Installation guide
~PRECOMPENSAnON
If
you
were to
look
at
the
drive's
data
Signals
they
would
appear
as
electronic
pulses.
The frequencies
used
to
generate
.these
pulses
are
stepped
up
and
down
at
very
specif1c intervals.
This
is
necessary
for
the
controller
to
be
able
to
track
the
data
as
it
is
being
read. .
As
the
drive
records
toward
the
inner
portions
of
the
disk
these
precisely
timed
.-
-
pulses-begin
to
shift~·
This·
degrades
its
reliability:---Fortunateiy;-the-shiftoccurs-irr
a predictable
manner
which
can
be
corrected
by
the
controller. If
the
shift
will
cause
a
shorter
pulse
the
controller
will
write
the
pulse
longer.
This
causes
the
pulse
to shift
closer
to
the
correct
time interval.
The
predictable
shifting
of
the
data
signal
is
precompensated
to
cancel
the
effect
of
writing
at
the
inner
portion
of
the
disk.
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