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PIP CIRCUITS
The new YC Picture In Picture (PIP) system employed on the VB7C (AVM-
2780G) is different from the previous PIP system on the VB7A chassis. The
primary difference between this system and the previous system is that the V-
chip data slicer and the Y/C processing of the sub-picture signal have been
provided in the new PIP Signal Processor.
Since the sub-picture signal is Y/C separated and Y/C processed within the
newly developed PIP Signal Processor, the signal processing is simplified and
the picture quality is improved.
When the PIP circuits are activated by the CPU through the remote control
transmitter, the PIP circuits provide five functions to control the PIP screen.
These are :
1.
PIP On/Off
turns the PIP screen On or Off.
2.
PIP Location
changes the PIP screen position from corner to
corner on the screen.
3.
PIP Swap
switches pictures between the TV’s main screen
and PIP screen.
4.
PIP Freeze
to obtain a still picture on the PIP screen.
5.
PIP Select
to select Video 1 or Video 2 screen.
The PIP signal processing is accomplished by the TV/AV switching circuit, the
PIP Signal Processor and other video circuits. The fundamental operations
are described below.
PIP Signal Processor
The PIP Signal Processor IC8001 is composed of the sub-picture Y/C
processing circuits and the Y/C Input/Output Switch. The PIP Signal
Processor contains the sub-picture signal processing circuit. The built-in field
memory (96K-bit RAM) is necessary to provide for the data storage of a sub-
picture into the main-picture of a television.
The sub-picture processing circuit includes the A/D Converter, Y/C Separator,
V-Chip Data Slicer, Timing Control, Vertical Filter, Multiplexer, Field Memory,
Demultiplexer, Encoder, D/A Converters, and Y/C Input/Output Switch. All
necessary controls are provided by registers in the PIP Signal Processor.
These registers are set by external control through the BUS Interface.
One of the TV, AV1 and AV2 composite video signal is selected in the TV/AV
Switching circuits which is controlled by the BUS interface. The selected
video signal is applied to the sub-picture processing circuitry and input to the
Y/C mode switch. The Y/C mode switch selects and inserts the sub-picture
Y/C signal into the main-picture Y/C signal when the PIP mode is selected.
In operation, IC8001 overlays a single sub-picture on the main video in 1/9th
size. In 1/9th the sub-picture is 228 samples (171Y, 28.5 B–Y, 28.5 R–Y) by
69 lines.
The selected TV or AV video is output from the Y/C Input/Output switch (pins
45 and 47 of IC8001) mixed with the PIP overlay when the PIP On mode is
selected. The Y and C signals output from pins 45 and 47 of IC8001 are input
to pins 40 and 38 of the Signal Processor IC101 respectively.
Note:
• Using the S-Video Input jack overrides the Composite Video Input
jack when the AV1 is selected.
