Activinsights GENEActiv Manuale di istruzioni per l'uso - Pagina 16

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iii). Understanding .csv files

The first 100 rows of the .csv file contains all the information about the device, its firmware and the

trial information included upon device configuration. In both the raw data and the epoch compressed

files, the data starts from line 101 and is organised in the following columns.

Column

In the epoch compressed .csv, the gravity-subtracted sum of vector magnitudes is calculated as

follows:

SVM

s = ∑ | (x

For each measurement in the epoch the vector magnitude is created and 1g is subtracted. When

the accelerometer is static and the earth's gravitation pull is the only acceleration, the result of this

will be close to zero.

The total number of measurements in the sum is defined by multiplying the recording frequency by

the epoch length. Measurements from different recording frequencies and epoch lengths can be

compared with suitable scaling.

Raw Data

Time stamp

X axis (g)

Y axis (g)

Z axis (g)

Light level (lux)

Button (1/0)

Temperature (◦C)

)

- 1g |

Epoch Compressed

Time stamp of epoch end

Mean x axis

Mean y axis

Mean z axis

Mean lux

Sum of button press time

Mean temperature

Sum of vector

X axis standard deviation

Y axis standard deviation

Z axis standard deviation

Peak lux