| T O P I C R E V I E W |
| weissman |
Posted - Apr 10 2003 : 1:28:04 PM
The projector inside the 1.5 T sometimes "scrolls" images that appear on Donders quite well. That is, the image inside the projector appears to move up and down the screen and, occassionally, is otherwise distorted. Typically, this problem occurs at the start of a scan, and we just restart the scan until the screen displays correctly. However, in my last study the problem became worse, and it was necessary to restart the scans several times during single sessions. I am aware that other experimenters like Mike Nelson at the CCN have also experienced this problem. Is there some way to fix it?
Daniel |
| 5 L A T E S T R E P L I E S (Newest First) |
| jim.voyvodic |
Posted - Nov 23 2004 : 12:31:07 PM
We tested the projector on the 1.5T and couldn't reproduce the scrolling problem. We will need help creating the problem in order to find a solution. Is this a paradigm that has worked and now suddenly stopped working for no reason? What are the video settings?
What software and stimulus files, etc.?
There was a problem with scrolling before, but only at low screen resolution. The hardware doesn't support every video configuration
so if you are changing screen settings maybe that's the problem. If not, we will need to find a time that you can demonstrate the problem.
Have other people experienced any video problems on the 1.5T?
Jim
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| merrill |
Posted - Nov 22 2004 : 10:07:11 AM
I am resurrecting this year-old discussion because we just began a new study on the 1.5 T using Presentation, and so far it has been horrible. We have had to re-start the experiment at least 3 (and as many as 9) times during a session due to the scrolling problem. Our last subject ran over by 30 minutes because of this problem, which should not be happening. This has led to frustration for the experimenter, subjects, tech, and the people who want to use the scanner after us. Although we have been able to "complete" the sessions so far, I have major concerns about the quality of the data we have collected thus far.
We are at a loss as to what to do at this point. Clearly, we cannot continue re-starting over and over and compromising the quality of our data.
Can anyone help us?? |
| weissman |
Posted - Jul 15 2003 : 5:02:49 PM
Dear All,
We are now running on MACH and have still experienced a screen scrolling problem inside the scanner that does not occur on the MACH screen. We changed the refresh rate to 75 Hz from 60 Hz as Jim Voyvadic suggested but that hasn't quite solved the problem. We'll try 85 Hz and see if that helps.
Daniel Weissman |
| weissman |
Posted - Jul 13 2003 : 4:16:13 PM
Hi All,
We had a return of screen "scrolling" at the 1.5 T on Friday for a single run. Hopefully, moving to MACH will improve the situation since we'll be able to change the screen refresh rate from 60 Hz to 75 Hz.
Daniel
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| weissman |
Posted - Jul 10 2003 : 4:04:15 PM
Hi All,
I'd like to thank Jim Voyvadic for helping me with the screen problems I've been having at the 1.5 T. Jim suggested that we change the bit resolution on Presentation to 8 bits from 16 bits, at least when running with a screen resolution of 800 by 600. Today, we ran two subjects using the 8-bit setting and there were no screen problems.
I'll let you know if any problems re-appear, but I just wanted to really thank Jim for all the help he gave us.
Daniel |
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