User`s guide

Glossary
MS-4900, Rev. A G-3
Node
mode of operation using a transport protocol that enables packets to be
individually read, error-checked, reassembled, and output as integral blocks
of information. The output blocks are packets of type “extract protocol.”
Used only with WavePhore proprietary software.
nonvolatile memory
portion of the memory that retains information even when power is turned
off; settings stored in nonvolatile memory do not have to be reissued after a
power interruption unless a change to an operating parameter is required.
PAD
Packet Assembler-Disassembler . A mode of operation using a transport
protocol that outputs data in the same format and order in which it was sent.
PSK
Phase Shift Keying. Form of modulation used to impress information onto an
RF carrier for transmission from one location to another
PVC
Permanent Virtual Circuit. A dedicated communications circuit that allows
for continuous data transmission. Contrast with TVC, that requires each
transmission session to be opened, then closed when the session ends.
packet
Contains data and processing information such as the source of the data, the
length of the message, and its destination. Packets must be statistically
demultiplexed in the IDR V1000 before the message can be processed and
output.
partition
Segment of an aggregate data stream. In the IDR V1000, the aggregate data
stream is extracted into four partitions: the transparent asynchronous or stat-
muxed data that is sent to the processor, two transparent synchronous data
streams that are sent to Serial 4 and 5, and a network control channel that
contains only internally-used control commands.
propagation delay
the delay from the time a signal is sent until it is received.
QPSK
Quadrature Phase Shift Keying. Phase shift keying in which four discrete
phases of the RF carrier are used, each differing by 90 degrees from the next.
Each set of four phases represent two consecutive bits of the data stream.
Reed-Solomon
codec
block-oriented coder/decoder hardware that is applied on top of standard
Viterbi coding to correct most data errors that are not detected by the other
coding systems; significantly reduces the bit error rate. (Available in IDR
V1000 model 1216 systems)
RS-232
an Electronic Industries Association (EIA) standard for low-speed,
asynchronous and synchronous transmission
RS-422
an EIA standard for synchronous transmission
RF
Radio Frequency
SCPC
Single Channel Per Carrier.