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Bug 594 - yokogawa trigger channels are not correctly detected

Reported 2011-04-22 11:39:00 +0200
Modified 2011-05-05 21:24:30 +0200
Product: FieldTrip
Component: yokogawa
Version: unspecified
Hardware: PC
Operating System: Mac OS
Importance: P1 normal
Assigned to: Robert Oostenveld
Depends on:
See also:

Lesley Sand - 2011-04-22 11:39:24 +0200

[Robert wrote this, using Lesley's bugzilla account]] In the "'R1581 Paisley Acqua run1 11.10.2010.sqd' file the trigger channels are not automatically detected because they have type "null". This can be solved by using the trigindx option in ft_read_event Furthermore, the trigger channels are analog and have noise, causing many triggers to be detected. This can be solved by thresholding the analog trigger value (which seems to be between 5 and 0 volt). The analog trigger channel is "pulled down" from 5 volt to zero, this currently requires both flanks to be detected. Looking at the first sample in the continuous file might tell whether it is 0 or 5 volt.

Robert Oostenveld - 2011-04-22 14:49:20 +0200

I have added the options "threshold", "detectflank" and "trigindx" to ft_read_event and documented them. These are passed on to the low-level read_trigger function. I also implemented the option detectflank=auto in read_trigger. I suggest you use ft_databrowser to identify the channel numbers (1-offset in matlab) for the trigger channels and for the appropriate value of the threshold.

Tilmann Sander-Thommes - 2011-04-26 10:52:57 +0200

Have a look at my reply to bug 494 to learn how to change channel type within the ET MEG160 software. Roberts new additions to ft_read_event are very nice.

Robert Oostenveld - 2011-05-05 21:24:30 +0200

bulk action: closed all bugs with status "resolved/fixed"