(b) The I signal is formed by applying the red signal to the base, and the
blue and green signal to the emitter of the I amplifier (fig 1-20). This circuitry
determines that the output of the red signal will be 180 degrees out of phase with
the other two color signals. Thus the designation is +60 percent red, +28 percent
green, and +32 percent blue. The polarity signs only indicate phase relationships.
The resistor network determines the amplitude of the signals.
(c) The Q signal is formed by applying the green signal to the base and the
red and blue to the emitter of the Q amplifier. Here, the green is 180 degrees out
of phase with the red and blue. The resistor network sets the percentages at -52
percent green, +21 percent red, and 31 percent blue (fig 1-21).
Figure 1-20.
I matrix
Figure 1-21.
Q matrix
c. Band limiting and delay. The outputs of the individual matrix sections feed
the filter section (fig 1-19). The filter section establishes a bandpass for each
of the video signals, 4.1 MHz for Y, 1.5 MHz for I, and 0.5 MHz for Q. The channel
is broad-banded but has vestigal-sideband characteristics because of the upper-
frequency cutoff of the transmitter (fig 1-24).
This channel is single-sideband
for frequencies higher than 0.5 MHz. Transmission of frequencies up to 0.5 MHz is
double-sideband on both the I and Q channels.
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