Glossary
HE4000 Encoding System
NTSC
1.
National Television Standards Committee of the Electronic Industries
Association (EIA). A committee which determines the video standards
for broadcast in the U.S.
2.
The U.S. standard for video broadcast which uses a 3.57945 MHz
subcarrier whose phase varies with the instantaneous hue of the
televised color, and whose amplitude varies with the instantaneous
saturation of the color. A single frame (picture) in the standard consists
of 525 horizontal scanning lines. Frames are scanned at the rate of
29.97 frames per second.
3.
Used to describe the standard method of television transmission in the
U. S., Canada, Japan, Central America, and parts of South America.
NVRAM
Non-Volatile Random Access Memory
N/C
No Connection or Not Connected
O
OC-3
Optical Carrier Level 3 (155.52 Mbps); refer to STM-1.
Ohm
A unit of measure for resistance symbolized by the Greek letter omega W.
Defined as the electrical resistance between two points of a conductor when a
constant difference of potential of 1 volt, applied between these points produces
in this conductor a current of 1 ampere, the conductor not being the source of
any electromotive force.
OQPSK
Offset Quadrature Phase Shift Keying
Overhead
A number of data bits used for error-checking, control, timing, and other
communications functions that are inserted in the data stream as an additional
to the individual data rates of the transport stream components. Overhead must
be included when calculating the aggregate transport stream output data rate.
P
PAL
Phase Alteration Line.
1.
A broadcast television standard that uses a subcarrier which is
alternated 90 degrees in phase from one line to the next to minimize hue
errors in color transmission.
2.
The color television transmission standard used in Europe and many
other parts of the world.
PAL-I
A European color television transmission standard that uses a 4.43361875 MHz
subcarrier. A single frame in this standard consists of 625 scanning line, and
frames are scanned at a rate of 25 frames per second.
PC
Personal Computer
PD Buffer
Plesiochronous/Doppler Buffer
PGCA
A proprietary conditional access method used by ComtechTV equipment that
provides basic signal protection and the ability to authorize individual IRDs.
PID
Packet Identifier. Within a data packet, the bits used for its identification.
GL-8
01-0951-404 Rev B
