> Finite Impulse Response (FIR) filters don't ring in the same sense
> as
> a traditional analog filter or its DSP cousin the Infinite Impulse
> Response (IIR).
>
> The worst thing you can get from a narrowband FIR is a short chirp
> in
> response to an impulse input. This will persist for a couple of
> cycles whereas an analog filter with equivalent bandwidth (Q) will
> ring all day.
Rise and fall times of a CW signal require bandwidth.
Make the bandwidth narrow, and the rise and fall times always
increase.
It is this "softening" that most people call ringing, because it
"blurs" high speed CW or even noise pulses into an almost steady
sounding tone.
73, Tom W8JI
w8ji@contesting.com
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