In my response however, I was distinguishing between
the assessment
of the signal and the properties of the signal, as your response had
alluded to the latter, although we also have the two perspectives to
consider of the agglomeration of possible signals from all disks
versus a given instance. Leaving aside the low probability or
occurrence of someone using the disk for analog PWM or PPM recording,
and other opinions notwithstanding (other thread), I do not consider
a given instance of a (typical) amplitude-normalised (to two states)
read signal from the disk to be analog in the time domain, but from
your other message I think we agree on that.
I think the difference between our approachies is that you're
consisderign a drive and a particular controller combination, I am
considering jus tthe drive.
I agree that the data sent from any normal controller to th edrive when
writing (or formatting) is time-quantized. And that the data read back
from the drive is similar, modulo a bit of jitter and
the magnetic
effects that perecompensation is designed to compensate for.
However, sicen ST506 is a low-level 'raw' interface, you can't assume the
time quatization is the same for all possible controllers. Sicne the
pulse spacing could be any vlaue between given limits (although a
particlar contoller will only use a few differnet psacings), I feel the
drive itslef is analogue in the time domain.
In the analogy with the FSK modem in your other message then: simply
put, whether the demodulated signal is time-quantised depends on the
properties of the modulating signal.
Are you going to argue that a piece of wire is a quantized communications
link just becuase you can send regualrly spaced pulses down it?
-tony