Modem
“Modem” is a contraction of Modulator-
Demodulator. A Modem converts computer
digital signals to analogue for data
transmission, or demodulates upon receipt,
for use within a computer.
Modulate
To regulate, or adjust, and specifically in the
case of communications, to regulate some
parameter of a high-frequency carrier wave by
means of a low-frequency information signal.
(Roddy/Coolen)
NCTA
National Cable Television Association: the
trade association for the U. S. cable television
industry. Formerly called National Community
Television Association.
Node
A point of connection and distribution
downstream from the hub. A node supports
an average of about 500 subscribers
Noise Offset
For a true indication of Mean Noise value in
the system, measure C/N ratio at about
2.4/2.5 MHz above the lower band edge,
between video and chrominance modulation.
Overlapping
Channel
Many countries have similar but slightly
different frequency allocation for channels.
To accommodate all possible variations,
Stealth base channel plans have some
overlapping frequencies. Carrier frequencies
are different, but there is some bandwidth
overlap. if you use one of these channel
plans, delete unused channels that overlap
active channels.
NTSC
National Television System Committee: the
organization that established a color television
standard with the same name used by the US
and several other countries. The standard
uses a 525-line screen at a rate of sixty
fields/thirty frames per second, with a
broadcast bandwidth of 4 MHz. Horizontal
resolution is approximately 768 pixels.
PAL
Phase Alternate Line: a European color
television system, not compatible with the
NTSC system used in the United States