System Identification

resample

Resample data by interpolation and decimation.

Syntax

zr = resample(z,R)
[zr, R_act] = resample(z,R,filter_order,tol)

Description

z: The data to be resampled, given as an iddata object

zr: The resampled data returned as an iddata object

R: The resampling factor. The new data record will correspond to a new sampling interval of R times the original one. R > 1 thus corresponds to decimation and R < 1 corresponds to interpolation. Any positive real number for R is allowed, but it will be replaced by a rational approximation (R_act).

R_act: The actually achieved resampling factor.

filter_order: The order of the presampling filters used before interpolation and decimation. Default is 8.

tol: The tolerance in the rational approximation of R. Default is 0.1.

Note    To use the resample function, you must have the Signal Processing Toolbox installed.

Caution

For signals that have much energy around the Nyquist frequency (like piece-wise constant inputs), the resampled waveform may look "very different," due to the prefiltering effects. The frequency and information contents for identification is, however, not mishandled.

Example

Resample by a factor 1.5 and compare the signals.

plot(u)
ur = resample(u,1.5);

plot(u,ur)

rbj

resid