What will be the frequency ranges of 200hz EEG signal after dwt?

Question

I have 200 Hz EEG signal.I have applied a bandpass filter with a cutoff frequenct 1 to 60 Hz. If now I apply discret wavelet transform for 5 level decomposition .... How the signal will be decomposed??starting from 60 Hz or 200Hz?? Thanks in advance

Answer 1

Welcome to SO.

First of all, I think that the DSP Stack Exchange may be better suited to get help on this topic.

I suspect that you get mixed up between sampling rate (200Hz) and cutoff frequencies (1Hz-60Hz).

• Your ECG data are sampled at 200Hz, or 200 samples per second (SPS). This is the sampling rate.
• Based on Nyquist's theorem, the highest frequency contained in this signal is 100Hz. This is the frequency content of your signal.
• When you apply a band-pass filter to your data, you reject frequencies outside of the 1Hz-60Hz range, but your signal is still sampled at 200SPS.

So what you feed into your 5-level decomposition is a 200Hz sampled time series, whose frequency content has been band-passed between 1 and 60Hz.

I suggest that you plot the spectrum of your ECG before and after band-pass filtering to better understand what is going on.