fft_clean()

Jump to bottom Edit New page

jamesjun edited this page Oct 31, 2017 · 7 revisions

Adaptive notch filter which cleans narrow-band noise peaks that exceeds the threshold (P.fft_thresh).

The operation is skipped if P.fft_thresh==0.

Syntax

mr1 = fft_clean(mr, thresh, nbins) ** mr1: Traces to clean up (nSamples x nSites: single) ** thresh: P.fft_thresh expressed in MAD unit
** nbins: Number of frequency bins to perform normalization

Operation

Time-domain signal is converted to the frequency domain (FFT)
Average power across channels are computed.
Power is detrended using 1/f relationship in freq vs. power.
power-frequency product is normalized by the MAD for each frequency bin.
Frequency-power product exceeding the threshold (P.fft_thresh) are set to 0.
Cleaned signal is transformed back to the time-domain signal (IFFT).