Hello there, I have a question regarding the CMSIS DSP library function arm_fir_decimate_X.
So for example if I have an ADC which is sampling at 5250 kHz and I want to create a filter using the decimate function, do I have to run the sampled signal through a low pass filter first in order to use the decimate function? The reason why I am asking is because on the description it says "When decimating by a factor of M, the signal should be prefiltered by a lowpass filter with a normalized cutoff frequency of 1/M in order to prevent aliasing distortion. The user of the function is responsible for providing the filter coefficients."
M
1/M
So if I don't missunderstand it, for example I have an ADC which has a sampling rate of 5250 kHz and I want to decimate that signal down by M = 10, I will have to run the signal through a lowpass filter with the cut-off frequency of 525 kHz first before I put it into the decimator function which I then use to filter a for example a 60kHz signal?
If we already know that the input does not have frequency components above half the new sampling frequency: