subcarrier
Noun
Meaning
subcarrier (plural subcarriers)
(telecommunications) A separate signal carried on a main radio transmission, often carrying additional information such as voice or data.
Examples
As a result, PAL-M signals are near identical to North American NTSC signals, except for the encoding of the color subcarrier (3.575611 MHz for PAL-M and 3.579545 MHz for NTSC).
As it turns out, the chroma amplitude (when considered together with the Y signal) represents the approximate saturation of a color, and the chroma phase against the subcarrier as reference, approximately represents the hue of the color.
Although, in response to changing U and V values, the chroma sinewave changes phase with respect to the subcarrier, it's not correct to say that the subcarrier is simply "phase modulated".
Colour encoding Both the PAL and the NTSC system use a quadrature amplitude modulated subcarrier carrying the chrominance information added to the luminance video signal to form a composite video baseband signal.
A subcarrier oscillator in the receiver locks onto this signal (see phase-locked loop) to achieve a phase reference, resulting in the oscillator producing the reconstituted subcarrier.
Before transmission, the subcarrier itself, is removed from the active (visible) portion of the video, and moved, in the form of a burst, to the horizontal blanking portion, which is not directly visible on screen.