User guide

Appendix I - Glossary I-7

QPSK Quaternary Phase Shift Keying – A modulation technique in which the carrier

is phase shifted +/- 90 or +/-180 degrees. See also BPSK.

QoS Quality of Service

Remote Satellite earth site that links to a central network site (hub).

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 115 kb/s.

RS-485 A common electrical/physical standard issued by the IEEE used for multi-drop

serial communications.

Rx Receive

SCPC Single Channel Per Carrier – A satellite communications technique where an

individual channel is transmitted to the designated carrier frequency. Some

applications use SCPC instead of burst transmissions because they require guar-

anteed, unrestricted bandwidth.

SNMP Simple Network Management Protocol – A protocol defining how devices from

different vendors may be managed using a common network management

system.

SOTM Satellite On The Move

SPL Synchronous Party Line – An electrically isolated interface between indoor and

outdoor equipment used in Vipersat satellite systems. See also APL.