Service manual

STP 11-25R13-SM-TG
S - 38
S-29. Linearity.
Linearity test signals (Figure S-38) are used to measure nonlinear distortions such as differential
gain, differential phase, and line time linearity.
Figure S-38. Linearity Test Signals
a. Differential gain is basically the change in the chrominance signal amplitude as the amplitude of
the luminance signal changes between black and white. A picture affected by differential gain shows a
change in the saturation of colors.
b. Differential phase is the change in phase of the chrominance signal as the luminance signal
amplitude changes between black and white. A picture affected by differential phase shows a change in
the hues of colors.
c. Luminance nonlinearity is the difference in luminance gain from the black level to the white level
of a video signal. Monochrome signals and the luminance portion of color signals are affected by this
distortion. The linearity test signals consist of either 5 steps, 10 steps, or a ramp.