CCD Acquisition with Voodoo

Starting and Configuring Voodoo

Voodoo, the Java GUI for the CCD controller, runs either on emu or galah. The current default (Spring 06) is to run on galah. If you need to change this, remember to switch the fibers from the CCD to the computer you are going to run the controller on.

To start voodoo on emu:

Note that emu must be booted under the "Linux with memory for voodoo" kernel (this choice shows up at reboot time). If you get lots of memory errors, or have to reboot emu for some reason, make sure you choose the correct kernel when rebooting.
  % tcsh  (ie make sure you aren't in a bash shell...)
  % cd /root/system/CCD_Controller/runvoodoo
  % source voodoosetup
  % voodoo &
At this point, the voodoo window will open. An error message will appear saying that the image size larger than buffer. Click Ok. Voodoo will still start normally.

To start voodoo on galah, just click the voodoo icon on the desktop.

In the Camera panel, turn the camera idle on, so that the CCD will flush itself between exposures.

Click the Setup menu button. This will bring up the Controller Setup window. Note that under Master Board, Timing Board should be selected. (If values are not pre-filled, click Load which brings up the Open window, where you can browse for the appropriate setup file, which is what??. Click Open.) Now Click Apply. For each selected button, a message in the main Voodoo window should appear with a "done" reply. Problems are indicated by a red "failed" error message (note that currently one error message is normal). If apply doesn't work:

try it again. and again. and again...
if no success, try clicking the Reset PCI button, then Apply.
if no success, cycle controller power (on the telescope).
if still no success, check for the green light on the PCI card on the computer (in the computer room, where the orange optical fibers plug in). If there's no green light, the CCD and computer aren't talking, and you are in trouble.

Note that the values for the Image dimension should be 2200x4200. The chip has 2048x4096 active pixels; there are 25 extra pixels in front of each amp that get read out first on each line, and because of the way the output is pipelined through the controller 3 pixels are read before anything valid comes out. In future the junk and prescan could be removed prior to the user seeing the data, but a low priority for now. The columns therefore look like this:

  3   +    25    + 1024  +    48          48       1024  +   25        3
junkA + prescanA + dataA + overscanA + overscanB + dataB + prescanB + junkB

Click the Debug menu button, then click "Disable Exposure Timeout". This allows you to pause and resume exposures.

Click the Parameters button. Load debug.par and apply. Then go to the submenus and explicitly apply in each submenu the following:

Readout: double amp (if you forget, the controller will readout through a single amplifier but deinterlace the data as if it were read through two amplifiers. The result is an image where the two halves are mirror images of each other. It also will take 90s to readout instead of 60s).
Temperature: set to -125.
Video Offsets: these set the pedestal level, and change depending on temperature and gain. In a zero, you want the levels to be around 500-1000. As of Spring 06, decent values for the video offsets are 2384, 2462. Note: Raising the video offset lowers the pedestal. DON'T PUT ANY VALUES IN THE DC BIAS CONTROL VOLTAGES on the video offsets page. These change the voltages sent to the CCD by the controller, and could potentially fry the chip.
MPP: Don't use MPP.

Gotchas:

make sure that you enter the data directory with a trailing slash (ie: "Z:/root/Mar2006/"). otherwise voodoo hangs.
if the biasses look screwy, with a high read noise, or a "moire pattern" on them, click on "Setup", then check "Utility Board" (and leave everything else unchecked), and download the utility board file again. After doing this, double check that all modifications you might have made (readout size, video offsets, etc) get reapplied, and also make sure the CCD temp is being regulated.
if parameters dont seem to be loading on startup, .VoodooChild.curse (found in /root/system/CCD_Controller/runvoodoo) may have gotten corrupted. It should look like this. Careful not to edit by hand; just look at this example for the proper parameters. Enter them by hand via the Voodoo setup windows, then hit Program->Global Settings->Save Setup.
if voodoo constantly comes up borked, delete .VoodooChild.curse and enter parameters (via the Voodoo windows) to match the example above.

Processing Images

When the image is read out, you can immediately display it; you'll see a gap in the display because you are reading out of both amps. To make a joined, trimmed up image, you'll want to do the following (in iraf, of course):

chpixtype image.fits image.fits type=ushort
mkmsc image.fits image.fits descrip=2amp.dat
ccdproc image.fits overscan+ trim+ merge+ biassec=!biassec trimsec=!trimsec

Note that the 2amp.dat example file is for 2200x4200 images (the default), and you may want to alter as you see fit.

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