Wegener DTV742, Руководство пользователя

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DTV 742 User’s Manual
800057-01 Rev. B 12 wegener.com
PCR Program Clock Reference - a time-base signal used to synchronize the DTV742's tim-
ing to the MPEG encoder for that program. Multiple programs may share a PCR,
depending on the multiplexer used to create the final transport stream.
PID Packet Identifier - the unique transport stream packet identifier assigned to each constit-
uent data stream within the transport stream.
Also, in this document, “PID” is used to
designate the stream itself.
PMT Program Map Table - table for a given program identifying all the PIDs for its PCR,
video, audio, and user data streams
Program In the MPEG hierarchy, a grouping of related audio, video, or generic data PIDs sharing
a common PCR time base and (usually) sharing a common schedule (see PMT)
PSI Tables Program-Specific Information Tables - a group of information-bearing tables, each
borne by well-known PIDs, regularly transmitted in the transport stream (See also
“PAT” and “PMT”. Also, ISO 13818-1 gives a thorough description of these and other
tables.)
PSIP Program and System Information Protocol - a method for transporting digital television
system information and electronic program guide data
RAM Random access memory - a general term for all memory volatile memory types out of
which application software executes and into which its variables, state information, and
messages are stored. RAM is also used to designate the volatile storage used by the
transport demux and decompression devices.
RF Radio frequency
SNMP Simple Network Management Protocol - A network protocol used to manage TCP/IP
networks. This protocol provides functions that enable access to data objects whose
definitions are located in the MIB.
TMRA Maximum Recommended Ambient Temperature - the highest operating temperature for
which the unit is rated
Transport Stream
(or MPEG Trans-
port Stream) A multiplex of several data streams, each of which is borne in transport packets, 188-
byte blocks containing a sync word, header information (including a PID), and payload
data. This multiplex includes PSI data tables, programs, padding in the form of null
packets, and floating PIDs such as those used by COMPEL network control.
Table 2: Glossary of Terms
Term Definition