User guide

Charnwood Dynamics Ltd. Coda cx1 User Guide – Reference IV-2
CX1 USER GUIDE - COMPLETE.doc 26/04/04 141/162
Data-type Notes
0 Text comments:
This array will be at least 1 byte. The maximum size is not defined.
For converted CODA-3 data files, this may contain some rubbish non-ASCII characters.
1 Date of acquisition:
The date is stored as [day, month, year]. May not be present in some files.
2 3D Marker position:
There is a data array for each marker. Each array contains the marker coordinates for all epochs, scaled by
the resolution (Data type 13). Each epoch is stored as [X, Y, Z].
(X: horizontal, parallel to CODA [+ve left]; Y: horizontal, perpendicular to CODA; Z: vertical [+ve up])
The data must be multiplied by the resolution values stored in Data type 13 (for each marker) to get
coordinate values in µm.
3 Analogue force data:
There are 8 force channels per force plate; there is one data array for each channel.
Acquisition of force-plate data is optional, so this data may not be present.
The data values must be multiplied by the resolution values stored in Data type 17 to get force in Newtons.
If there are no resolution values stored (Version 1 data files), then the resolution is 0.05N.
Force vector components are calculated from the force channel data as follows:
Fx = Force[0] + Force[1].
Fy = Force[2] + Force[3].
Fz = Force[4] + Force[5] + Force[6] + Force[7]
4 Analogue EMG data:
There is one data array for each EMG channel (typically 8); each array stores the raw EMG data for all
epochs, scaled by 0.543 (1.84nV per unit).
5 Marker-in-view flags:
These are bit-arrays - one array for each marker. There is one bit per epoch; the data is padded to a whole
number of uint16 words. The data order within a word is high-bit → low-bit. A bit value of 1 means that the
marker was in view for that epoch. A bit value of 0 means that the marker was out of view (invalid data).
6 Event data:
This is bitwise data, stored in the same way as marker-in-view flags. Not currently used in mpx-30 systems.
7 Sampling rates for Markers:
Currently, the sampling rate is the same for all markers, and in the range 1 - 800Hz for CODA mpx-30 or
cx1 data. For CODA-3 data, the rate is 200Hz.
8 Sampling rate for Force:
There is one value for each group of 8 channels (corresponding to one force plate).
Currently, this will be the same as the sampling rate for markers.
9 Sampling rates for EMG :
Currently, the sampling rate will be the same for all EMG channels, and is 200Hz for CODA-3 data.
10 Sampling rates for Event data:
Currently, the sampling rate will be the same for all Event channels, and is 200Hz for CODA-3 data.
Not present in CODA mpx-30 or cx1 data files. Not used by the current version of the Codamotion Analysis
program.
11 Time scale for Cursor & Bar positions:
This will be the same as the marker sampling rate.
12 Graph Cursor & Bar positions:
These are time-axis positions, stored in left & right pairs. The first pair is for the Left & Right Cursors which
are always present. Subsequent pairs are for each drop-bar displayed on the graphs, if any.
The data must be divided by the values in DataType[11] to get time coordinates in seconds.
13 Marker position resolution (m.resolution):
These are the resolutions of the marker position data (one value for each marker).