There really is no need for a stability factor, unless you are running
itype=8 which takes the derivative right at the source point, R=0.
With all other itype values, you can set stab=0. The derivative
operator used in lamb is a bilinear transform realization of
the derivative with respect to time. In terms of
the Z-transform,
|
(45) |
where Y(z) is the output signal Z-transform, and X(z) is the input
signal Z-transform. The stab factor nudges the pole at the
Nyquist frequency slightly off the unit circle to prevent extreme
blow up of any Nyquist amplitudes in the input signal. The derivative
is realized by an ARMA operator. The formula which realizes equation
(45) is
|
(46) |
where is the j-th sample corresponding to the temporal derivative
of , the j-th sample of the input signal being differentiated.
pm
2018-04-08