Differential gain

Differential gain is a kind of linearity distortion that affects the amplification and transmission of analog signals.

It can visibly affect color saturation in analog TV broadcasting.

The composite color video signal (CCVS) consists of three terms: The first two terms are usually called composite video signal (CVS) The modulation technique of the color subcarrier is quadrature amplitude modulation (QUAM) both in PAL and NTSC systems.

Let CCVS be represented by The output of an ideal amplifier with the amplification factor of A is; However, in practice this goal is almost never attained.

in NTSC) The sawtooth represents the CVS with all possible levels between 0.3 V to 1 V. The waveforms are shown in the accompanying image frame.

But PAL (phase alternating at line rate) is more sensitive to this kind of distortion.

PAL averages phase differences of color signal in two consecutive lines.