The Kaiser, or Kaiser-Bessel, window is a simple approximation of the DPSS
window using Bessel functions, discovered by James Kaiser.
besselI(0, Beta * sqrt(1-(2*x/m)^2))
k(x) = -------------------------------------, -m/2 <= x <= m/2
besselO(0, Beta)
The variable parameter \(\beta\) determines the trade-off between main lobe
width and side lobe levels of the spectral leakage pattern. Increasing
\(\beta\) widens the main lobe and decreases the amplitude of the side
lobes (i.e., increases the attenuation).