LG GSA-4167B - Manual (Page 42)

3. Signal detection of the P/U
1) Focus Error Signal ==> (A+C)-(B+D)
This signal is generated in RF IC (IC101 : R2S35002) and controls the pick-up’s up and down to focus on
Disc.
2) Tracking Error Signal (DPP Method) ==> {(A+D)-(B+C)}- k x {(EF 1 +EF 4 )-(EF 2 +EF 3 )}
This signal is generated in RF IC (IC101 : R2S35002) and controls the pick-up’s left and right shift to find
to track on Disc.
3) RF Signal ==> (A+B+C+D)
This signal is converted to DATA signal in DSP IC (IC301 : R8J32007).
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Pick-Up module
Photo Diode
Tracking
Focusing
Infrared Iaser
k [(F+H) - (E+G)]
(A+D) - (B+C)
(A+D) - (B+C) - k [(F+H) - (E+G)]
Offset
TE
Tp
Sub2
Main
Tp/2
Sub1
Track Center
F,E
D,C
A,B
H,G