Difference between revisions of "ASCII File Format"

Revision as of 15:41, 15 February 2017

BESA Research can read 2 types of ASCII file formats to import data. These are identified by different extensions:

• ASCII vectorized file format (*.avr)
• ASCII Multiplexed file format (*.mul)

ASCII Vectorized file format

The ASCII vectorized file format stores data of one channel (all time points) per line. It is defined as follows: The first of two header lines contains the following data descriptors:

• Npts = number of sampled points in each channel
• TSB = time sweep begin [ms]. Time of first data point relative to zero of epoch
• DI = digitization or sampling interval [ms]
• SB = scaling bins/microvolt in file = number corresponding to 1 microvolt
• SC = scaling calibration, used for setting magnitude of display in BESA
• Nchan = number of channels
• SegmentName = An optional label describing the data.

The second line of the header contains a label for each channel. Each of the subsequent Nchan lines of the file contains values for all Npts time points in floating point or scientific format.

Example

   Npts= 256   TSB= 0.000 DI= 4.000000 SB= 1.000 SC= 200.0 Nchan= 27 SegmentName= Segment1
   O1 Oz P3 T5 T3 C3 F7 F3 Fp1 Fz Cz Pz Fp2 F4 F8 C4 T4 T6 P4 Fpz O2 M2 M1 F10 F9 T10 T9

ASCII Multiplexed file format

The ASCII multiplexed file format stores data of one time point (all channels) per line. It is defined as follows: The first of two header lines contains similar information to that of the ASCII vectorized file:

• TimePoints
• Channels
• BeginSweep[ms]
• SamplingInterval[ms]
• Bins/uV
• SegmentName

Note that the item 'SegmentName' is missing if no segment comment is specified when writing a segment to file. If an epoch of a continuous EEG is exported in ASCII multiplexed format, the first header line contains the additional item 'Time', which indicates the daytime of the first sample in the exported segment. The second line of the header contains labels for each channel, which may be either the original channel names, or the names of the channels of the current montage. Each subsequent line contains values for all 'Channels' at one time point, in floating point or scientific format. Values are given for the current or the original montage, selected as described above.

Labels for source montages have the following form: 'TAr-L'.

• The first two letters indicate the head region: FL=fronto-lateral, FP=fronto-polar, TA=temporal-anterior, TP=temporal-posterior, TB=temporal-basal, OL=occipito-lateral, OC=occipito-central, PC=posterior-central, CL=centro-lateral, CC=central
• The small letter indicates in part the orientation: r=radial, t=tangential, and in part the relative location of the basal temporal source: l=lateral, m=mesial.
• The final letter after the hyphen indicates: L=left, M=middle, R=right.

Example

   TimePoints= 512 Channels= 27 BeginSweep[ms]= 0.00 SamplingInterval[ms]= 5.000 Bins/uV= 1.000 Time=22:02:53 SegmentName=Segment1
   O1 Oz P3 T5 T3 C3 F7 F3 Fp1 Fz Cz Pz Fp2 F4 F8 C4 T4 T6 P4 Fpz O2 M2 M1 F10 F9 T10 T9