1U:
Abbreviation for one unit or rack space. U = 1.75
inches.
4B5B
Encoding:
A
signal modulation scheme in which groups of four bits are
encoded and transmitted in five bits in order to guarantee
that no more than three consecutive zeroes ever occur; used in
FDDI.
4:1:1:
The set of sampling frequencies used to digitize the luminance
and color difference components (Y, R-Y, B-Y) of a video
signal. The four represents 13.5MHz, the sampling frequency
of Y, and the ones each 3.75MHz for R-Y and B-Y.
4:2:0:
A sampling system used to digitize the luminance and color
difference components (Y, R-Y, B-Y) of a video signal. The
four represents the 13.5MHz sampling frequency of Y, while
the R-Y and B-Y are sampled at 6.75MHz effectively
between every other line only (one line is sampled at 4:0:0,
luminance only, and the next at 4:2:2).
4:2:2:
A commonly used term for a component digital video format. It
is generally used as shorthand for ITU-R
601. 4:2:2 is the standard for digital studio equipment.
4fsc:
Abbreviation for four times the frequency of SC (subcarrier).
The sampling
rate
of a D2 digital video signal with respect to the subcarrier
frequency of a video signal. The 4fsc
frequency is 14.3MHz in NTSC
and 17.7MHz in PAL.
8B10B
Encoding:
A signal modulation scheme in which eight bits are encoded in
a 10-bit word to ensure that too many consecutive zeroes do
not occur; used in ESCON
and fibre
channel.
