South African SKA demonstrator systems: Evolving RFI mitigation investigations

The South African SKA demonstrator is founded on the Karoo Array Telescope (KAT). A holistic approach to radio frequency interference (RFI) mitigation has been adopted from the outset. We describe our group's contribution to this evolving effort. We consider the RFI beginning from the 100 km powerlines, through to the site base equipment and continue right up to the KAT-7 telescopes. A site survey was conducted with systems initially deactivated and then individually switched on to determine signature characteristics. More detailed studies include analysis of telescope pedestal shielding interfaces and cable transfer impedance.