ND SatCom SKYWAN IDU 7000, Manual

Page: 149 / 154

2010-10-26 Network Design and Engineering Guide 145
Appendix C - Glossary
Port 1. is normally used for the physical aspect of the systems
boundary or 2. is defined as (logical application) port : i.e. port
21 for FTP. See also Interface.
Propagation Delay The time it takes for a signal to go from the sending station
through the satellite to the receiving station. This propagation
delay for a single hop satellite connection is very close to 240
ms. See also Processing Delay and Latency.
Processing Delay The cumulative delay in a packet-switched satellite network
caused by hardware and software. See also Propagation De-
lay and Latency.
Quadrature Phase Key
Shifting (QPSK) QPSK phase shift modulation involves four levels of phase
shift and encodes two bits per symbol. See also 8-PSK and
Symbol Rate.
Quality of Service (QoS) Provides priority and guarantees a certain level of network re-
sponse time and other performance factors for each applica-
tion and user.
Rain Fade Decrease of satellite signal strength due to rainfall.
Reference Burst Burst sent from the Sky WAN
®
master IDU containing TDMA
network management information like the frame plan.
Request Burst Burst sent from the Sky WAN
®
slave stations to the master to
request network resources.
Satellite Communications satellites orbit the earth in geostationary orbit
and transmit and receive radio frequency signals from VSAT
earth stations.
Satellite news gathering
(SNG) Is typically done from a transportable unit (truck or mobile en-
tity) to transmit video and voice feeds to the studios.
Single Channel Per Carrier
(SCPC) A satellite access method that dedicates one channel to each
remote site, sometime used for very high capacity links. See
also TDMA.
Signal to Noise Ratio (S/N) The ratio of the signal power and noise power. The higher the
number the better the quality.
Single hop Transmission of information from one remote site to another
antenna. Typically it describes the path between two remote
stations in a mesh network without having to go via a hub (dou-
ble hop).
Slave Any Sky WAN
®
IDU which is not assigned the active master
role.
SkyNMS ND SatCom’s Network Management System for central config-
uration, operation and monitoring of
Sky WAN
®
networks.
Term Definition