DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

Most lines have a single normalwidth
sync pulse.
About a dozen lines of each
frame contain equalization pulses.
About half a dozen lines of each
frame contain broad pulses.
The equalization and broad pulses
display on a waveform monitor as
faint “phantom” traces.
Figure 34.4 “Phantom” sync traces
The term composite is overused in
video. In the context of sync, it
refers to combined horizontal and
vertical elements, and is unrelated
to the combining of luma
and modulated chroma!
SMPTE 318M, Reference Signals for
the Synchronization of 59.94- or 50-
Hz Related Video and Audio Systems
in Analog and Digital Areas.
Sync distribution
Synchronization was once achieved in studio and
network facilities by distributing multiple pulse signals,
usually having amplitudes of 4 VPP or 2 VPP . Figure 6.7,
on page 58, sketched the horizontal drive (HD) and
vertical drive (VD) pulses that were once common.
Nowadays, composite sync has amplitude of either
2855⁄ 7 mV (in 480i systems with 10:4 picture:sync
ratio) or 300 mV (in 480i systems with EBU N10 (curiously
called “SMPTE”) levels, 576i, and HDTV). Sync
can be regarded as a legitimate video signal, with zero
setup, no burst, and picture information that is entirely
black.
When R’G’B’ is accompanied by separate HD and VD
signals, this is denoted RGBHV. When separate “composite”
sync accompanies R’G’B’, this is denoted RGBS.
To distribute timing information among component
analog video equipment, it is conventional to distribute
a blackburst or colorblack reference signal comprising
sync, blanking, and burst (and optionally, setup). Blackburst
represents an entirely black picture, with zero
luma and zero chroma everywhere. SMPTE 318M
defines a colorframe pulse signal that may be included
on lines 15 and 278 in 480i systems.
Although a component video signal per se has no burst,
it is common to include burst on the reference video
signals of SDTV component video systems.
404 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES