TELESCOPE OPERATIONS

The following procedures are used to operate and troubleshoot the GBT Active Surface.

This procedure consists of tasks associated with the operation of the GBT Active Surface and includes:

• Setting the Active Surface state depending on the receiver used.

• Starting the showSurface GUI

• Controlling the Active Surface Servo via showSurface

Unless the active surface is out of service, we are observing at Prime Focus, or are told otherwise, the Active Surface Manager and servo power should be left ON.

In the following procedures, the character ^ is used below to emphasize spaces between dialog elements.

Active Surface Setup for Prime Focus Observing

Active Surface Setup for L to S Band Observing

Active Surface Setup for C Band or Higher Observing

Active Surface Setup for PTCS Testing

Checking Active Surface Servo Power Via Telnet

The showSurface GUI

The following is an example of a "showSurface" window that shows a healthy Active Surface status:

Actuator Status Red = Faulty Actuator Green = Operational Actuator Yellow = Moving Actuator

The GUI updates its information, by default, every 15 seconds. To change the update rate, move the slide bar at the bottom right-hand side of the GUI. The maximum update rate is 5 seconds. You can press the "Update" button at the bottom right-hand side of the screen to manually induce an update.

The green dots on the surface representation indicate a working actuator. Red dots indicate a disabled actuator. Yellow dots indicate a moving actuator. In daily operation, there will be some red dots. The Active Surface can still function with disabled actuators as long as those disabled actuators are scattered fairly randomly around the dish. A concentration of red dots may impede observing and indicates a systemic problem (e.g. blown fuse or faulty control module). As you move the cursor over the dots that represent the actuators, each actuator's rib and hoop location is displayed as well as the intelligent i/o processor (IIOP) and control module (LVDT and Channel) to which it is connected.

A green dot by "Connected" (located on the mid-right-hand side of the GUI) indicates that the GUI is connected to the Active Surface Servo. If this dot is red, then do not trust any information displayed on this GUI.

A green dot by "Sys Ready" (located next to "Connected") indicates that the Active Surface Servo is able to be commanded. If this dot is red, the system will ignore incoming commands to move. Also if this dot is red, you can click on the "Entire Surface" button at the bottom of the GUI to find the cause of the system ready error. See the section labeled "Controlling the Active Surface Servo via showSurface" for more information.

Controlling the Active Surface Servo via showSurface

To monitor and command system-wide aspects of the Active Surface, click on the Entire Surface button at the bottom of showSurface.

Control functionality for the Active Surface Servo is buried in two types of windows in showSurface. One type of window, of which there is only one instance, is the "Command All" window. This window controls system level aspects of the Active Surface. The following is an example of a "Command All" window with a healthy status.

Desired Position To command all actuators to a common position, enter a position (in microns) in the text box and click on the Move button.

Reset This button performs a soft reset of the Active Surface Servo.

Standby Level The "Standby" button is currently not implemented. However, the "Standby Level" text field indicates the general health of the system. A breakdown of standby levels is as follows: 0 = system completely ready to go, 1 = all supplies on, all actuators software disabled, 2 = motor supplies off, everything else on, 3 = motor and transnet supplies off, computer rack on.

Stop This button stops all actuators that are currently moving.

Dismiss This button closes the "Command All" window.

Display/Hide This button toggles the display/hiding of power supply, computer, intelligent i/o processor, etc. details. Click on "Display" to display and "Hide" to hide.

MPS/TPS These dots represent the health of the 20 motor supplies (MPS) which supply power to the actuator motors and 4 transnet supplies (TPS), which supply power to the control modules and i/o processors. Green is healthy. Red is faulty.

GBTAS These dots represent the health of the control computers for the Active Surface Servo. Green is healthy. Red is faulty.

IIOP These dots represent the health of the intelligent i/o processors. Green is healthy. Red is faulty.

The other dots follow the same green = healthy and red = faulty pattern and indicate the status of various components located in the Active Surface Servo room.

Note that the GUI updates its information at the same rate as the main showSurface window.

Commanding Individual Actuators

To command individual actuators, click on the dot associated with the desired actuator on the showSurface panel. A "Command One" window will appear. The following is an example of a "Command One" window with a healthy status.

Rib/Hoop Location of the actuator on the dish.

IIOP/LVDT/Channel Location of the actuator in the Actuator Control Room.

Current Position Current position of the actuator in microns.

Desired Position Allows the entry of a new position (in microns) to move to.

Status / Enabled A green dot by Status indicates that the Active Surface is healthy; red indicates ill health. A green dot by Enabled indicates that the actuator is enabled in software and can be moved; red indicates that the actuator is disabled in software and cannot be moved.

Reset Pressing this button produces a soft reset on the specified actuator.

Disable / Enable Pressing this button toggles the enabled state of the specified actuator.

Move / Stop The Move button moves the actuator to the Desired Position. The Stop button stops the movement of the specified actuator.

Dismiss This button closes the "Command One" window.

Display/Hide This button toggles the hiding of power supply, computer, intelligent i/o processor, etc. details.

Update The "Command One" window updates its information, by default, every 15 seconds. To change the update rate, move the slide bar at the bottom of the window. The maximum update rate is 5 seconds. You can press the "Update" button at the bottom of the window to manually induce an update.

The other status bits indicate extended engineering diagnostic information.

-- DavidRose - 6 Feb 2008