New instrumentation for EMC work in radio astronomy

Both conventional swept frequency spectrum analyser based instrumentation and dedicated integrating spectrometers, based on high sample rate DSP, continue to serve admirably in helping to characterize and maintain the integrity of the radio spectrum quality at current radio astronomy facilities. Increasingly, impulsive, often sporadic transmissions are becoming the interference of most importance. Monitoring of both impulsive and continuous interference is important for ensuring the quality of observatory spectrum and also provides a critical role in determining the RF and DSP signal processing dynamic range headroom requirements for new radio astronomy receiver designs. The only way to ensure 100% probability of intercept (POI) is to ensure entire RF bands are sampled at the Nyquist rate. Our equipment uses a remote wideband 0dBi non-directional antenna isolated several hundred metres from the DSP to minimise self interference and maximize sensitivity. The antenna is connected by a high dynamic range RF over single-mode fibre. This paper summarises the CSIRO developed DSP based RFI monitoring system capable of real time nanosecond timescale transient event capture, combined with traditional integrating spectrometer spectrum capture.