10 computer notes

 A computer network is a group of two or more computers and devices that are connected to share data, resources, and messages.

Mobile networks like 4G LTE (Long Term Evolution) and 5G make the Internet faster and more reliable. 4G LTE gives better speed for video calls, online classes, and downloading. 5G is even faster,

Telecommunication means sending and receiving information overlong distances with the help of electronic devices.These devices include telephones, mobile phones, radios, televisions, and computers.

To make this communication possible, different devices are connectedtogether.Thisconnection is called a network.

Broadband is a high-speed Internet connection that allows you to send and receive a large amount of data quickly. It is much faster than the old dial-up Internet used inthepast.Therearedifferenttypesofbroadbandconnections,suchas:

i.        DSL(Digital SubscriberLine)–uses telephone lines.

ii.        Cable–uses TVcables.

iii.        Fiber-optic–usesspecialglasswiresforveryhigh speed.

iv.        Satellite–connectsthroughsignalsfromsatellitesin space.

v.        Wireless–usesmobilenetworkslike4GorWi-Fi.

 Throughput means the actual amount of data that is successfully sent or received overanetworkinacertainamountoftime

Throughput is usually measured in:

·         bps–Bitsper second

·         Mbps–Megabitsper second

·         Gbps–Gigabitsper second

Bandwidth is the maximum amount of data that a network can carry in a given time

3G(Third GenerationNetwork)

3G is the third generation of mobile network technology. It was a big improvement over older 2G networks. With 3G, people could use the Internet on their phones more easily and at faster speeds.

3G allows:

i.        Faster Internet browsing

ii.        Sending and receiving pictures and videos(multimedia messaging)

iii.        Making video calls

iv.        Using mobile broadband services like online games and apps

4G(Fourth Generation Network)

4G is the fourth generation of mobile network technology. It is much faster and more reliable than 3G. With 4G, using the Internet on mobile devices became smoother and quicker.

4G offers:

i.        Very fast download and upload speeds

ii.        Low latency (less delay during online activities)

iii.        High-quality video streaming (HDvideos)

iv.        Better online gaming experience

v.        Quick access to websites, apps, and cloud services

5G (Fifth Generation Network)

5G is the fifth generation of mobile network technology. It is much faster, smarter, and more powerful than 4G. It gives very high speed, strong connection, and can support many devices at the same time.

5G helps in:

i.        Super-fast Internet access

ii.        Running advanced apps like Augmented Reality(AR) and Virtual Reality (VR)

iii.        Supporting autonomous vehicles (self-driving cars)

iv.        Connecting smart devices in the Internet of Things(IoT),like smart homes and cities

Data Packets

When we send information over a computer network, it is broken into small parts called data packets. These packets travel across the network and are put back together at the destination.

Data packets help to:

·         Send information faster

·         Make data transfer more reliable

·         Ensure efficient communication over long distances

Frequency

In telecommunication, frequency means how often data signals are sent over a communication channel in one second. It helps decide how fast and clearly signals can travel through the air or wires.

Frequency is important for

i.        Wi-Fi and Bluetooth connections

ii.        Mobile networks like 4G and 5G

iii.        Radio and TV broadcasting

iv.        Devices like micro wave ovens and RFID systems

Frequency is measured in

·         kHz–kilohertz (1,000timesper second)

·         MHz–megahertz (1million times per second)

·         GHz–gigahertz (1billion times per second)

Technology/Use	Frequency Range	Purpose / Use
Wi-Fi(2.4GHz)	2.4 – 2.5 GHz	Wireless internetathomeor school (WLAN)
FM Radio Broadcasting	88 – 108 MHz	PlayingmusicandnewsonFM radio
Microwave Ovens	2.45 GHz	Heating food

Technology/Use	Frequency Range	Purpose / Use
Bluetooth	2.4 – 2.5 GHz	Connectingwirelessdevices (like speakers, earbuds)
AM (Amplitude Modulation) Radio Broadcasting	530 – 1710 kHz	Long-distanceradio,especially at night
5G Cellular (mmWave)	24 – 100 GHz	Veryfastmobilecommunication in short distances
RFID (UHF) Radio Frequency Identification (Ultra-High Frequency)	860 – 960 MHz	Usedinsmartcards,inventory tracking
TelevisionBroadcasting (UHF)	470 – 890 MHz	DigitalTVsignals

Modes of communication:

1. Simplex: Only sender sends information, receiver only receive the message. It is one way communication. Eg, Television, radio
2. Half duplex: Sender sends the data while receiver receive the data and vice-versa. It is the two way communication but one at a time Eg, Walkie-Talkie
3. Full duplex: It is two way communication in which sender and receiver both can send and receive information at same time. Eg, mobile communication. Messanger call, Phone call, Video call.

