DSP-Enabled Radio Astronomy: Towards IIIZW35 Reconquest
Résumé
In radio astronomy, the radio spectrum is used to detect weak emissionfrom celestial sources. By spectral averaging, observation noise isreduced and weak sources can be detected. However, more and moreobservations are polluted by man-made radio frequency interferences(RFI). The impact of these RFIs on power spectral measurement rangesfrom total saturation to subtle distortions of the data. To some extent,elimination of artefacts can be achieved by blanking polluted channelsin real time. With this aim in view, a complete real-time digital systemhas been implemented on a set of FPGA and DSP. The currentfunctionalities of the digital system have high dynamic range of 70 dB,bandwidth selection facilities ranging from 875 kHz to 14 MHz, highspectral resolution through a polyphase filter bank with up to 8192channels with 49 152 coefficients and real-time time-frequency blankingwith a robust threshold detector. This receiver has been used toreobserve the IIIWZ35 astronomical source which has been scrambled by astrong satellite RFI for several years. <P />