Glossary
© 2012 Harmonic Inc.
213
ProView 7000 v.2.6, Rev. E
port
A port is an input to or an output from a
, or a module.
program
In MPEG-2 Systems, a program is a collection of video, audio, and data elementary streams carried in a
TS that share a common clock reference.
PSI
Program Specific Information. A set of MPEG-2 inband control tables. The tables contain tuning
information, information about the relationships between the various elementary streams, and
conditional access information.
See also
.
PSIP
Program and System Information Protocol
PTS
Presentation Time Stamp. An MPEG-2 defined field that can be present in the
packet header to
indicate the time the access unit is to be presented (displayed) to the viewer.
Q
QAM
Quadrature Amplitude Modulation. Transmits 4 bits (16 QAM) to 8 bits (64 QAM) at the same time by
varying the phase and amplitude of a signal.
QPSK
Quaternary Phase Shift Keying. QPSK transmits 2 bits at the same time by varying the phase of the
signal.
R
Redundancy
A back-up system of Harmonic components that ensures uninterruptible service in the event of
a
failure.
Reed-Solomon decoder
A device that performs error correction on the incoming data stream.
reference clock
The 27-MHz abstract clock from which various physical clocks are instantiated. The encoder maintains
a 27 MHz encoder clock, and via correct placement of PCR values into the Transport Stream, the
decoder is able to reconstruct the reference clock in the form of a decoder clock.
reference level
Reference level is the nominal level to which all parts of an audio signal chain are aligned. This is
co4 dBu or 0 dBu for analog audio systems. It is measured in an out of service measurement
where a sine-wave tone of the nominal level is introduced at the entrance of the system and then the
