ADTRAN 1200051L6 - Manual (Page 156)

Glossary
142 ISU 2x64 Dual Port ISDN Service Unit User Manual 61200051L1-1D
synchronous
1. The condition occurring when two events happen in a specific time relationship
with each other, both under control of a master clock. 2. A method of data trans-
mission requiring the transmission of timing pulses to keep the sender and receiv-
er synchronized in their communication used to send blocks of information.
Synchronous data transmission is used in high-speed data circuits because there is
less overhead than asynchronous transmission of characters which contain two ex-
tra bits per character to affect timing.
T1
Also T-1. A digital transmission link with a capacity of 1.544 Mbps. T1 uses two
pairs of normal twisted wires. T1 normally can handle 24 voice conversations with
each conversation being digitized at 64 kbps. With more advanced digital voice
encoding techniques, it can handle more voice channels. T1 is a standard for digi-
tal transmission in North America.
TA
Terminal Adapter. A DCE that connects to the ISDN S-Interface and enables non-
ISDN terminal equipment to communicate over ISDN.
TE1
terminal equipment type 1. ISDN-compatible terminals.
TE2
terminal equipment type 2. Non-ISDN terminal equipment linked at the EIA-232,
RS-449, or V.35 interface.
transmission
The dispatching of a signal, message, or other form of intelligence by wire, radio,
telegraphy, telephony, facsimile, or other means. A series of characters, messages
or blocks including control information and user data. The signalling of data over
communications channels.
transmission level
The power of a transmission signal at a point of a transmission facility. It may be
measure in absolute terms (dBm) or in a ratio to its level at some reference point
(dB).
twisted pair
Two wires twisted around each other to reduce induction (interference) from one
wire to the other. Several sets of twisted pair wires may be enclosed in a single ca-
ble. Twisted pair is the normal cabling from a Central Office to your home or of-
fice, or from your PBX to your office phone. Twisted pair wiring comes in various
thicknesses. As a general rule, the thicker the cable is, the better the quality of the
conversation and the longer cable can be and still get acceptable conversation qual-
ity. However, the thicker it is, the more it costs.