saa7803 NXP Semiconductors, saa7803 Datasheet - Page 49

• Manufacturer Part Number: saa7803
• Description: Saa7803 One Chip Cd Audio Device
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13695
Objective data sheet
In the case of a single foucault focusing method, the signal conditioning can be switched
under software control such that the signal processing is as follows:
The error signal, FE
filter section.
An internal flag is generated by means of the central aperture signal and an adjustable
reference level. This signal is used to provide extra protection for the Track-Loss (TL)
generation, the focus start-up procedure and the dropout detection.
The radial or tracking error signal is generated by the satellite detector signals R1 and R2.
The Radial Error (RE) signal can be formulated as follows:
where the index ‘s’ indicates the automatic scaling operation which is performed on the
radial error signal. This scaling is necessary to avoid non-optimum dynamic range usage
in the digital representation and reduces the radial bandwidth spread. Furthermore, the
radial error signal will be made free from offset during start-up of the disc.
The four signals from the central aperture detectors, together with the satellite detector
signals generate a Track Position Indicator (TPI) which can be formulated as follows:
where the weighting factor sum_gain is generated internally by the SAA7803 during
initialization.
FE
RE
TPI
Fig 29. Detector arrangement
n
s
=
=
=
single Foucault
SATELLITE
SATELLITE
DIODE R1
DIODE R2
sign D1
D3
2
R1 R2
---------------------
D1
D1 D2
–
D1
D2
–
+
D2
+
D2
re_gain
n
, is further processed by a Proportional Integral and Differential (PID)
+
Rev. 01 — 19 April 2005
D3
+
+
D4
R1
+
–
R2
R1
astigmatic focus
+
re_offset
SATELLITE
SATELLITE
DIODE R1
DIODE R2
D2
D4
R2
D1
D3
sum_gain
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
One chip CD audio device
SAA7803
double Foucault
SATELLITE
SATELLITE
DIODE R1
DIODE R2
D1
D2
D3
D4
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