ITEC102 (SIr Jonel) Flashcards
The transfer of data or information from one location to another
Data Communication
ELEMENTS OF DATA COMMUNICATION SYSTEM
Transmitter or sender or source
Receiver or sink or destination
Medium
Message
The computer or device that is used for sending the data from one location to other
Transmitter
The computer or device that receives the data
It is also known as ‘sink’
Receiver
The path or link through which data transferred from sender to receiver
Medium
The data or information which is sent from sender to receiver
It is the main element of data communication system, due to which data communication occur.
Message
There are two main categories of data communication media:
Guided Media
Unguided Media
are the physical links through which signals are transferred. These are also called bounded media. These include various types of cables. The type of cable chosen for a network depends upon the network’s topology,size and speed.
Commonly used guided media include coaxial cables, wire pairs and fiber-optic cables.
GUIDED MEDIA
are the logical links through which signals are transferred. These are the natural parts of environment that can be used to transfer signals in the form of waves. The atmosphere and space are examples of unguided media.
Commonly used methods of transmission through unguided media are microwave and satellite transmission.
UNGUIDED MEDIA
The manner in which data is transmitted from one location to another
data transmission mode
three different modes for transmitting data from one location to another.
Simplex Mode
Half Duplex Mode
Full Duplex Mode
data is transmitted in only on direction. A terminal can only send data and cannot receive data or it can only receive data but cannot send it. In this mode, the flow of information is uni-directional. It is not possible to confirm successful transmission of data. So it is rarely used for data communication.
This mode is normally used for Remote control devices in which one device can only send data and other can only receive data
SIMPLEX MODE
data can be transmitted in both directions, but only in one direction at a time. Therefore data can be sent and received alternatively. Its disadvantage is that a lot of time is wasted in changing direction of flow of data. So, the transmission rate for this mode is slow.
Use: It is possible to confirm the transmission of data in this mode. So this is normally used in wireless communication system.
HALF-DUPLEX MODE
data can be transmitted in both directions at the same time. In this mode, no time is wasted in changing direction of flow of data like Half-duplex mode. Therefore it is the fastest and most efficient mode.
Use:
Telephone communication
FULL-DUPLEX MODE
The transfer of any kind of information from
one location to another.
DATA TRANSMISSION
means sending a stream of
bits or bytes from one location to another via
transmission medium such as copper wire,
fiber optics, laser, radio,infra red light,
Bluetooth.
Communication
most basic information unit used in
computing & information theory
Bit
a series of 8 bits, also called a
character.
Byte
reads & writes information in bits
Computer
electric or electromagnetic
representation of data.
Can be coded for security purposes.
Signals
converts a message into a signal,
which is carried to a receiver by the communication channel.
Transmitter
2 types of signals;
Analog Signal
Digital Signal
are continuous electrical signals that vary with
time & represented by a waveform.
All natural signal around us is of this type.
ANALOG SIGNAL