Radiotelescope low-rate tracking using dither

The National Radio Astronomy Observatory's Green Bank Telescope, located in West Virginia, is one of the world's two largest articulated radiotelescopes. It has a unique configuration characterized by offset reflector which creates difficulties in precision tracking, especially during tracking at low rates. A high-frequency external signal called a dither is injected into the system. The dither improves the telescope pointing at low tracking rates. The high-frequency dither signal excites local vibrations only causing the breaking of the friction-stiction phenomena. The vibrations are not transmitted through the telescope structure, thus not impacting its pointing performance.