Dear all,
We also use a big Panasonic projector, and all projectors are able to synchronize to higher frequencies (typically up to 85 Hz) but this doesn't change the internal refresh rate which is always 60 Hz. Sending 60 Hz frames is thus the only way to ensure a stable lag.
Introducing any LCD or LED screen in the MSR seems to me very risky, it means also having power line inside. Do not forget that SSS is a spatial filter, and as all filters it has a limited attenuation factor. Elekta people claim a factor of 1000 roughly, depending on the frequency. So I am afraid that the 60 Hz noise (power if US and frame rate) will still be huge in the signal (not to speak of other possible internal frequencies in the display)
Cambridge Research sells a high rate BW projector (http://www.crsltd.com/tools-for-vision-science/)
All the best,
Antoine Ducorps.
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CENIR - Centre de Magnétoencéphalographie
Tél (33) 1 42 16 11 62 (bureau)
(33) 1 42 16 14 10 (MEG)
http://www.cenir.org/
http://cogimage.dsi.cnrs.fr/
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CENIR Plate-forme MEG-EEG
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DepthQ 360 DLP Projector
The DepthQ® 360 is a greyscale DLP projector that outputs luminance frames at 360Hz.
Key technical features:
1280x720 pixels (16:9; 0.55” TI DMD)
Analogue VGA input
Greyscale luminance output only (no colour)
360Hz frame rate
8-bit greyscale resolution
Linear transfer function
2500:1 contrast ratio
Syncs to any graphics card that can produce 1280x720 RGB video @ 120Hz
Le 14 nov. 2012 à 18:47, Maarten van-Casteren a écrit :
>
> Actually, one of the main problems with our current projector
> is the lag: it only shows the input with a delay of two frames,
> which at 60Hz is about 34ms. We would want something that
> is a bit faster. A higher frame rate would also be nice, but the
> main thing is the input lag.
>
> Maarten
>
> -----Original Message-----
> From: Discussion list for international MEG community [mailto:[log in to unmask]] On Behalf Of Tom Holroyd (NIH/NIMH) [E]
> Sent: 14 November 2012 17:45
> To: [log in to unmask]
> Subject: Re: [megcommunity] LCD screen in MEG chamber
>
> We use this Panasonic projector. It goes up to 85 Hz, though we usually run it at 60 Hz.
> It works well.
> http://www.projectorcentral.com/Panasonic-PT-D3500U.htm
>
> You need to buy a non-standard lens to project onto a small screen at a short distance properly, see the "throw distance" calculator:
>
> http://www.projectorcentral.com/Panasonic-PT-D3500U-projection-calculator-pro.htm
>
> Beth wrote:
>> We are hoping to accomplish the same thing here in our MEG. We would like to have refresh rates >75Hz with visual stims sent from Matlab using the Psychtoolbox. This is quite difficult with the standard LCD monitor and our LCD projector. Does anyone have a setup for refresh rates of 85Hz? What type of DLP monitors are being used successfully for MEG vision studies?
>>
>> Beth
>
> --
> The white knight is talking backwards.
