Design And Software Aspects For The Control System Of The 30 m MRT

Abstract
The 30 m Millimeter Radiotelescope (MRT) will have a beamwidth of less than 10" when operated at a wavelength of 1.2 mm. It is an open air telescope located on a mountain ridge in southern Spain. There the instrument is exposed to severe environmental influences, especially wind and temperature changes. The pointing and tracking accuracy required is of the order of a few seconds of arc. Simulations have shown that these specifications cannot be met with conventional servo design. An improvement of performance can be obtained applying the modern concept of state control. The state controller needs the acquisition of data about position and velocity at several points of the instrument in real time. Additionally the state controller requires repetition rates of a few milliseconds, in which the data have to be read, converted and the servo algorithms calculated. This is performed by microprocessors operating in CAMAC crates close to the driving system. The whole system is controlled by two identical computers. One usually controls the antenna and data acquisition from the receivers, the other can be used for data analysis or as a backup controller. All receivers are connected via CAMAC, too. Special software tools have been developed for the use of this system. They allow an easy access to the variety of different process control items needed to drive the complete system. They have proved to be a powerful aid in developing the process control hardware and in the installation phase. They will be used for the communication between the operators and the system. In the development of the system the possibility of expanding the system to remote observing has been kept open.

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