Glossary
Program
PC - A sequence of instructions for a computer.
TV - A concept having a precise definition within ISO 13818-1
(MPEG-2). For a transport stream, the timebase is defined by the
PCR. The use of the PCR for timing information creates a virtual
channel within the stream.
Programme
A linking of one or more events under the control of a broadcaster.
For example, football match, news, film show. In the MPEG-2
concept, the collection of elementary streams comprising the
programme, have a common start and end time. A series of
programmes are referred to as events.
P
R
P
B
Analogue Color difference signals. Refer to C
R
C
B
for an explanation.
PS
Program Stream: A combination of one or more PESs with a
common timebase.
PSI
Program Specific Information: Consists of normative data, which is
necessary for the de-multiplexing of transport streams and the
successful regeneration of programs (see also: SI).
PSIP
Program System Information Protocol: The ATSC equivalent of SI
for DVB.
PSK
Phase Shift Keying: A method of modulating digital signals
particularly suited to satellite transmission.
PSR Professional Satellite Receiver: See also: IRD.
PSU
Power Supply Unit.
QAM
Quadrature Amplitude Modulation: A method of modulating digital
signals, which uses combined techniques of phase modulation and
amplitude modulation. It is particularly suited to cable networks.
QoS
Quality of Service. A common term for a set of parameters
describing the quality you get from an IP network: Throughput,
availability, delay, jitter and packet loss.
QPSK
Quadrature Phase Shift Keying: A form of phase shift keying
modulation using four states.
QSIF
Quarter Screen Image Format.
Quantise
A process of converting analogue waveforms to digital information.
8-bit quantization as set out in ITU-R Rec. 601. Uses 256 levels in
the range 0 – 255 to determine the analogue waveform value at any
given point. The value is then converted to a digital number for
processing in the digital domain.
RAM
Random Access Memory: A volatile storage device for digital data.
Data may be written to, or read from, the device as often as
required. When power is removed, the data it contains is lost.
RAS
Remote Authorization System: An Ericsson AB proprietary public-
key encryption system used to prevent unauthorized viewing of a TV
programme or programmes.
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