Page 304 - Optical Switching And Networking Handbook

13_200023_Glossary/Bates 1/17/01 10:10 AM Page 289

Glossary 289

Synchronous Transport Signal Level N (STS-N) The signal
obtained by multiplexing integer multiples (N) of STS-1 signals
together.
Terabits per second (Tbps) One trillion bits per second. An
information-carrying capacity measure used for high-speed
optical data systems.
Time Division Multiplexing (TDM) An electrical (digital)
multiplexing technique used to enable multiple streams of
information to share the same transmission media. For trans-
mission at 155 Mbps or above, the electrical TDM signal is
typically converted to an optical signal for transport.
Total Internal Reflection The reflection that occurs when light
strikes an interface at an angle of incidence (with respect to the
normal) greater than the critical angle.
Transmission The process of sending information from one
point to another.
Transparent Optical Networks The original vision of the “all
optical network” as a network in which a signal is transported
from source to destination entirely in the optical domain. After
ingress into the network, the signal is never converted to the
electrical domain for analog operations such as amplification and
filtering or any other purpose.
T1X1 Subcommittee A committee within ANSI that specifies
SONET optical interface rates and formats.
Virtual Tributary (VT) A signal designed for the transport and
switching of sub-STS-1 payloads.
Wide area network (WAN) A data communications facility
involving two or more computers with the computers situated
at different sites.
Wander Long-term variations in a waveform.
Waveguide A material medium that confines and guides a prop-
agating electromagnetic wave. In the microwave regime, a wave-
guide normally consists of a hollow metallic conductor, generally