A great deal of technical development work directly relevant to the Square Kilometer Array (SKA) and the future of existing radio telescopes is taking place in NRAO computing and electronics laboratories. Sometimes, this work goes unnoticed in the international arena of discussion of large future telescopes. To bring the results of the NRAO work to the attention of the astronomical community, the eNews will include a frequent "Lab Notebook" column. This column will feature non-technical descriptions of work that has been reported in journals, conferences, or internal reports with a brief description regarding how the work fits into NRAO's long-range research and development goals.
Clearly, the NRAO cannot be fully engaged in all technical development needed by SKA and other future radio instruments, so we are concentrating on our areas of expertise. These include, but are not limited to, synthesis image processing, low noise receiver systems, and digital signal processing; many of the developments are, in fact, being used or demonstrated on the EVLA. Our long-range technical goals are based on the expansion of observational parameter space, in particular, field of view, shorter millimeter wavelengths, image dynamic range, and high resolution in the time domain. All of this must be accomplished while maintaining or even improving upon the best system temperatures of current receivers.
Cost will continue to be a limiting factor in parameter-space expansion. One way we are addressing this is by simplifying receiver systems and moving the conversion to digital signals as close to the telescope feed as possible. Early digitization will also improve signal integrity, and it will allow some signal processing, such as the conversion from linear to circular polarization, to be moved from expensive waveguide components to digital arithmetic. This is only one example of areas to be featured in the "Lab Notebook" column. Specific topics to be covered in the coming year include phased array feed developments, WIDAR correlator results, ROACH board design and implementation, wide-field imaging algorithms for EVLA, PAPER antenna design, and a hybrid analog/digital sideband-separating mixer