Comtech EF Data Vipersat Load Utility v3.5.x - Manual (Page 95)

Appendix A - Glossary A-5
H
H.323 A protocol standard for multimedia communications designed to support real-
time transfer of audio (such as voice over IP) and video data over packet
networks. Quality of Service is a key feature of H.323. An alternative to SIP.
HDLC High Level Data Link Control – A standard defining how data may be transmit-
ted down a synchronous serial link.
HPA High Power Amplifier – The amplifier used in satellite communications to raise
the transmit signal to the correct power level prior to transmission to satellite.
HTTP Hyper Text Transfer Protocol – The Internet standard for World Wide Web
(WWW) operation.
Hub The central site of a network which links to a number of satellite earth sites
(Remotes).
I
ICMP Internet Control Message Protocol
IDU Indoor Unit – In a VSAT system, the satellite modem is referred to as the IDU.
IF Intermediate Frequency – In satellite systems, IF frequencies are usually
centered around 70/140 MHz (video/TV), or 1200 MHz (L-band).
IFL Intra-Facility Link – The coaxial cabling used to connect the satellite ODU to
the IDU. Carries the inbound and the oubound signals, and the 24 VDC for the
LNB.
Image A binary firmware file that provides the operational code for the processor(s) in
a network unit.
IP Internet Protocol – A format for data packets used on networks accessing the
Internet.
ISP Internet Service Provider – A company providing Internet access.
ITU International Telecommunications Union