Harmonic Ellipse 3000, Руководство пользователя, Страница: 389 / 403

Glossary
Numerics
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© 2013 Harmonic Inc. 389 Ellipse 3000 r.3.0, Rev. B
output transport
An NMX term, an output transport contains all of the output devices for a transport in a
single, easy-to access place. Output devices can include devices such as an ATM interface, ASI
interface, and so on. The output transport enables you to access the menus needed to create
the circuits and programs that the
broadcast encoding system
manages. An output transport
only contains output devices, and output devices only have input ports. These input ports
connect to the output of either an encoder (in a small system) or a remultiplexer (in a large
system).
P
packet
A block of data used for transmission.
PAL
Phase Alternate Line. The analog composite television standard used in much of Europe and
Asia. PAL transmits 625 lines per frame at 25 frames per second using interlaced scanning.
PAT
Program Association Table. This table indicates the location (the
PID
values of the transport
stream packets) of the corresponding Program Map Table (
PMT
), as well as the location of
the Network Information Table (
NIT
).
path
For a network system, the route down a menu hierarchy to a specific submenu, menu option,
or parameter. The visual display shows each submenu as two or more letters plus a colon to
represent a path.
PCR
Program Clock Reference. This is a field defined by MPEG-2 Systems, which carries a sample
of the encoder’s 27-MHz reference clock. The PCR values are periodically inserted into the
Transport Stream, and used by the decoder to reconstruct the clock and maintain
synchronization with the encoder.
PDU
Protocol Data Unit. A data unit that is specified in a layered protocol that consists of protocol
control information and layer user data.
pel
Picture Element — also known as a pixel.
PER
Packet Error Rate.
PiP
Picture in Picture.