Wideband digital instrumentation for the Italian radio telescopes

Italy has a key role in the radio astronomical international context thanks to large collaborations like the VLBI (Very Long Baseline Interferometry) in which all three radio telescopes (Sardinia,Medicina, Noto) are deeply involved. However, also the single dish activity represents a great opportunity to understand the fundamental laws of nature in the Universe. Usually, in the past, ad-hoc digital backends were developed for each particular scientific goal; however, although highly optimised, they very often do not keep upwith the times. In addition to the absent versatility even if based on reconfigurable FPGA-based hardware, the major issue why digital backends are often obsolete - even before they can be fully exploited - is the very long time necessary to make them integrated into the software controlling the radio telescope. In this thesis, a different approach - both regarding hardware and software - has been developed to overcome aforementioned drawbacks and is described here. The unprecedented achieved scientific results are presented in different fields (imaging, polarimetry, spectroscopy, pulsars), and confirm the forcefulness of the adopted solution. The versatility of the proposed infrastructure also allows us the development of innovative spectrometers, which are able to meet the main requirements astronomers asking us: wide-bandwidth, high-spectral resolution and an uniform passband response (namely, no spectral “holes”). Finally, we describe an innovative infrastructure for the SETI (Search for ExtraTerrestrial Intelligence) international program. In particular, the KLT (Kahrunen-Loeve Transform) has been investigated togetherwith the FFT approach usually adopted.