Advantech L-Band Satellite Modulator Especificaciones descargar pdf (Pagina 88)

Glossary

Term Description

QPSK Quadrature Phase Shift Keying: A modulation technique used to

communicate data over long distances by altering the phase of a

carrier signal according to the four data states. Sometimes known as

quaternary or quadriphase PSK, 4-PSK, or 4-QAM.

RF Radio Frequency.

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 bit-stream by

replacing repeated characters with an instruction of the form ‘repeat

character x y times’.

RX Receive or Receiver.

SCPC Single Channel Per Carrier. Use of a single signal at a given frequency

and bandwidth. Most often, this is used on broadcast satellites to

indicate that radio stations are not multiplexed as subcarriers onto a

single video carrier, but instead independently share a transponder. It

may also be used on other communications satellites, or occasionally on

non-satellite transmissions

Scrambling Alteration of the characteristics of a television signal in order to prevent

unauthorised reception of the information in clear form.

SDI Serial Digital Interface.

SELV Safety Extra Low Voltage (EN 60950).

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.

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.

SNG Satellite News-Gathering.

SNMP Simple Network Management Protocol. A ‘layered’ protocol used in

software applications that facilitates the exchange of management

information between network devices. It is part of the Transmission

Control Protocol/Internet Protocol (TCP/IP) protocol suite. SNMP enables

network administrators to manage network performance and resolve

network problems.

B-10 SBM75e Series Modulator Installation and Operation Manual

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