  The radio spectrum is a finite and increasingly precious resource for
astronomical research, as well as for other spectrum users. Keeping the
frequency bands used for radio astronomy as free as possible of unwanted Radio
Frequency Interference (RFI) is crucial. The aim of spectrum management, one of
the tools used towards achieving this goal, includes setting regulatory limits
on RFI levels emitted by other spectrum users into the radio astronomy
frequency bands. This involves discussions with regulatory bodies and other
spectrum users at several levels - national, regional and worldwide. The global
framework for spectrum management is set by the Radio Regulations of the
International Telecommunication Union, which has defined that interference is
detrimental to radio astronomy if it increases the uncertainty of a measurement
by 10%. The Radio Regulations are revised every three to four years, a process
in which four organisations representing the interests of the radio
astronomical community in matters of spectrum management (IUCAF, CORF, CRAF and
RAFCAP) participate actively. The current interests and activities of these
four organisations range from preserving what has been achieved through
regulatory measures, to looking far into the future of high frequency use and
giant radio telescope use.
