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MultiFRAD 3000-Series User Guide
Signaling: The process of establishing, maintaining, accounting for, and terminating a connection between two endpoints (e.g., the
user premises and the telco CO). Central office signals to the user premises can include ringing, dial tone, speech signals, etc. Signals
from the user's telephone can include off-hook, dialing, speech to far-end party, and on-hook signals.
In-band signaling techniques include pulse and tone dialing. With common channel signaling, information is carried out-of-band.
Simple Network Management Protocol (SNMP): TCP/IP protocol that allows network management.
Simultaneous Voice Data (SVD): A technology for letting a user send data via a modem, and use a handset to talk to another user at
the same time over the same connection. The alternative, making a second call, can be expensive or even impossible. The uses for
SVD are telecommuting, videoconferencing, distant learning, tech support, etc.
Stop Bit: One of the variables used for timing in asynchronous data transmission. Depending on the devices, each character may be
trailed by 1, 1.5, or 2 stop bits.
Superframe (D4): A T1 transmission format that consists of 12 DS1 frames, or 2316 bits. A DS1 frame consists of 193 bit positions. A
frame overhead bit is in the first position, and it is used for frame and signaling phase alignment only.
Subscriber Loop: See "Local loop".
Switched 56: A circuit-switched (full duplex digital synchronous data transmission) service that lets you dial a number and transmit data
to it at 56K bps. It is a relatively low cost service, widely used in North America for telecommuting, videoconferencing and high speed
data transfers. Many phone companies are (or will be) phasing out Switched 56 in favor of ISDN service.
Switched Virtual Circuit (SVC): A type of data transmission where the connection is maintained only until the call is cleared.
Switched Line: In communications, a physical channel established by dynamically connecting one or more discreet segments. This
connection lasts for the duration of the call after which each segment may be used as part of a different channel. Contrast with leased
line.
Switched Network: A network in which a temporary connection is established from one point via one or more segments.
Synchronous Data Link Control (SDLC): A discipline conforming to subsets of the Advanced Data Communications Control Proce-
dures (ADCCP) of the American National Standards Institute (ANSI) and High-level Data Link Control (HDLC) of the International
Organization for Standardization, for managing synchronous, code-transparent, serial-by-bit information transfer over a link connection.
Transmission exchanges may be duplex, or half-duplex over switched or nonswitched links. The configuration of the link connection may
be point-to-point, multipoint, or loop.
Synchronous Transmission: The transmission of data which involves sending a group of characters in a packet. This is a common
method of transmission between computers on a network or between modems. One or more synchronous characters are transmitted to
confirm clocking before each packet of data is transmitted. Compare to Asynchronous Transmission.
Systems Network Architecture (SNA): The description of the logical structure, formats, protocols, and operational sequences for
transmitting information units through, and controlling the configuration and operation of of, networks.
T
Tariff: The rate/availability schedule for telephone and ISDN services from a regulated service provider.
TCP/IP: A set of communication protocols that support peer-to-peer connectivity functions for both local and wide area networks.
T Carrier: The generic name for a digitally multiplexed carrier system. In the North American digital hierarchy, a T is used to designate
a DS (digital signal) level hierarchy. Examples: T1 (DS1) is a 1.544 M bps 24-channel designation. In Europe, T1 is called E1. The T
Carrier system was originally designed for transmitting digitized voice signals, but has since been adapted for digital data applications.
T1: A digital transmission link capable of 1.544M bps. T1 uses two pairs of normal UTP, and can handle 24 voice conversations, each
digitized at 64K bps. T1 is a standard for digital transmission in the U.S., Canada, Japan and Hong Kong. T1 is the access method for
high-speed services such as ATM, frame relay, and SMDS. See also T Carrier, T1 line and FT1.
T1 Channel Tests: A set of diagnostics that vary by carrier, used to verify a T1 channel operation. Can include Tone, Noise Level,
Impulse Noise Level, Echo Cancellors, Gain, and Crosstalk testing.
T1 Framing: To digitize and encode analog voice signals requires 8000 samples per second (twice the highest voice frequency of 4000
Hz). Encoding in an 8-bit word provides the basic T1 block of 64K bps for voice transmission. This "Level 0 Signal, as its called, is
represented by "DS-0", or Digital Signal at Level 0. 24 of these voice channels are combined into a serial bit stream (using TDM), on a
frame-by-frame basis. A frame is a sample of all 24 channels; so adding in a framing bit gives a block of 193 bits (24x8+1=193).
Frames are transmitted at 8000 per second (the required sample rate), creating a 1.544M (8000x193=1.544M) transmission rate.
T1 Line: A digital communications facility that functions as a 24-channel pathway for data or voice. A T1 line is composed of two
separate elements: the Access element and the Long Haul element.