Comtech EF Data SLM-5650A Vipersat Parameter Editor - Manual (Page 71)

Appendix A - Glossary A-7
NP Network Processor
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.
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
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. Examples are binary phase-shift
keying (BPSK or 2-PSK) which uses two phases, and quadrature phase-shift
keying (QPSK) which uses four phases.
PSTN Public Switched Telephone Network – The world’s public circuit-switched
telephone network, digital and analog, and includes mobile as well as land-line
voice and data communications.