[FieldTrip] read_biosig_header.m

Steve Deiss sdeiss at ucsd.edu
Thu Jul 12 19:01:14 CEST 2012

Thanks for this note.  Changing the call in read_biosig_header and 
read_biosig_data does make the problem go away, ie., the digital trigger 
channel is not zeroed.  I do not know what other side effects there 
could be.  So I am a little wary.


On 07/11/12 01:20, "Jörn M. Horschig" wrote:
> Dear Steve,
> Although I cannot help you directly and do not know about the specific 
> error you got, you can find all code changes on 
> http://code.google.com/p/fieldtrip/
> For the biosig file you are referring to, please look here:
> http://code.google.com/p/fieldtrip/source/diff?path=/trunk/fileio/private/read_biosig_header.m&format=side&r=5429 
> (but as you can see, nothing changed there)
> Hope someone else can help out (Robert is on vacation right now, so 
> maybe someone else can help)
> Best,
> Jörn
> On 7/10/2012 8:49 PM, Steve Deiss wrote:
>> The fieldtrip version we have calls function 'read_biosig_header' 
>> which calls 'sopen' with the following sequence.
>>      biosig = sopen(filename,'r');
>> For some reason it loses the digital triggers on channel 1 in our 
>> data after issuing the following warning:
>> "Reading data file header...
>> WARNING SOPEN(EDF): Physical Max/Min values of EDF data are not 
>> necessarily defining the dynamic range.
>>    Hence, OVERFLOWDETECTION might not work correctly. See also 
>> EEG2HIST and read
>>    http://dx.doi.org/10.1016/S1388-2457(99)00172-8 (A. Schlgl et al. 
>> Quality Control ... Clin. Neurophysiol. 1999, Dec; 110(12): 2165 - 
>> 2170).
>>    A copy is available here, too: 
>> http://www.dpmi.tugraz.at/schloegl/publications/neurophys1999_2165.pdf "
>> If we let EEGLAB read the data, its function 'pop_biosig' calls 
>> 'sopen' with
>>      biosig = sopen(filename,'r',0,'OVERFLOWDETECTION:OFF');
>> The data read in here includes the triggers so that we can go on to 
>> epoch and process the data.
>> We are not yet ready to upgrade to the very latest fieldtrip.  So I 
>> would like to know if there is an easy way to
>> determine if the latest version of fieldtrip changed anything in the 
>> way sopen is called from read_biosig_header?
>> If it matches what EEGLAB does here, we can match that as a temporary 
>> fix.
>> I'll try to download and unpack it to see, but if this is a known 
>> problem, fixed or not, I'd appreciate any tips.
>> Thanks
>> Steve
>> _______________________________________________
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip

Steve Deiss, M.Sc.
MMIL Lab (Dale and Halgren), UCSD, La Jolla, CA, USA
Neuroimaging Research Associate

More information about the fieldtrip mailing list