Philips DVDR985 Technical Training Manual page 52

and tilt sensor signal. The HF/RF (EMF) signal
varies greatly between disc formats. The Focus
Error and Radial Error signals come from the
mechanism on the Q1-6 signal paths. The Tilt
Error has a Photo Tilt Sensor. The dynamic
range of these signals is very large. They are
converted to Lower frequency RF data paths that
the MACE3 can accommodate. This is required
for playability of the many different kinds of
discs.The error signals are all balanced to
reduce noise interference. Thus, they are named
XX positive, and XX negative. The Output sig-
nals include: the Focus Error, the Radial Error,
the Tilt error, laser PoWer, and tracking loss sig-
nals.
The Record RF EFM data and EFM Clock
comes from IC 7402, Encoder circuit, and is sup-
plied to the SPIDRE on Pins 48-51 of 7101. The
SPIDRE processes the RF signals for gain con-
trol of the Error control signals going to the
MACE3 during record. All of these signals are
balanced. Thus there is a negative and a posi-
tive signal for all of them.
The LASP, Laser Power feedback signal is
processed by the SPIDRE. During playback, the
EFM coming from the disc is used by the ALFA
circuit to generate the AMEAS, ALFA
Measurement, signal that goes back to the
LADIC for precise control of the LASER power.
During record the EFM signal coming from the
Encoder is used by the ALFA circuit to create the
AMEAS signal.
The pregrove tracking error signal comes from a
Preprocessor in the OPU. The PPN signal is
amplified and sent to the Wobble Processor in
the Decoder circuit.
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