phase alternating line
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Related to phase alternating line: SECAM
phase alternating line
(television)(PAL) The video signal format used in the UK
PAL uses Amplitude Modulation for the video information, and
Frequency Modulation for the audio information. The phase
of the colour subcarrier is reversed on alternate lines
which (together with the use of a delay line) allows the
receiver to cancel any phase errors introduced in the path
between the studio and the end-user's receiver. Such phase
errors are quite common and would cause the displayed colours
to shift in hue.
The US equivalent, NTSC, does not have this feature and thus requires a user control to correct for transmission phase errors, hence the mis-expansion "Never Twice the Same Colour".
The US equivalent, NTSC, does not have this feature and thus requires a user control to correct for transmission phase errors, hence the mis-expansion "Never Twice the Same Colour".