LOFAR: the first of a new generation of radio telescopes

The Low Frequency Array (LOFAR) opens a previously largely unexplored frequency domain for challenging radio-astronomical research. At the 10 to 240 MHz operating frequencies of this radio telescope, it is feasible to employ very large numbers of simple, all-sky antennas with wide-band early digitization. This means that almost the full signal processing chain can be realized in (embedded) software. This approach makes it possible to deal with Earth-based radio signals in effective and novel ways. The signal processing challenges in LOFAR are manifold, since the ultimate dynamic range in astronomical images depends on the quality of the full chain of operations that combines ten-thousands of antenna signals into a single multichannel image cube, while correcting for a large variety of instrumental and environmental effects.