L7- Building Telecommunication System (Part 2) Flashcards
Most of the lines in the telephone systems of the world at present are _______. Signals are transmitted as continuous waves. This is a satisfactory way to transmit voice.
Analog
The conversion of data from digital form into analog for transmission and then back into digital at the receiving end is done by a pair of interface devices
called
modems (modulator-demodulator)
Modem-based telecommunications have created a significant bottleneck in an environment where computer and peripheral speeds have increased dramatically. The solution is end-to-end __________ communications, in which signals are sent as streams of on/off pulses.
digital
Digital lines are capable of much faster communication and ______________ is now cheaper than analog. All the new equipment now installed in telephone networks is indeed digital.
digital circuitry
Trend: There is a shift toward digital telecommunications is taking place throughout the world. A digital system for telecommunications, called _____________, is in wide use in parts of the telephone network.
TI carrier
Future: ________________ - a completely digital telecommunications network standardized by an international committee.
Integrated Services Digital Network (ISDN)
With the geographical distribution of information systems, increased volumes of transmission, and the move to multimedia, the costs of telecommunications are a significant business concern. Two principal
methods of reducing these costs are:
- Multiplexing - the sharing of a high-capacity link by a number of transmissions
- Signal Compression - using the link more efficiently by removing redundancies from the signal.
Many individual transmissions can share a physical channel through a variety of techniques collectively called ______________. It combines several lower-capacity transmissions into a single transmission, which is split at the receiving end.
Multiplexing
It is the reduction of the need for channel capacity by
removing redundancies from the signal.
Signal compression
________________ differ in scope from relatively slow wide area networks, employed to transmit messages across vast geographic distances, to very fast local area networks that may connect computers located in the same building.
Computer networks
Computers, switches, and terminals interconnected by network links are collectively called _____
nodes
The purpose of network control is to provide a connection between nodes that need to communicate. The arrangement of nodes and links in a network is called a ______
topology
The following network topologies are the most widely used:
- Hierarchical Network
- Star Network
- Ring Network
- Bus Network
This topology matches the organizational structure of
many firms and is still frequently used in WANs. The user workstations may be, in turn, interconnected
using one of the LAN topologies.
Hierarchical Network
In this topology, a hub computer or switch (such as a PBX) interconnects a number of workstations. . The computer at the hub acts as the network server, providing access to the shared database and software. All communications between the workstations must go through this central mode.
Star Network
The nodes are usually close to one another;
this topology is frequently used in LANs. When one node sends a message to another, the message passes through each intermediate node, which restores the signal, as signals deteriorate in transmission.
Ring Network
