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Abstmct-The performance and optimization of switched diversity systems are considered.First, the one-dimensional distribution and probability density functions of the envelope of the received signal are obtained for three different switching strategies. This information is used to obtain the average probability of bit error for the case of non-coherent detection of binary FSK signals with Rayleigh fading envelopes and additive white Gaussian noise. The optimization of two of these switching strategies is then considered, and it is shown that by proper selection of switching thresholds, the average probability of bit error during detection can be minimized. It is also shown that these optimized switching strategies yield a significant improvement in performance over non-diversity systems and can approach the performance of more complex receivers such as maximal ratio combining. Computer simulations of switched diversity sytems using a practical field model are used to verify the analysis.

This paper describes the current efforts underway to set up matched long-term continuously running spectrum observatories in the US (in Chicago and Blacksburg) and in Turku, Finland. The measurement equipment setup is described, along with the architecture for the networked database used to aggregate, archive and share the spectrum measurement data collected across the multiple international locations. High performance computer infrastructure to permit analysis and as appropriate fusion specific elements of the terabytes of data is described. The measurement parameters and spectrum measurement band plans are listed. Preliminary analysis results are also provided-particularly, simple occupancy statistics in Chicago and in Turku. To demonstrate the utility of the global spectrum observatory network, an interesting example is provided that compares and contrasts the very different signals that occupy the same spectral band, but in different geographic regions.

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In 2007, the Wireless Network and Communications (WiNCom) Research Center at the Illinois Institute of Technology initiated a continuous RF spectrum measurement program in the frequency range 30 MHz to 6 GHz. The data measurement collection, now multiple Terabytes, was historically stored in a flat file format on multiple hard drives which was efficient and easy to deal with from a data collection perspective, but not very effective from an analysis and sharing perspective. This paper describes the data capture structure, the new database and data storage approach that has been created to enable large scale, "safe storage", and to facilitate data queries and RF measurement analysis by researchers both inside and outside of IIT's network, and some of the application that have been implemented using this new structure.