The Use of RF Signal Simulation in a Radio Telescope Control System

Mark H. Clarka National Radio Astronomy Observatory, Green Bank, WV 24944-0002, USA

Abstract:

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.

telescope control, simulation, software, user-interface