Radio Frequency Interference
Being a radio telescope, and extremely sensitive radio receiver,
sources of interference are a real issue. The rather isolated
location helps greatly, but the number of electronic devices
generating interference is proliferating, especially at the
signal levels involved. A sign at the entrance asks visitors
to turn off mobile phones and video cameras. I suspect digital
still cameras will be added to that list too.
This structure is used to detect nearby radio sources to allow
the telescope operators to discount them from their observations.
Details of its operations are shown below from the CSIRO display
board alongside the cabin.