MATLAB: Downsample

downsample

is there a matlab command that will filter and downsample data?

Best Answer

There are several possibilities. You can use either upfirdn or design the filter using fdesign.decimator and then filter your signal.

doc upfirdn
doc fdesign.decimator

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MATLAB: Fir and iir filtering

You have to know your filter specifications. If you do, you can do both with fdesign.lowpass and fdesign.highpass

fdesign.lowpass and fdesign.highpass have different specification strings which support different filter designs.

The default string 'Fp,Fst,Ap,Ast' supports both FIR and IIR designs.

Here is an example:

Design a lowpass filter with a passband frequency of 1 kHz, a stopband frequency of 1.5 kHz, passband ripple of 0.5 dB, and stopband attenuation of 40 dB. The sampling frequency is 20 kHz

   d = fdesign.lowpass('Fp,Fst,Ap,Ast',1e3,1.5e3,0.5,40,20e3);
   designmethods(d)  %shows which designs are valid for this spec
   Hdeq = design(d,'equiripple'); % FIR filter
   Hbutt = design(d,'butter'); %IIR design

MATLAB: FFT of Downsampled Signal

Hi Adam,

If you have significant noise on the signal, then decimate(x,10) or resample(x,1,10) would be preferable. Your resulting sample rate is as you have indicated (312.5 kHz).

I would take a spectrogram on the resulting signal to see how the frequency content changes over time.

Hope this helps!

-Greg

Best Answer

Related Solutions

MATLAB: Fir and iir filtering

MATLAB: FFT of Downsampled Signal

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