Spectrum control procedures for the national radio astronomy observatory

The Green Bank site for the National Radio Astronomy Observatory (NRAO) and the Sugar Grove site for the Naval Radio Research Laboratory (NRRL) were located fairly close together with the hope that both could share in the locally relatively low radio noise environment that existed when the installations were first built. The procederes which have been followed to maintain, as far as possible, the scientific value of this environment are described, and some examples of the degree to which this effort is succeeding are given. Similar problems will arise at the site chosen for the very large array (VLA) in New Mexico and these are discussed briefly.