SER) analysis of a two-dimensional system containing a single transmit antenna and N receive antennas with maximal-ratio combining (MRC) reception is presented here along with a simplified detection scheme for SSD systems. The union bound and the nearest neighbour (NN) approximation are presented in closed form, and a new, simpler SER bound for SSD systems based on the minimum Euclidean distance of a rotated constellation is presented, also in closed form. Performance of the new bound is found to be tight for low signal-to-noise ratios (SNRs), small rotation angles and when the number of receive antennas (N) is large; the new bound is also easily applied to other systems. The simplified detection scheme, while losing diversity and SER performance when N = 1, achieves a 7dB and 4dB performance improvement over non-SSD transmission at SERs of 10−3 and 10−2 for 4-QAM and 16-QAM respectively. However, when N ≥ 3, SER performance is close to indistinguishable from that of optimal ML detection while achieving complexity reductions of up to 5.77%, 70.19% and 91.77% for 4-QAM, 16-QAM and 64-QAM respectively. Download Paper (~450 KB)
Ideal HT: a Hough transform assessment tool
by C. Tu, Y. Hamam, B.J. van Wyk, K. Djouani and S. Du
Abstract: This paper addresses a method for the calculation of the ideal Hough Transform (HT) data of a segment. The calculation only depends on the basic physical facts (i.e. the endpoints of the segment), and therefore is free from the effect of discretisation errors in both image space and parameter space. The rounding errors in the voting process are also eliminated. The ideal HT data obtained is employed to evaluate the HT data generated by other HT varieties and alleviates the difficulties in assessing those HT algorithms. The performance of standard HT (SHT) is analyzed as an example.
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Cold Spray Technology for high performance Frequency Selective Conductive Structures
by I. Hofsajer and I. Botef
Abstract:Conductive structures and interconnects can be designed to exhibit a low pass filtering characteristic. This is accomplished by making use of the skin and proximity effects which confine high frequency currents to a reduced conductor cross sectional area. The efficacy of such filtering structures can be enhanced through the use of composite multi layer conductors, each layer with specific electric and magnetic properties. The widespread implementation of this type of filter has been limited by the difficulty in the layer design, manufacture and availability of materials with the correct properties. This paper discusses how each of these obstacles may be overcome and so doing opens up a large area of new potential applications
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