Importing Multi-channel Data into a Dataset

Multi-channel data can be stored in any of the basic data formats used by the single channel import (ASCII, 8-bit Byte, 16-bit Integer, IEEE 32-bit Floating Point, or IEEE 64-bit Double Precision). The individual data points can be organized into one of two storage modes: INTERLACED or SEQUENTIAL.


Interlaced data has one point from each series to be imported grouped together, immediately followed by a group containing the next point in each series. Typically, in INTERLACED ASCII data format, each point is delimited by a comma, space(s), or tab, while each group is delimited by a carriage return or line feed; that is, each channel appears in a separate column.


Sequential data has all the points in a series grouped together, followed by all the points in the next series, followed by all the points in the next entire series, etc.. The end of one series and the beginning of the next is determined by the number of samples specified for each series.


Multi-channel ASCII data files usually have one channel per column, but can have also have each sample point on a separate line, or delimited by a comma, space(s), or tab(s). The points in binary data files are not separated by any delimiters; the binary data format indicates how many bytes there are per point. During import, DADiSP reads the file across the rows. Specifying INTERLACED or SEQUENTIAL indicates to which Series the data point belongs. For the purposes of readability, only ASCII files will be used in the examples.




The following example shows an INTERLACED Multi-channel ASCII data file containing five channels. Each channel is arranged in a separate column and each sample point is arranged on a separate line. There are 4 samples per channel shown.


-0.2077 0.1604 1.4404 -0.4000 -1.0220
-1.2166 -0.6520 0.8283 -1.4101 1.0147
-0.9206 -0.7086 -0.4712 -0.3898 -1.5753
1.1046 0.5612 -0.8261 -1.0858 -0.7499 . . . 


The following example shows a SEQUENTIAL Multi-channel ASCII data file. In this example, there are five samples per channel and there are four channels in the file: each channel is arranged in a separate row and each sample point is separated by spaces.


-0.0772 0.7415 -0.7522 1.3899 2.0365
-0.5231 1.3911 -0.8809 -0.2902 0.2984
1.0895 -0.3584 0.7943 -0.4427 -0.8470
2.0392 1.2791 -1.5012 -0.2085 0.1685  


There are two importing options for multi-channel data files. You can import each channel individually by interactively editing the Import Data dialog box, and identifying each channel in the Advanced options. Or, you can import all the channels of interest in one step by creating an import header file and loading it with the Load option. Each of the steps in the import process (for importing channels individually or all at once) are described below, and some multi-channel import examples are included at the end of this section.


Note that DADiSP will attempt to read the information in a data file's header unless you check the Skip Header box in the Advanced Import dialog box, or set IMP_SKIP_HEADER in the dadisp.cnf file to 1. DADiSP only interprets DADiSP keywords in headers.