Glossary
VTM-2400 Installation and Operation Handbook
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Packet
A packet consists of a header followed by a number of contiguous bytes from an
elementary data stream. It is a layer in the system coding syntax.
Packetized Elementary Stream (PES)
The data structure used to carry elementary
stream data. The packets consist of a header followed by payload data, and a stream is a
series of packets which form an elementary stream and have a single stream identification.
PAL
Phase Alternation Line; the standard color television system in many European and
other countries.
Passive Looping
Video and audio signals routed through components, even if power is
removed. Signals are not amplified or processed, maintaining transparency.
Pedestal Level
An offset used in a video system to separate the active video from the
blanking level by maintaining the black level above the blanking level by a small amount.
Pixel
A Picture cell or Picture element representing one sample of picture information, such
as an individual sample of R, G, B, luminance or chrominance.
Preset
Refers to establishing any condition prior to use on the Program output. This term is
used in reference to wipe patterns and is often interchanged with Preview.
Preview
The video output channel used to view the intended Program results prior to the
execution of the next transition.
PRO Audio
A transmitted audio channel for talent cueing via Interrupt Foldback (IFB) to
ENG vans and remote applications. Some demodulators support PRO audio monitoring.
Program
A transport stream combination of a video stream and one or more audio and data
streams associated with that video stream. In analog terms, “Program” refers to the Base
Band video and audio produced by the final output of a switcher.
Program Association Table (PAT)
A list of all programs that are in the ATSC data stream.
Program Map Table (PMT)
A listing of all elementary streams that comprise a complete
(television) program.
Program Clock Reference (PCR)
This is a time reference signal that is placed in MPEG
streams for the purpose of time coordinating various data streams.
Program and System Information Protocol (PSIP)
Information sent out as part of an
ATSC transport stream which lists all of the video, audio, data and program information
contained in the stream. This is the "TV guide" for a given stream.
Progressive Scanning
Also non-interlaced. A system of video scanning where lines of a
picture are transmitted consecutively, such as with VGA monitor displays.
Push-push Toggle Switch
An electro-mechanical device which, when pushed, alternates
the condition of the switch. Push once, it's off, push again, it's on.
Quadrature Output
An output in a television demodulator used for measuring Incidental
Carrier Phase Modulation (ICPM) in a transmitter.
QPSK
Quadrature Phase Shift Keying, typically used by satellite downlinks.
QAM
Quadrature Amplitude Modulation, the technique used by cable TV systems (64-QAM
and 256-QAM) to remodulate signals for distribution in a cable plant.
