8 – Glossary
HD Link Installation & Operation Manual
Version 2, April 2010
Harris Corporation
8-3
Intraplex Products
Reference
Description
RF
Radio frequency; group of electromagnetic energy whose wavelengths are
between the audio and light range. Transmitted electromagnetic waves are usually
between 500 kilohertz and 300 Gigahertz.
Rx Sensitivity
Receiver sensitivity; required receiver level for BER.
SCA
Auxiliary multiplexed channel or channels in a broadcast FM signal, located higher
in frequency than the stereo sub-channel.
Secondary
In a redundant HD Link system, the transmitter or receiver acting as the backup
unit in the redundant system.
SET Request
An snmpset command file sends an SNMP set request to the specified node.
SNMP
Simple Network Management Protocol; a set of standards for communication with
devices connected to a TCP/IP network.
SNR
Signal-to-noise ratio; measurement of the relative level of noise on a circuit and,
therefore, the quality of a transmission; the ratio of the usable signal transmitted
to the noise or undesired signal. If the level of noise is high, data packets have to
be re-sent, slowing down the data transfer and reducing efficiency with which the
circuit and network are used.
Source Quench
An Internet Control Message Protocol message which requests the sender to
decrease the traffic rate of messages to a router or host.
Spectral
Efficiency
Amount of information that can be transmitted over a given bandwidth in a
specific communication system; a measure of how efficiently a limited frequency
spectrum is utilized by the physical layer protocol and sometimes by the media
access control (the channel access protocol).
Standalone
Single HD Link transmitter-receiver pair operating independently rather than in a
redundancy system.
Standby
In a redundant HD Link system, the transmitter or receiver that is not currently
transmitting or receiving signals but ready to do so in case of manual or automatic
switchover.
STL
Studio-to-transmitter link; a communications link used for the transmission of
broadcast material from a studio to the transmitter.
Switchback
In redundancy, the process by which the primary HD Link transmitter or receiver
takes over as Active when either the secondary unit fails or there is a manual
switch.
TCP
Transmission control protocol; the reliable transport protocol within the TCP/IP
protocol suite; TCP ensures that all data arrive accurately and 100% intact at the
other end; TCP is “connection oriented” and requires a handshake before the
session can begin.
UDP
User datagram protocol; a protocol within the TCP/IP protocol suite that is used in
place of TCP when a reliable delivery is not required, such as for streaming media,
Voice over IP (VoIP), and media conferencing; UDP is “connectionless” and just
sends out packets without first using a handshake to start a session.
USB
Universal Serial Bus; most commonly used way of connecting devices to personal
computers.