Phase Switch

A phase switch is a device used to increase the discrimination and sensitivity of an interferometer, especially at radio frequencies; an extra half-wave path difference is switched in, at well defined frequency, between the two interfering signal sources. In-phase signals then become out of phase and vice versa, so that the signal output becomes modulated by the switching frequency, and can be more easily filtered from the internally generated noise. (The discrimination is highest for sources which are small compared with the interferometer-fringe spacing)

Its use in radio astronomy is generally credited to Martin Ryle, and used extensively in the 1C radio survey.

Famous quotes containing the words switch and/or phase:

    Children ... after a certain age do not welcome parental advice. Occasionally, they may listen to another adult, which is why perhaps people should switch children with their neighbors and friends for a while in the teen years!
    Marian Wright Edelman (20th century)

    The Indians feel that each stage is crucial and that the child should be allowed to dwell in each for the appropriate period of time so that every aspect of his being can evolve, just as a plant evolves in the proper time and sequence of the seasons. Otherwise, the child never has a chance to master himself in any one phase of his life.
    Alan Quetone (20th century)