User guide

Appendix E - Glossary E-7
Q
QPSK Quaternary Phase Shift Keying – A modulation technique in which the carrier
is phase shifted +/-90 or +/-180 degrees. See also BPSK.
R
RF Radio Frequency – A generic term for signals at frequencies above those used
for baseband or IF.
RFC Request For Comment – The de-facto Internet standards issued by the Internet
Engineering Task Force (IETF).
RIP Routing Information Protocol
RS-232 A common electrical/physical standard issued by the IEEE used for point to
point serial communications up to approximately 115kb/s.
RS-485 A common electrical/physical standard issued by the IEEE used for multi-drop
serial communications.
Rx Receive
S
SCPC Single Channel Per Carrier – A satellite communications technique where an
individual channel is transmitted on the designated carrier frequency. Some
applications use SCPC instead of burst transmissions because they require guar-
anteed, unrestricted bandwidth.
SMTP Simple Mail Transfer Protocol – A protocol for exchanging e-mail messages
between host computers. See also POP3.
SNMP Simple Network Management Protocol – A protocol defining how devices from
different vendors may be managed using a common network management
system.
SPL Synchronous Party Line – An electrically isolated interface between indoor and
outdoor equipment used in VIPERSAT satellite systems. See also APL.
Star
Topology
A network topology which, if drawn as a logical representation, resembles a star
with a hub at the center.