The Karoo Array Telescope [KAT] is a South African project that is attempting to build a worldclass radio telescope in the Northern Cape. The first prototype phase of the project was called the eXperimental Development Model or XDM. This MSc project involves the development of a carrier card that was planned to be used for XDM. The card, called the XDM Carrier Card, or XCC, was designed to be used as part of a modular Digital Signal Processing [DSP] architecture.
The XCC’s external connections are summarized in the context diagram in Figure 1. The card was designed to support two daughter cards, high-speed data network connections, a control network connection and power and synchronization signals from a backplane. The modular architecture was chosen to allow the boards to operate in different modes, depending on the application, for example, as digital receivers or data processors. The primary function of the carrier card was to perform communication and control tasks.
Typically, radio astronomy applications require substantial DSP hardware to sample, process and transfer incoming data. The demands on DSP performance are growing rapidly, as new instruments incorporate more dishes and seek improved performance. In the past, these instruments were designed for very narrow applications and took anything between three and ten years to develop. However, the fast growth of the processing power of electronics often rendered these designs obsolete even before they were deployed.
In the last decade, Field Programmable Gate Arrays [FPGAs] have provided an agile means of performing DSP. They facilitate rapid development of digital systems and lend themselves to relatively simple hardware as they increasingly allow more tasks to be performed on a single Integrated Circuit [IC]. These features allow for frequent updates of hardware, allowing the Moore’s Law curve to be followed. For these reasons, FPGAs have been widely adopted for use in radio astronomy projects, such as the Allen Telescope Array and in KAT itself. Thus, FPGAs form a central theme in the design of the XCC.