Here is a small description of the sub-menus called :
0-mean: remove the continous componant of a signal (its average becomes NULL)
Band-Pass: Combination of both HIGH and LOW Pass in cascade, it creates a band-pass filter
Example of band-pass [0.02 – 0.1] Hz 4th order
Low-Pass: Classical, but safe, value in filtering : the Butterworth filter of 2*n order (the order must be even)
Example: Low-pass filter 4th order, 0.05 Hz
High-Pass: Butterworth filter of 2*n order, High-Pass
High-pass 0.02 Hz 4th order
Farrer-12-6s: a combination of low-pass and rejectors, giving very steep slope near the cut-off frequency, for removing oceanic noise.
Farrer filter 12-6s 4th order
10%-taper: the generalized Hanning window : a cosine on half a given period.
Trend: For removing trend of a signal with a best fitted polynome of 1 order (it does not introduce dephasage)
Before Trend order 1 filter
After Trend order 1 filter: the very long period trend is removed
Polynomial-trend: removes trend of a signal with a best fitted polynome of n order (without dephasage)
After Trend order 3 filter: the very long period trend is better removed than with order 1
Remove-LTA (Long Time Average): for removing very long period oscillations in a signal (like a smooth high pass)
Same as above, plus remove_LTA filter, this processing remove period with a cut-off period of 1000s
Modulus of transfer function of remove_LTA filter
Natural integrator: the pure mathematical integration, like dividing the the spectrum by jw, but it works also in the time domain
Modulus of transfer function of trapezoidal integrator
Natural derivator: the pure derivation operator (product by jw), in the time domain also, with the Z bilinear transform.
Modulus of transfer function of natural derivator
Integrator Fc: an integrator with a cutt-off frequency, it avoids the amplification of the low frequencies to infinite.
Modulus of transfer function of integrator with 1000s of corner period; notice the fall of modulus close to Nyquist frequency.
Rejector Fc: a stable and simple rejector of 2n order, for removing sharp rai of noise.
Modulus of transfer function of rejector order 4 at 0.1 Hz
PolePedestal : this filter is the inverse of the rejector filter of 2n order, for amplifying sharp rais of signal.
Pole on pedestal filter is the the inverse effect of a rejector : it amplifies a sharp frequency band.
Median filter: a non linear filter for removing stupid individual points (spikes) in a signal. This filter has a non linear response.
Of course, the transfer function cannot be calculated by injecting a Dirac as the input of the filter: It will be removed!
Compensator 1: a filter for compensating instrumental response with order one.
Compensator 2: a filter for compensating instrumental response with order two.
Example of compensator order 2 between 0.1 and 0.02 Hz. Despite of arbitray unit on the vertical scale (Fourier transform of a Dirac of arbitray unit convolved with the desired filter), the gain is exactly 1.0 toward the high frequency limit.
Init Signal : reload the unfiltered signal in the given window.
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