Harmonic ProView 7000, Руководство пользователя

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Glossary
Numerics
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© 2012 Harmonic Inc. 212 ProView 7000 v.2.6, Rev. E
NTSC
National Television Systems Committee. This committee created the analog composite television
standard once used in the United States, Japan, and several other countries. The standard transmits
525 lines at 29.97 (30/1.001) fields per second (interlaced) in the United States, Canada, and Mexico,
and 525 lines at 30 fields per second (interlaced) in Japan. See also
ATSC
.
NVRAM
Non-Volatile Random Access Memory. NVRAM is usually implemented using static RAM with a battery
backup system, which enables it to retain data after the power is turned off.
O
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
).
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.
PER
Packet Error Rate.
PES
Packetized Elementary Stream. The MPEG-2 data structure used to carry elementary streams over
physical media. The PES packet payload consists of data from a single elementary stream.
physical address
See
MAC address
.
PID
Packet Identifier. Integer values used in the MPEG-2 Systems standard to identify each elementary
stream within a program within a transport stream.
PMT
Program Map Table. An MPEG-2 Program Specific Information (
PSI
) table that maps the PID values to
each elementary stream (and stream type) that comprises the
program
.