Wegener UNITY4650, Руководство пользователя

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Unity 4650 User’s Manual
800034-01 Rev. A 22 wegener.com
Network Protection
Mode A non-volatile setup parameter whose value is “Shared” or “Protected” (or “not Shared”).
Similarly, each network control stream has a “Share” status field as part of the COMPEL
packet framing. A network control stream is considered “invalid” to the U4650 if the net-
work ID in the stream differs from that of the IRD and if either the network stream or the
U4650 are set to be “Protected”. For test purposes only, there is a generic network ID that
the COMPEL system may transmit which is always considered to be “valid” by all IRDs.
Non-volatile Any memory object (such as a configuration parameter) which holds its value through
power cycles and resets. This is in contrast to volatile memory objects which are lost
through power cycles and (usually) resets.
NTSC National Television System Committee. The composite color video standard used domes-
tically (and in a few countries outside US) based on 525-line 59.97 Hz field rate (with 2:1
interlace).
NVRAM Non-volatile RAM. A random-access memory (RAM) that retains it's value through
power outages (or is non-volatile). Key IRD operating parameters are stored to this type
of memory and may be individually accessed for reading or writing.
PAL Phase-Alternating-Line. A set of composite color video standards used worldwide (out-
side US) which implements a line-by-line reversal of phase of one of the orthogonal color
components. For our use, all PAL signals are assumed to be 625-line 50 Hz field-rate sys-
tems with varying chroma and luma bandwidths and color subcarrier frequencies.
PAT Program Allocation Table. A PSI table within an MPEG transport stream which cross-ref-
erences all available programs to a PID for its PMT. This table is always present in legal
transport streams and must always be in the clear (not scrambled) even when Conditional
Access scrambling is used.
PCR Program Clock Reference. A time-base signal used to synchronize the IRDs internal tim-
ing to the same timing in the MPEG encoder for the received program. Multiple programs
may share a PCR, depending on the multiplexer used to create the final transport stream.
PES Stream Packetized Elementary Stream. The MPEG designation for a compressed component of a
Program (such as audio or video) which includes the timing information necessary for
synchronization (e.g. - synchronizing audio to video).
PID (or Packet ID) The unique transport stream packet identifier assigned to each constituent data stream
within the transport stream. Also, in this document, “PID” is used to designate the stream
itself.
PMT Program Map Table. A PSI table within an MPEG transport stream which cross-refer-
ences a program (or programs) against all the PIDs that bear its component streams (such
as audios, video, DPI, PCR, etc.). IRDs need this table to decode the compressed compo-
nents of that program.
Presets Table A non-volatile table of unit presets. This table is used for either automatic recoveries or as
a shorthand method to quickly reconfigure the unit. The presets table may be pro-
grammed at the factory and edited by the customer, either locally or via network control.
Program A single media stream (combination of audio, video, data, etc.) tied to a common time
base.
Table 3: Glossary of Terms
Term Definition