fftFilters Module

Erin Carrier Nathan Bowman fftFilters.py Updated: 02/03/13

Library of frequency filters for the results of the FFT.

fftFilters.bandpass(transformed, samplingFreq, cutoffLow, cutoffHigh)

Performs bandpass filtering on result of fourier transform.

Any frequencies not between cutoffLow and cutoffHigh are removed. This is done by setting the coefficients of these frequencies to zero. Sampling frequency and cutoff frequencies must have same units (e.g. Hz).

Parameters:

• transformed – transformed signal
• samplingFreq (double) – sampling frequency
• cutoffLow (double) – low cutoff frequency
• cutoffHigh (double) – high cutoff frequency

Returns:

thresholded transformed signal

Return type:

numpy array

fftFilters.highpass(transformed, samplingFreq, cutoff)

Performs highpass filtering on result of fourier transform.

Any frequencies less than the cutoff frequency are removed. This is done by setting the coefficients of these frequencies to zero. Sampling frequency and cutoff frequency must have same units.

Parameters:

• transformed – transformed signal
• samplingFreq (double) – sampling frequency
• cutoff (double) – cutoff frequency

Returns:

thresholded transformed signal

Return type:

numpy array

fftFilters.lowpass(transformed, samplingFreq, cutoff)

Performs lowpass filtering on result of fourier transform.

Any frequencies greater than the cutoff frequency are removed. This is done by setting the coefficients of these frequencies to zero. Sampling frequency and cutoff frequency must have same units (e.g Hz).

Parameters:

• transformed – transformed signal
• samplingFreq (double) – sampling frequency
• cutoff (double) – cutoff frequency

Returns:

thresholded transformed signal

Return type:

numpy array