Wideband Digital Technology for Radio Astronomy

As radio astronomy receiver bandwidth increases, it is necessary to increase the speed of analog-to-digital conversion (ADC) as well as the digital signal processing (DSP) in the telescope's back end. Otherwise a complex and expensive mixer-filter system is needed, to break the IF bandwidth into smaller blocks for digital sampling and signal processing. Analog-to-digital converters (ADC) capable of sample rates five gigasamples-per-second and faster are now available and DSP technology has been following Moore's law to provide matching processing power. In current wideband instruments, usable bandwidth blocks ~2 GHz can be processed digitally, and we envisage a near term future where blocks ~10 GHz might be handled by a single compact module. This paper reviews ultra-wideband ADC and DSP technology, and describes examples of wideband processing in radio astronomy correlators and phased arrays.