Comms 2 (PDF) Flashcards
5 components of data communications
- Sender
- Receiver
- Message
- Communication media
- Protocol
Transmission medium is also known as
channel
The capacity of a channel is measured in terms of
bandwidth
range of frequencies available for transmission of data through that channel.
Bandwidth
Number of bits transmitted between source and destination in one second
data transfer rate
It is the data or information that needs to be exchanged between the sender and the receiver
message
It is the path through which the message travels between source and destination
communication media (medium)
It is a set of rules that need to be followed by the communicating parties in order to have successful and reliable data communication
Protocols
Data transfer rate is also known as
bit rate
Two commonly used switching techniques
- Circuit switching
- Packet switching
before a communication starts, a dedicated path is identified between the sender and the receiver. This path is a connected sequence of links between network nodes. All packets follow the same path established during the connection.
circuit switching
each information or message to be transmitted between sender and receiver is broken down into smaller pieces
packet switching
anything that can carry signals or data between the source (transmitter) and destination (receiver)
Transmission medium
2 classification of transmission
- guided
- unguided
there is a physical link made of wire/cable through which data in terms of signals are propagated between the nodes.
guided transmission (wired media)
data travels in air in terms of electromagnetic waves using an antenna
unguided transmission (wireless media)
Any physical link that can carry data in the form of signals
wired transmission media
Consists of two copper wires twisted like a DNA helical structure used for wired transmission
Twisted pair cable
2 types of twisted pair cable
- Unshielded
- Shielded
Better shielded and has more bandwidth than a twisted pair used for wired transmission
Coaxial cable
carries data as light, which travels inside a thin fiber of glass
Optical fibre
Information travels in the form of electromagnetic signals through air
Wireless transmission media
What is the range of the electromagnetic spectrum
3KHz - 900THz
4 categories of electromagnetic spectrum
- Radio
- Microwaves
- Infrared
- Visible (Light)
Frequency range of radio waves
3KHz - 1GHz
Frequency range of microwaves
1Ghz - 300 GHz
Frequency range of infrared waves
300GHz - 400THz
short-range wireless technology that can be used to connect mobile-phones, mouse, headphones, keyboards, computers, etc. wirelessly over a short distance.
bluetooth
Wireless technology that allows you to connect to the internet
Wireless LAN (local area network)
LAN number
802.11 (wifi)
Let’s us control and communicate with other smart devices
Internet of things (IOT)
primary protocol used to access the World Wide Web
HiperText Transfer Protocol (HTTP)
Who led the development of HTTP
Berners-Lee
the protocol used for transferring files from one machine to another.
File Transfer Protocol (FTP)
Protocol that defines how two devices will authenticate each other and establish a direct link between them to exchange data
Point-to-Point protocol (PPP)
It is a set of standardised rules that uses a client-server model of communication in which a user or machine (a client) requests a service by a server in the network
Transmission Control Protocol/ Internet Protocol
