Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 541)

Appendix H - Glossary H-9
MN/22156, rev 12
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.
PUM Periodic Update Message – A packet message that is sent by newer Vipersat
modems (e.g., CDM-840) to the VMS every sixty seconds, providing either
registration request or status update and operating parameter information
(SUM).
Q
QAM Quadrature Amplitude Modulation – A digital modulation technique in which
the amplitude of two carrier waves is changed to represent the data signal. These
two waves are 90 degrees out of phase with each other.
QoS Quality of Service
QPSK Quadrature Phase Shift Keying – Sometimes referred to as 4-PSK, or 4-QAM.
A modulation technique in which the carrier is phase shifted +/-90 or +/-180
degrees. With four phases, this modulation can encode two bits per
symbol—twice the rate of BPSK. However, it also uses twice the power. See
also OQPSK and BPSK.
R
Remote Satellite earth site that links to a central network site (Hub).
REST REpresentational State Transfer – An architectural style of large-scale
networked software that takes advantage of the technologies and protocols of
the World Wide Web. REST describes how distributed data objects, or
resources, can be defined and addressed, stressing the easy exchange of infor-
mation and scalability.
RESTful The VMS RESTful interface is a Web Services API that adheres to the REST
principles. This interface provides a high level control of VMS element struc-
tures via document-addressable URL’s simplifying and standardizing on an
external application interface, such as to/from a network management system
(NMS).
Return Path Transmission path from a Remote site to the Hub site.