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Circuit Descriptions, Abbreviation List, and IC Data Sheets

Signal IF-TER from the tuner is fed to pin 1 and 2, IF circuits of
TDA8887H IC7301 via SAW filter 1352. The AGC voltage for
the tuner can be adjusted in the SAM tuner menu (2nd AGC).

Source selection
After IF demodulation, the CVBS-PIP-OUT is fed back to
TDA888x pin 24 with or without video switching circuit
comprises of 7402 (HEF4053). Due to this construction, two
independent RF signal pictures can be selectively displayed on
the CRTs screen. See table.

Table 9-1 Switching logic for Main and DW Picture

The source signals are fed directly to video processor IC7301.
The IC performs the source selection internally.
The video processor IC7301 decodes the CVBS at pin 24 or pin
29 into YC signals and further process it into YUV signal.
Output is at pins 40, 45, and 46.
The PIP-AUDIO signal is fed to pin 47 of the audio demodulator
MSP34xx on the SSB.

Note: When S-VHS is inserted from the rear, the AV2 source
will be disabled. Likewise, when S-VHS is inserted from the
side-AV.

9.3.4

DW/PIP processing

The SAB908x (IC7801) is a multi-standard PIP controller,
which can be used in double window or PIP applications. The
YUV signals from the video processor IC7301 are fed to pin 79,
81, and 83. The PIP controller will insert the YUV signals from
IC7301 with reduced size into the main picture. The main
picture YUV signals (50 Hz) are fed to pins 100, 2, and 98,
respectively. These signals are used during the DW mode.

Inside IC7801, the conversion to the digital environment is
done with ADCs. Processing and storage (1 MB DRAM) of the
video data is done entirely in the digital domain. The
conversion back to the analogue domain is done by DACs.
Internal clocks are generated by PLLs, which lock on to the
applied horizontal and vertical syncs from the main and sub
pictures. The main picture syncs are applied to pin 70 (V) and
pin 94 (H) and the sub picture syncs are applied to pin 72 (V)
and pin 87 (H).
For DW mode, the main picture is compressed horizontally by
a factor of two and fed directly to the output. After compression,
a horizontal expansion of two is possible for the main picture.
The sub picture is also compressed horizontally by a factor two,
but is stored in memory before it is fed to the outputs.

Post-processed YUV signals are fed to the "fast switching"
IC7803 (TDA8601 pins 6, 7, and 8). In normal operation
(without DW), the main picture YUV signals (at pins 2, 3 and 4)
are bypassed by IC7803, and returned back to the main video
processor. When DW mode is active, the compressed YUV
signals (main and sub pictures) are used and fed to the main
video processor. During the PIP mode, only sub-picture YUV
signals are used. The insertion control is made possible by a
fast blanking signal from pin 68 of IC7801.

9.3.5

Power supplies

The power supplies used by the DW panel are from the main
board 5 V, 8 V, and 33 V (for tuner only). IC7802 LM317T
regulates the 5V to +3.3V, +3V, and +3VD. These voltages are
mainly used by the DW processor circuitry. The 8V is mainly
supplied to the IF + video processing circuitry (IC7301
TDA888x), and to fast switching IC7803.

9.4

Abbreviation list

2DNR

Spatial (2D) Noise Reduction

3DNR

Temporal (3D) Noise Reduction

AARA

Automatic Aspect Ratio Adaptation:
algorithm that adapts aspect ratio to
remove horizontal black bars; keeping
up the original aspect ratio

ACI

Automatic Channel Installation:
algorithm that installs TV sets directly
from cable network by means of a
predefined TXT page

ADC

Analogue to Digital Converter