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Discovery Channel Telescope – Technical Information

Technical

Overview of Control System

The DCT control system handles the complex interaction and distribution of information between the telescope's users and subsystems. Software is a vital element of this control system and must support the needs of telescope operators, guider and wavefront sensor operators, scientists, engineers, and system managers. The system architecture is comprised of a number of subsystem components:

Observatory Control System (OCS): The OCS provides overall system monitoring and control and coordinates high-level functions involving multiple subsystems, including system initialization and shutdown.

Telescope Control System (TCS): The TCS generates time-stamped position and velocity demands for the mount and rotator axes to position a celestial target accurately at a point in an image plane.

Dome Control System (DCS): The DCS controls the dome azimuth and shutter drives.

Mount Control System (MCS): The MCS controls the motion of the mount by translating TCS-generated position and velocity demands into azimuth, elevation, and rotator drive commands.

Active Optics System (AOS): The AOS controls image quality based on look-up tables tied to mount elevation and the mount temperature (open-loop) and optionally also on wavefront data feedback (closed-loop). The AOS controls the precise figure and shape of the primary mirror to ensure optimal image quality. It also controls the secondary mirror tip, tilt, and piston.

Environment Control System (ECS): The ECS monitors and controls a number of elements related to the physical environment and the telescope facility. Specifically, the ECS maintains the telescope chamber temperature at or near the outside ambient temperature by controlling ventilation fans and doors. The ECS also sends ambient temperature information to the instrument chiller and monitors the supply and return chiller temperatures. Additionally, the ECS measures temperature sensors on the primary mirror and provides on/off control of the primary mirror cold plate.

Instrument Control System (ICS): The ICS configures and controls telescope instruments as well as gathers, processes, stores, and transmits detector data from the instruments along with system data.

Guider Control System (GCS): The GCS measures guide target positions and reports any deviation from the expected guide target position from the TCS.

Wavefront Sensor (WFS): The WFS images a demanded target and determines and reports the corresponding wavefront data.

Atmospheric Dispersion Corrector System (ADC): The ADC, based on a dispersion correction requirement from the TCS, calculates the required element positions for the ADC and drives the ADC to this position. The ADC determines and reports any resulting optical deviations to the TCS.


To view a diagram of the DCT control system software architecture CLICK HERE.

For further information on the systems design and components that comprise the DCT control system, download "DCT Software Architectural Design" [1.82 MB PDF].


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