Code synchronization and interference management techniques for satellite navigation and communications

This thesis collects the outcomes of a Ph.D. course in Telecommunications engineering and it is focused on enabling techniques for Spread Spectrum (SS) navigation and communication satellite systems. It provides innovations for both interference management and code synchronization techniques. These two aspects are critical for modern navigation and communication systems and constitute the common denominator of the work. The thesis is organized in two parts: the former deals with interference management. We have proposed a novel technique for the enhancement of the sensitivity level of an advanced interference detection and localization system operating in the Global Navigation Satellite System (GNSS) bands, which allows the identification of interfering signals received with power even lower than the GNSS signals. Moreover, we have introduced an effective cancellation technique for signals transmitted by jammers, exploiting their repetitive characteristics, which strongly reduces the interference level at the receiver. The second part, deals with code synchronization. More in detail, we have designed the code synchronization circuit for a Telemetry, Tracking and Control system operating during the Launch and Early Orbit Phase; the proposed solution allows to cope with the very large frequency uncertainty and dynamics characterizing this scenario, and performs the estimation of the code epoch, of the carrier frequency and of the carrier frequency variation rate. Furthermore, considering a generic pair of circuits performing code acquisition, we have proposed a comprehensive framework for the design and the analysis of the optimal cooperation procedure, which minimizes the time required to accomplish synchronization. The study results particularly interesting since it enables the reduction of the code acquisition time without increasing the computational complexity. Finally, considering a network of collaborating navigation receivers, we have proposed an innovative cooperative code acquisition scheme, which allows exploit the shared code epoch information between neighbor nodes, according to the Peer-to-Peer paradigm.

Essays in Media and Finance

This Ph.D. thesis consists in three research papers focused on the relationship between media industry and the financial sector. The importance of a correct understanding what is the effect of media on financial markets is becoming increasingly important as long as fully informed markets hypothesis has been challenged. Therefore, if financial markets do not have access to complete information, the importance of information professionals, the media, follows. On the other side, another challenge for economic and finance scholar is to understand how financial features are able to influence media and to condition information disclosure. The main aim of this Ph.D. dissertation is to contribute to a better comprehension for both the phenomena. The first paper analyzes the effects of owning equity shares in a newspaper- publishing firm. The main findings show how for a firm being part of the ownership structure of a media firm ends to receive more and better coverage. This confirms the view in which owning a media outlet is a source of conflicts of interest. The second paper focuses on the effect of media-delivered information on financial markets. In the framework of IPO in the U.S. market, we found empirical evidence of a significant effect of the media role in the IPO pricing. Specifically, increasing the quantity and the quality of the coverage increases the first-day returns (i.e. the underpricing). Finally the third paper tries to summarize what has been done in studying the relationship between media and financial industries, putting together contributes from economic, business, and financial scholars. The main finding of this dissertation is therefore to have underlined the importance and the effectiveness of the relationship between media industry and the financial sector, contributing to the stream of research that investigates about the media role and media effectiveness in the financial and business sectors.