SAA7374GP PHILIPS [NXP Semiconductors], SAA7374GP Datasheet - Page 15

• Manufacturer Part Number: SAA7374GP
• Description: Low voltage digital servo processor and Compact Disc decoder CD7LV
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
7.7.3
A 1-sample linear interpolator becomes active if a single
sample is flagged as erroneous but cannot be corrected.
The erroneous sample is replaced by a level midway
between the preceding and following samples. Left and
right channels have independent interpolators. If more
than one consecutive non-correctable sample is found, the
last good sample is held. A 1-sample linear interpolation is
then performed before the next good sample (see Fig.10).
In CD-ROM modes (i.e. the DAC interface is selected to be
in a CD-ROM format) concealment is not executed.
7.7.4
A digital level controller is present on the SAA7374 which
performs the functions of soft mute, full scale, attenuation
and fade; these are selected via register 0.
1998 Feb 26
Mute: signal reduced to 0 in a maximum of 128 steps;
(3/n) s.
Attenuate: signal scaled by 12 dB.
Full scale: ramp signal back to 0 dB level. From mute
takes (3/n) s.
Low voltage digital servo processor and
Compact Disc decoder (CD7LV)
C
M
ONCEALMENT
UTE
,
FULL
-
SPEED
,
ATTENUATION AND FADE
OK
Interpolation
Error
Fig.10 Concealment mechanism.
OK
Error
Hold
15
7.7.5
The peak detector measures the highest audio level
(absolute value) on positive peaks for left and right
channels. The 8 most significant bits are output in the
Q-channel data in place of the CRC bits. Bits 81 to 88
contain the left peak value (bit 88 = MSB) and
bits 89 to 96 contain the right peak value (bit 96 = MSB).
The values are reset after reading Q-channel data via
SDA.
Error
Fade: activates a 128 stage counter which allows the
signal to be scaled up/down by 0.07 dB steps
128 = full scale.
120 = 0.5 dB (i.e. full scale if oversampling filter
used).
32 = 12 dB.
0 = mute.
Error
P
Interpolation
EAK DETECTOR
OK
OK
MGA372
Product specification
SAA7374