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Re: data resampling

Dear Juan Wu

'downsample' does not take care of aliasing, you would have to apply an anti-aliasing filter yourself beforehand, to make it work properly.
'resample' should be just fine (for integer resampling factors you could also use 'decimate').


Am 14.08.2014 01:05, schrieb Juan Wu:
List experts,

I am attempting to down sample my data from 300 Hz to 1 Hz. I just tried two functions of Matlab: 1) a = resample(Data,1,300); 2) b = downsample(Data,300). The results are quite different between each others.

          image 2

Apparently, the result from "downsampled" is close to the the original data. However, quite a few persons suggested using the re-sampling method - I get this information from google searching, and very agree with this view. Personally I think the downsample method is too simple and very arbitrary. I also do not believe the "Nearest Neighbor" method. I assume that the method resampling takes both "FIR interpolator and decimator" implementation - this is what I expected. Am I right?  But now my output from the re-sampling method is really very terrible. So I assume that the resample function from Matlab does not do a good job for this. I am not sure whether I need change to use other softwares or try other functions in the Matlab. 

Any opinions or references are much appreciated.

Dr. rer. nat. Alexander Lindau

Research associate
SEACEN research unit

TU Berlin - Audio Communication Group
Einsteinufer 17c
D-10587 Berlin

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