Figure 8-12.--The color camera unit.
channel frequency. Modulating the subcarrier makes it
each of the primary colors). Filters and mirrors are
possible to broadcast the color information of the I and
used to direct the right color of light to its respective
Q signals simultaneously without loss of identity. Each
pickup tube. The output of the camera unit provides a
can be recovered as a separate signal with the proper
red, green, and blue video signal to the matrix system
timing of the transmitter and the receiver. The combined
(a circuit that proportions the primary signals to
outputs are designated as the chrominance C signal and
produce the correct brightness and chrominance
are routed to the adder (fig, 8-12).
colors). The three primary colors are identified as R
for red, G for green, and B for blue.
The chrominance C signal (the color information)
and the Y signal (the luminance information) are both
The matrix section is essentially a resistive
coupled to the adder section, or colorplexer. The
voltage divider circuit that proportions the primary
colorplexer combines the Y and C signals, forming the
color signals to produce the brightness and
total video S signal which is sent to the transmitter.
chrominance signals. With the red, green, and blue
color video voltages as inputs, the three video signal
output combinations formed are the following:
Luminance signal, designated the Y signal,
The received signals of video and sound enter the
which contains the brightness variations of the
receiver/monitor just as they do in black-and-white
reception. The same tuner and IF amplifiers are used
(fig. 8-13). In the video amplifier the signals separate.
A color video signal, designated the Q signal,
which corresponds to either green or purple
A color video signal, designated the I signal,
which corresponds to either orange or cyan
The I and Q signals together contain the color
information for the chrominance (hue and saturation)
The I and Q signals are transmitted to the receiver
as the sidebands of a 3.58-MHz subcarrier wave (fig.
8-12). A subcarrier wave is a relatively low-frequency
carrier wave that modulates the main carrier wave. The
Figure 8-13.--Color TV receiver, block diagram.
subcarrier frequency remains the same regardless of the