Communication media is the path or channel used to send data and information between devices in a network. It is also called transmission media. 

There are two types of communication media:

i.             Guided Media – uses physical wires or cables (like twisted pair, coaxial, and fiber optic).

i.                                   CAT6(Category6)–a common cable used for fast Ethernet connections.  

                            Key featuresof CAT6:

i.                                          Supports speeds up to 1 Gbps over 100 meters

ii.                                        Can reach 10Gbps over shorter distances

iii.                                         Has better insulation and tightly twisted wires

iv.                                         Reduces signal interference for a stable connection

    

ii.                                  Optical fiber–a cable made of glass or plastic that transfers data using light. It is very fast                        and  can carry data over long distances.

                           StraightTip(ST), Screw-Mounted Adaptors (SMA), and Subscriber Connector (SC).

ii.             Unguided Media–uses wireles ssignals through air(like Wi-Fi, Bluetooth, radio waves).

           

             Common types of wireless communication are:

i.                                     -Wi-Fi–forwirelessinternet access

ii.                                    - Bluetooth–for short-range device connections.To share data over short distances without                          using any cables. It works using a smart method called Frequency Hopping                                              SpreadSpectrum(FHSS),

iii.                                    -RFID(Radio Frequncy Identification)– for tracking and identification (like IDcards)

                         RFID is widely used in many industries for identifying and tracking items, managing                           inventory, controlling access to secure areas, and even for contactless payment systems.

              - Satellite Communication–for global communication using satellites

                   Satellites work like microwave relay stations in the sky, receiving signals from one place                      and sending them to another. 

     

Guidedmedia	Unguidedmedia
Data and signals are sent through wires or cables.	Data and signals are sent through the air without wires.
Not affected by weather conditions like rain or wind.	Can be affected by weather condi- tions like rain or wind.
Used to connect close devices such as in a Local Area Network (LAN).	Used to connect devices faraway such as in a Wide Area Network (WAN).
Provides a fixed path or direction for data.	No fixed path; data travels freely through the air.
Also called wired or guided media.	Also called wireless or unguided media.
Examples:CAT6cable,Coaxialcable, Optical fiber.	Examples:Wi-Fi,Bluetooth,Micro- wave, Satellite, Infrared.

Connectors are small hardware devices used to connect communication media (like cables) to network devices such as computers, routers, and switches. 

Registered Jack45 (RJ-45):The RJ45 connector is a standardized interface for connecting Ethernet cables to network devices like computers, routers, and switches.eight pins in a modular jack format, easy insertion and removal,

A media converter is a device in computer networks that connects several types of cables such as copper (wired) and fiber optic cables.It operates by converting electrical impulses from copper cables to light signals for fiber optic connections, 

Media converters are useful when: The copper cable is not long enough. Fiber optic cables are needed for faster speed and better performance.

Networking Devices:………All devices in concerns to network like Computer,Switch, Router, RJ45, are called Networking Devices.

Repeater: The repeater is a network connectivity device that accepts weak signals and regenerates them and after that sends the message on its way. 

Hub: Hub is a network connectivity device with multiple ports for connecting different computers on the network.

Switch: The switch is a network connectivity device that joins multiple computers together to share information among them.

Bridge:

The bridge is a network connectivity device that interconnects two computer networks having similar protocols. 

Router:

The router is a network connectivity device that joins multiple wired or wireless networks together. 

Topology: Network topology is the inter-connected pattern of network components. 

The four main types of topology are:

i.            BusTopology

ii.             StarTopology

iii.             RingTopology

iv.            HybridTopology

 BusTopology: a single cable to connect nodes.

                                                                    

It's features : 

It is cost-effective, and the cable required is less compared to other network topologies.

ii.         It is used in small networks and is easy to understand.

iii.          It is easy to expand networks.