Instruction manual

Page 66
UTY4422-001 Page 66 of 74
MPEG, MPEG Transport Stream
- Moving Picture Experts Group. This catchall
abbreviation is used to describe the digital compression (redundancy reduction) of linearly-
digitized audio and video signals as well as the mode of multiplexing and transporting that
compressed data. The Transport stream is a packetized system consisting of a sequence of 188-
byte packets, each with a sync-byte and a specific payload identified by a payload ID (or PID).
The stream contains packets not only for the compressed audio and video, but also auxiliary
data, program information and allocation data, and conditional access information.
PID
- Payload Identifier (or ID). See "MPEG."
PMT
– Program Map Table. In an MPEG Data Stream, this Data Packet contains the PID’s of
subsequent Packets that contain each Program’s compressed Video, Audio, or Data.
QPSK
- Quadrature Phase Shift Keying. This is a popular mode of transmitting digital
information by varying the phase of a radio-frequency carrier.
SCPC
- Single-Channel-Per-Carrier. Only one service or program is present on a particular
radio-frequency carrier.
SETTINGS TABLE
- An internal table of alternate carrier/program settings stored in the IRDs
non-volatile memory (remembered through power cycles). This table may be used in the
following ways: (1) If an IRD is unable to acquire the commanded carrier, then it will, after an
appropriate time-delay, search for and lock onto any carriers in the table it may be able to find.
(2) If local control is enabled, a user, may, through the front-panel or terminal command, tune
the IRD to a new setting found in the table using the shorthand of the Settings Table entry
number.
TMRA –
Temperature Mounting Rack Ambient – The ambient temperature of the mounting
rack where the equipment is located. This temperature is more relevant to the operating
condition of the equipment than the ambient temperature of the room where the equipment rack
is located.