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Re: Accuracy of timestamping streamed data

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Re: Accuracy of timestamping streamed data

Subject: Re: Accuracy of timestamping streamed data
From: Hank Heijink <email@hidden>
Date: Tue, 26 Sep 2006 12:17:14 -0400

Thanks very much for your (and everyone else's) comments! That really helped me.

Let the tablet drive the timing. Create a high priority thread that calls read(). Don't use non-blocking I/O and select(), just let read () block. Call mach_absolute_time() right after read() returns. Then send the MVCoordinate to the main thread using performSelectorOnMainThread:

Having done that, it seems there's still anti-aliasing going on - I get 4 to 6 samples around 6 ms apart and then 2 samples around 6.6 ms. See the graphs I put on my website:

http://www.hankheijink.com/Graph.png and http://www.hankheijink.com/ Graph_detail.png

I've been trying to understand where it comes from, but I'm stuck... any ideas?

Thanks a lot,
Hank

Hank Heijink
Postdoctoral Research Fellow
Center for Neurobiology and Behavior
Columbia University Medical Center

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References:  
  >Accuracy of timestamping streamed data (code included - long) (From: Hank Heijink <email@hidden>)
  >Re: Accuracy of timestamping streamed data (code included - long) (From: Jakob Olesen <email@hidden>)




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