The commonly used classical equipartition or minimum-energy estimate of total magnetic fields strengths from radio synchrotron intensities is of limited practical use because it is based on the hardly known ratio K of the total energies of cosmic ray protons and electrons and also has inherent problems. We present a revised formula, using the number density ratio K for which we give estimates. ...

Uncertainty quantification is a critical missing component in radio interferometric imaging that will only become increasingly important as the big-data era of radio interferometry emerges. Statistical sampling approaches to perform Bayesian inference, like Markov Chain Monte Carlo (MCMC) sampling, can in principle recover the full posterior distribution of the image, from which uncertainties c...

TAO JIANG, Ph.D. THESIS, COMMUNICATIONS RESEARCH GROUP, UNIVERSITY OF YORK 2011 Abstract This thesis investigates how distributed reinforcement learning-based resource assignment algorithms can be used to improve the performance of a cognitive radio system. Decision making in most wireless systems today, including most cognitive radio systems in development, depends purely on instantaneous meas...

We review the uses of economic theory in the initial design and later improvement of the “simultaneous ascending auction,” which was developed initially for the sale of radio spectrum licenses in the US, with efficiency of the final allocation as the statutory goal. We analyze some capabilities and inherent limitations of the auction, the roles of various detailed rules, the possibilities for i...

Due to its advantages with respect to allowing simple receivers and flexibility, OFDM is – in addition to already existing systems such as DVB-T or HIPERLAN/2 – presently under consideration as auspicious candidate for future wireless communication air interface. However, despite many advantages, the lack of inherent diversity of pure OFDM based transmission schemes represents a major drawback....

The inherent non-linearity of mixers in communication systems creates numerous undesired effects, which are particularly acute in broadband receiver design for software defined radio (SDR) applications. In this paper, previously investigated mixer linearisation techniques are summarised, and a new technique using frequency retranslation is presented. To the author’s knowledge, this linearisatio...

Abstract. As the highest-energy photons, gamma rays have an inherent interest to astrophysicists and particle physicists studying high-energy, nonthermal processes. Gamma-ray telescopes complement those at other wavelengths, especially radio, optical, and X-ray, providing the broad, mutiwavelength coverage that has become such a powerful aspect of modern astrophysics. Multiwavelength techniques...

A time series analysis of observed solar radio pulsations suggests that there must be a low-dimensional attractor. The power spectrum cannot be interpreted as a superposition of periodic components. Estimates of the maximum Lyapunov exponent and of the Kolmogorov entropy give some indications for a deterministic chaos. In order to study the limitations inherent in small data samples we include ...