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DP-7010
CIRCUIT DESCRIPTION
2. CD player unit (X32-137X-XX)
+ D.P.A.C (Digital Pulse Axis Control) circuit
Two different distortions are attendant on the con-
version of the digital signal into an analog signal. One is
a distortion on the level axis (voltage axis), which is
determined mainly by the resolution of the D/A con-
verter, and in case of using a ladder resistor type, by its
error,
The other is a distortion on the time axis, which is not
so prevailing as to appear on the distortion meter but has
e————-€
Original Sound
. — —.__ x Regenerated
ms
* Waveform
Fig. 2-1 Error (distortion) on voltage axis
Next, let us deal with the theory of the D.P.A.C
operation by a basic D.P.A.C circuit of this time.
Also when the latch signal © from the digital filter is
disturbed, an accurate latch signal like © can be ob-
Latch signal (WCKO)
from digital filter.
©
8.4672MHz
great influence on the sound quality. It is the D.P.A.C
that is to operate as a circuit to improve this point.
Figure 2-1 shows the error (distortion) on the voltage
axis of the D/A converter output for the original sound,
and Figure 2-2 shows the error (distortion) on the time
axis of the D/A converter output for the original sound.
As seen from this, even with a variation in time axis,
there appears a regenerated waveform different from
the original sound.
e——————-@
Origina! Sound
Regenerated
Woveform
Fig. 2-2 Error (distortion) on time axis
tained at the rise of the master clock pulse ©). By virtue
of this latch signal, a proper voltage signal is output from
the D/A converter.
Latch signs
[> to D/A converter.
8 AGT2MHz
I
®
H
'
I
Latch signal from digital filter.
1
\
'
{8.4672MHz}
1
1
'
:
\
I
!
Master clock pulse.
(16.9344MH2)
H
+
©
Latch signal to D/A converter.
(8.4672MH2)
Fig. 2-3 D.P.A.C basic circuit
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