KEYWORDS: Device simulation, Telescopes, Control systems, Computer simulations, Electronics, Radio telescopes, Control systems design, Signal detection, Optical instrument design, Receivers
In addition to reliably controlling hardware, a control system should instill confidence by clearly reflecting the user's commands. If the control system of a radio telescope is capable of simulating the effects of the electronics on the RF signal, the user can be provided with practical descriptions of his or her observing configurations. A simulation allows a direct characterization of the RF signal representation rather than a raw list of attenuator, mixer or filter settings. However, because simulation is practical only if it can be kept current and accurate; it must keep pace with both engineering and operational modifications. This is possible if the software interfaces for each telescope device are identical, thus permitting hardware enhancements in the simulation to be implemented as formulated additions rather than as changes. The design of the portable monitor and control system, Ygor, used by the Green Bank Telescope treats each telescope device as an independent unit with identical control interfaces. Differences among devices are reflected by distinct sets of control Parameters. Those Parameter subsets that affect the RF signal representation are passed on to a simulation program which computes basic frequency characteristics throughout the telescope. The signal descriptions are provided to the observers as feedback both in the user interfaces and as part of their data.
KEYWORDS: Telescopes, Control systems, Control systems design, Human-machine interfaces, Receivers, Antennas, Optical instrument design, Interferometers, Radio astronomy, C++
The software designed to monitor and control the Robert C. Byrd Green Bank Telescope (GBT) was generalized into Ygor, an object oriented framework for control system implementation. Ygor is deployed on the GBT on a variety of platforms, together making up the GBT Monitor and Control system. The design of the Ygor system will be presented along with the design philosophy leading to these design decisions. Implementation details and case studies will be used to illustrate the advantages of this system.
A difficulty in writing control software for research telescopes is designing sufficient flexibility to handle continually changing requirements. The primary goal of the control software architecture for NRAO's new 100-meter radio telescope in Green Back, West Virginia is flexibility through the construction of a modular software system. Using the principles of modular design: (i) the number of systems implemented to satisfy the required functionality between users and devices was minimized; (ii) each device was implemented as an autonomous unit; (iii) object-oriented design and C++ were used throughout the system. The purpose of this report is to present the software architecture being used to achieve a modularity in the Green Bank Telescope.
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