data.lowpass
data.lowpass applies a digital filter to data. This is generally a single pole low pass filter.
Command Line Usage
data.lowpass [--t=3] [--a=1,2...] [--b=1,2...] [--gap=1860] [--nocut] [variables]
Arguments
variables
A list of variables (as regular expressions) to apply the filter to. The default is all variables that have decimal (not strictly integer) values and are no flags.
--t=3
Set the filter to a single pole low pass digital filter with the given “time constant”. The time constant is the number of points for the filter to reach ~67% of the final value after a step change.
The default is a filter with a time constant of three.
--a=1,2...
Set the “A” constants for a general digital filter. These are the coefficients applied to the unsmoothed data, with the most recent first.
--b=1,2...
Set the “B” constants for a general digital filter. These are the coefficients applied to the smoothed data values, with the most recent (the prior point) first.
--gap=1860
Set the gap detection threshold in seconds. If there is a gap between points longer than this value the filter is reset.
--nocut
Disable separate smoothers for each cut size.
Example Usage
A single pole low pass filter with a time constant of three
data.get bnd S11a 2010:1 2010:2 | data.lowpass
A single pole low pass filter with a time constant of five
data.get bnd S11a 2010:1 2010:2 | data.lowpass
A one pole, four pass digital filter
data.get bnd S11a 2010:1 2010:2 | data.lowpass --a=0.191534592419177 --b="1.353805290698;-0.687295786920706;0.155077445434616;-0.013121541631082"