DSP enabled radio astronomy in highly corruptive environment

As a result of the development of telecommunications, radio astronomers have to deal with an increasing number of observations polluted by man-made radio frequency interferences (RFI). Current receiver designs, however, which are based on the hypothesis of a non-corruptive environment, are no longer suitable as their performances in terms of linearity and frequency rejection are insufficient to cope with high dynamic RFI. Moreover, their hardware architecture is too specific to allow additional functions to be implemented. In this paper, a new generation of radio astronomic receiver is presented. It has been specifically designed for the single dish telescopes of the Nançay observatory (France). Eight independent channel (14 MHz bandwidth each) are processed by a fully reconfigurable digital unit. This system is based on a HUNT Engineering system (Heron modules and HEPC 9 boards). Its primary function is to provide high resolution dynamic spectra. Depending on the interference context, part of the calculation power can also be used to carry out real time RFI detection in order to clean up the spectra. Hardware upgrade is under progress with a view to implementing a 4096-bin polyphase filter bank and to developing more complex RFI mitigation algorithms.