TANDBERG E5780, Справочное руководство

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Glossary
Reference Guide: evolution 5000 E5780 and E5782 Encoder Page A-9
ST.RE.E10135.4
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.
PTS Presentation Time Stamp (ATSC).
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.
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 quantisation 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: A TANDBERG TV proprietary public-key encryption system used to prevent
unauthorized viewing of a TV programme or programmes.
RF Radio Frequency.
RFC The Requests for Comments (RFC) document series is a set of technical and organizational notes about the
Internet (originally the ARPANET), beginning in 1969. Memos in the RFC series discuss many aspects of
computer networking, including streaming protocols, procedures, programs, and concepts but are taken as the
Standard.
ROM Read Only Memory: A non-volatile storage device for digital data. Data has been stored permanently in this
device. No further information may be stored (written) there and the data it holds cannot be erased. Data may be
read as often as required.
RS Reed-Solomon coding: An error detection and correction, coding system. 16 bytes of Reed-Solomon Forward
Error Correction code are appended to the packet before transmission, bringing the packet length to 204 bytes.
The 16 bytes are used at the receiving end to correct any errors. Up to eight corrupted bytes can be corrected.
RLC Run Length Coding: Minimisation of the length of a bitstream by replacing repeated characters with an instruction
of the form ‘repeat character x y times’.
SCPC Single Channel Per Carrier.
Spectral Scrambling A process (in digital transmission) used to combine a digital signal with a pseudo-random sequence, producing a
randomised digital signal that conveys the original information in a form optimised for a broadcast channel.
Scrambling
Alteration of the characteristics of a television signal in order to prevent unauthorised reception of the information
in clear form.
SBR Spectral Band Replication is a tool used in MPEG-4 AAC to allow sub-64kbit/s stereo encoding for broadcast
transmissions.
SDI Serial Digital Interface.
SDT Service Description Table: Provides information in the SI stream about the services in the system; for example,
the name of the service, the service provider, etc.
SELV Safety Extra Low Voltage (EN 60950).
SNMP
Simple Network Management Protocol is an application layer protocol that facilitates the exchange of
management information between network devices. It is part of the Transmission Control Protocol/Internet
Protocol (TCP/IP) protocol suite and is defined in RFC1155.
STB Set-Top Box: A box that sits on top of a television set and is the interface between the home television and the
cable TV company. New technologies evolving for set-top boxes are video-on-demand, video games, educational
services, database searches, and home shopping. The cable equivalent of the IRD.
STT System Time Table (ATSC).
SFN Single Frequency Network: The SFN technique allows large geographic areas to be served with a common
transmission multiplex. All transmitters in the network are synchronously modulated with the same signal and they
all radiate on the same frequency. Due to the multi-path capability of the multi-carrier transmission system
(COFDM), signals from several transmitters arriving at a receiving antenna may contribute constructively to the
total wanted signal. The SFN technique is not only frequency efficient but also power efficient because fades in the
field strength of one transmitter may be filled by another transmitter.