EXAMPLES
DIGITAL FILTERING
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Example for
digital filtering

 

In the following example, the raw data of the wind speeds at all heights (Fig.1) have been filtered with a low-pass filter (Fig.2) and with a band-pass filter (Fig.3).

The low-pass filter has a cut-off period (50% energy pass) of 4 hours and thus filters out all high-frequency signals (turbulence, gusts of wind) from the data (Fig.2).

The band-pass filter has a lower cut-off period of 18 hours and an upper cut-off period of 36 hours and thus yields in the main only the signal of the daily variability yet (Fig.3).

 

Fig.1:
Raw data of wind speed.
Fig.2:
Digital filtered data of wind speed. Low-pass filter, cut-off period 4 hours.
Fig.3:
Digital filtered data of wind speed. Band-pass filter, lower cut-off period 18 hours, upper cut-off period 36 hours. The filter response yields the signal of the daily variability around the mean.
© WIND DATA SUiTE - Dr. Helmut Frey      Last modified: 2018-09-19