GRASS VALLEY 1200, Installation And Service

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3-5
System Overview
Video Signals
Standard System
The Model 1200 uses a 10-bit parallel digital component signal internally
with serial digital video converters at input and output. The signal is split
into luminance and chrominance channels. If the input signal is 8 bits, the
extra two bits are internally forced low.
The Standard Model 1200 system consists of a control panel, a signal
processor frame and an interconnect cable. With the standard system the
video takes the following paths (see Figure 3-1 on page 3Ð2):
Input ModulesÑ
Each input goes through a Serial or Parallel Input Module
where the signal is converted to the TTL level parallel video that is required
by the Model 1200. The clock is also stripped off for timing the video.
Crosspoint ModuleÑ After going through the Input Module the video is sent
to the Crosspoint Module. The Crosspoint Module has several functions:
■
Timing all the inputs
■
Splitting the inputs into luminance and chrominance (video) or key and
depth (keys)
■
Connecting inputs to the internal buses
■
Generating mattes
■
Interfacing to the Chroma Keyer Submodule option
First the signal enters the auto timing circuit which times all the inputs and
splits the signals into luminance and chrominance. The video then enters
the main crosspoint matrix which assigns each input to a particular input
pushbutton on the control panel. The matrix also connects the inputs to
the appropriate internal bus. Each crosspoint also has a matte generator
built in.
Keyer ModuleÑ If the selected video is a key or aux bus, the video is
transferred to the Keyer Module. The Keyer Module does the following:
■
Interfaces to the Key Processor Submodule
■
Does the Effects Send
■
Creates control signals for the wipes (wipe solid generator)
The Effects Send circuit can send the selected video and key from the key
process to the aux bus outputs to a DPM. The modified signals are then
reentered into primary inputs and routed to the mixer circuit. This allows
a DPM to be inserted into the signal path between the Key Proc and the
Mixer.