# Where can I find more information about this formula relating a window's time and frequency size?

I remember having seen a formula of the form

$C=\frac{B}{L}$

that relates a duration $L$(s) of a window to its width $C$(Hz) in the spectrum (defined at -3dB or so). The constant $B$ would be tabulated in function of different windows.

Does anyone know how this formula is called or where I can find more information about it? I searched on Google (Scholar) but dit not find it.

• It's more common to see the bandwidth-time product instead of the ratio – Marcus Müller Dec 20 '16 at 16:43