Tukukkk

I have been trying to downsample a signal, but I'm not sure if I have the proper command? can you give me the proper command with a brief explanation?

Depending on what you are trying to achieve, the downsample can be enough.

Example code:

pkg load signal % To download the signal package

x = cos(1:1000); % Create a signal

y = downsample(x, 2);

However, it will not apply a low-pass filter so it can introduce unwanted aliasing effects on your signal. Like the command help downsample says:

For most signals you will want to use decimate instead since it prefilters the high frequency components of the signal and avoids aliasing effects.

Now if you want to downsample and apply the low-pass filter, you would like to use decimate but it only works for a downsampling with an integer factor, for example from 96kHz to 48kHz, you decimate by a factor 2. From help decimate

Note that Q must be an integer for this rate change method.

Example code:

pkg load signal % To download the signal package

x = cos(1:1000); % Create a signal

y = decimate(x, 2);

Finally, if you want to downsample by a rational number, for example by a factor of 2/3, from 96kHz to 64kHz, you will need resample like it was suggested by other users.

pkg load signal % To download the signal package

x = cos(1:1000); % Create a signal

y = resample(x, 2, 3);

Note that you can still use resample to downsample by an integer factor, for example y = resample(x, 1, 2); but it slower that decimate.

e.g.

y=resample(x,L,M);

.

.

x--> your signal

L--> increase sampling rate

M--> reduce sampling rate