Comtech EF Data CDM-570/570L Vipersat - Manual (Page 186)

E-8 Vipersat CDM-570/570L User Guide
NOC Network Operations Center – The main control center for network operations.
A NOC can interrogate, control, and log network activities for the satellite Hub
as well as any Remote node.
NP Network Processor – Also referred to as the IP Module. An optional assembly
for Comtech EF Data modems that provides the 10/100 BaseT Ethernet inter-
face that is required when used in Vipersat networks.
O
ODU Outdoor Unit – In a VSAT system, the RF components (transceiver) are usually
installed outdoors on the antenna structure itself and are thus referred to as an
ODU. The ODU typically includes the BUC and LNB, and is connected to the
IDU/modem by the IFL cabling.
OQPSK Offset Quadrature Phase Shift Keying – A variant of phase-shift keying using
four different values of the phase to transmit. Offsetting the bit timing limits the
phase shift and yields lower amplitude fluctuations as compared to QPSK, and
is sometimes preferred for communications systems. See also QPSK and BPSK.
OSPF Open Shortest Path First – An open standard interior gateway routing protocol
used to determine the best route for delivering the packets within an IP network.
OSPF routers use the Shortest Path First link state algorithm to calculate the
shortest path to each node in the network. The Vipersat OSPF feature in the
Comtech SLM-5650A modem/router provides for dynamic routing functional-
ity.
P
PIR Peak Information Rate – The bandwidth available for use by any remote termi-
nal on best effort basis, categorized through multilevel prioritization.
PLDM Path Loss Data Message – A packet message that is sent by older Vipersat
modems (e.g., CDM-570/L) to the VMS every sixty seconds, providing status
update and operating parameter information.
PSK Phase Shift Keying – A digital modulation scheme that conveys data by chang-
ing the phase of a base reference signal, the carrier wave. Different PSKs are
used, depending on the data rate required and the signal integrity. Examples are
binary phase-shift keying (BPSK or 2-PSK) which uses two phases, and quadra-
ture phase-shift keying (QPSK or 4-PSK) which uses four phases.