Decay rate of Filter and how it relates to transmission speed
Decay time depends on the dynamic range of decay to be measured.  Normally 90 to 10% rise or fall time, t is related to f -3dB bandwidth by t=0.35 * f-3dB.

If one considers a lower threshold for decay, then the decay time increases significantly.

When we have a BPF Q=fc/Δf(-3dB).  Thus the envelope decay time is equivalent to behaves like the LPF response with a BW = 1/2Δf(-3dB)

Consider applying a DC step voltage to a series R+ L//C parallel resonant circuit. Let L= 1H, C= 250uF fo~10 Hz  Z(10Hz)= 62.8 Ohms  thus for a Q of 10 one chooses Rs=628 Ohms and the envelope decay bandwidth is the single side bandwidth of 5Hz .