Marker analysis

Performing a marker analysis

After opening a raw file for a marker analysis, ANSLAB offers 3 types of marker analysis to choose from (binary, digital, and fixed):

• Binary
  This analysis type is used to create timing files based one or more binary channels.
• Digital
  Use this analysis mode if a single marker channel, consisting of distinct integer values only, should be analyzed.
• Fixed
  Allows to create simple timing files with either a fixed number of segments or a fixed segment length (the other parameter is determined based on the recording length).

In the following the different analysis modes are described in more detail.

Binary timing

If you have only one dedicated binary marker channel, ANSLAB can load it automatically and extract timing information without further input.

In all other cases, for instance if you wish to use several binary marker channels as digits of a binary number, select manual channel selection, enter the number of channels to load, enter the sampling rate to operate with, and choose the channels from a list of available channels.

Important: values in the involved channels equal to or below 0 are treated as binary zeros. All other values are interpreted as binary ones.

Next, if more than one channel has been chosen, the combination operation must be chosen (i.e. how the binary channels should be combined):

Important: in case the single channels define binary digits, the n-th channel is used to construct bit n-1. It is therefore important to load the channels in the right order (i.e. starting with the least significant bit).

Next you can enter a minimum event duration and a maximum event duration. Event durations are measured from beginning of a new marker value to the next value change. Choosing '0' and 'inf' for minimum and maximum duration will cause ANSLAB to write one timing segment for every marker value change found in the (combined) marker signal.

The following dialog allows to specify special event numbers to extract and special event numbers to ignore. These options allow creating timing files only containing events of interest for a specific analysis type. Choosing 'all' and 'none' for events to extract and events to ignore will cause ANSLAB to write one timing segment for every marker value change found in the (combined) marker signal.

After this, data is loaded, resampled and analyzed. If the timing file to be written already exists, ANSLAB allows to overwrite that file or add the newly extract timing information as a new timing field to the extisting timing file. ANSLAB allows to immediately view the created m-file in the MATLAB editor.

Digital timing

The procedure for a digital marker analysis is identical to a binary marker analysis. However, other operations to combine multiple marker channels are available (add, subtract, logical and, and logical or).

Fixed timing

This analysis type allows to create a fixed number of non-overlapping segments covering the complete raw data (the length of the segments is determined automatically based on the recording length; option 'absolute'). It is also possible to specify a fixed length for the segments to be created. The number of non-overlapping segments is then determined automatically (option 'relative to filelength'):

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Batch processing

The most comfortable way to create timing files for many raw files is to carry out the marker analysis in batch mode. For this it must be ensured that the marker analysis options are set correctly.

Once the marker analysis options have been adjusted and the channel naming options contain all needed marker channel names, loading a batch file and running the marker batch analysis creates the timing files for all raw files in a batch.

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