An Ska Engineering Overview Ska Engineering Overview -background Information System Considerations for the Ska

Chapter Title Page 1 SKA engineering overview – background information 3 2 System considerations for the SKA 6 3 Antenna concepts for the SKA 42 4 RF systems for the SKA 67 5 Signal transport for the SKA 79 6 SKA signal processing 97 7 RFI mitigation techniques in radio astronomy 116 8 Software for the SKA 128 9 The international SKA project: Industry liaison models and policies Since discussion of what is now called the Square Kilometre Array began in the late 1980s there have been many engineering concepts put forward for the Telescope. Perhaps not surprisingly, the traditional radio astronomy division between the small-D/large-N and large-D/small-N reflector camps emerged early and, by the time of an important Sydney meeting in 1997, there were also well-formed views on the merits of dense aperture arrays for operation below 1.5 GHz. As the science requirements began to creep beyond the original " hydrogen telescope " and the operating frequency range increased accordingly, it was clear even in 1997 that a combination of antenna technologies was needed. By the time of an international meeting at Berkeley in 2001 there were a number of ideas and performance claims on the table. One of the first actions of the newly-formed International Engineering and Management Team (IEMT) was to bring some order to the situation by asking concept proponents to write end-to-end exposition documents, in the form of discussion white papers. While these papers were to outline particular antenna and related technologies, they were very much seen as vehicles for presenting SKA overall system design ideas and preliminary cost estimates. Despite some initial scepticism, " best shot " concept white papers were completed and formed the basis of a most profitable science and engineering interaction in Groningen in 2002. As challenges emerged and responses were made, the papers and their revisions provided the basis for discussion over the ensuing years. Many of the later discussions centred on the feasibility of " hybrid " (or composite) designs incorporating more than one antenna concept. All of the white papers and many of the related documents are available via One of the more important outcomes of the 2002 SKA white paper process was the demonstration that concepts had far more in common than many of their proponents realized. Part of the Penticton gathering in 2004 involved an engineering retreat at which an elementary SKA cost and performance modelling …