What is meant by "information encoded in time domain"? Author on pg 292 claims the windowed-sinc &quot;is not a filter for signals with information encoded in time domain&quot;, because its &quot;step response has overshoot and ringing&quot;. That phrase, along &quot;encoded in frequency domain&quot;, are used in text, but I'm unsure they're ever explicitly defined. My guess:

Frequency-domain encoded: periodic processes in a system - something that recurs, persists the duration of the signal, and is sensibly described by Fourier coefficients
Time-domain encoded: the opposite - time-local events in a system, such as a sharp rise, temporary change in DC offset, momentary noise injection.

A single square pulse would qualify for latter, as the physical system that generated it almost certainly didn't synch hundreds of sinusoidal sources just right. A noiseless EEG would qualfiy for former, as neuronal excitations recorded as polarity alignments have periodic traits.
Is this accurate? If so, how is a filter's step response relevant in describing time-local events - and are there other &quot;responses&quot; characterizing time-encoded information?

Note: I'm aware of the step response's role in control systems, circuit design; I ask specifically about non-periodic &quot;events&quot; in a signal (if that's what time-encoded means).
The simplest (imho) explanation is this.
Consider a time-domain signal which has narrow pulses or sudden jumps in value or on/off switches at certain (unknown!) time instants. Such a signal is said to carry its information in those specific time instants at which such sudden changes occur.
A PWM (pulse width modulation) signal is an excellent example for such class of signals.
If you consider the frequency domain reflection of those sudden changes in the signal amplitudes, you will see that they have wide band spectrums. They are local in time, therefore spread in frequency.
When you filter such a signal with a typical LPF (low pas filter) or alike, which discards parts of the spectrum away and passes only a subset of it, you may effectively be throwing away part of the information that's carried by the signal too.
For example, the specific instants at which the PWM wave switches on/off becomes blurry, and hence the resolution of the information is reduced.
The author seems to mention this issue with filtering of time-domain encoded information...