Unit 13

Information and Communication Technology

Information and communication technology is a medium which can store large amount of information, process data and communicate information by the help of electronic devices.

To communicate information over long distances quickly, ICT uses advanced technologies such as artificial satellites.

- Artificial satellite: Artificial satellite is defined as a body placed in orbit round the earth or moon or another planet in order to collect information or for communication.

- The first artificial satellite in the world was Sputnik-1 launched by Soviet Union on October 4, 1957.

Q. How are artificial satellites launched and maintained in orbit around the Earth?

Artificial satellites are launched using rockets and placed at a fixed height and speed so that Earth’s gravity keeps them moving in orbit. Since there is almost no air in space, satellites do not need extra energy to keep moving.

- Orbits of artificial satellite: Based on height and purpose, satellites are placed in three main orbits.

[A] Low earth orbit (LEO): Low Earth Orbit (LEO) is an orbit around the Earth at an altitude between about 180 km and 2,000 km above the Earth’s surface. Example of satellite in this orbit are ISS (international space station), Nepali sat-1 etc.

The satellites placed in LEO possesses following characteristics:

· Satellites revolve very close to the Earth

· They have a very high orbital speed

· They complete one revolution in a short time (about 90 minutes)

· They remain above a particular place on Earth for a short duration

· One satellite can observe many different places in a single day

Q. How can LEO satellites observe many places in one day?

LEO satellites revolve very fast around the Earth and continuously change their position. Due to this, they can observe many different places on Earth in a single day.

[B] Medium earth orbit (MEO): Medium Earth Orbit (MEO) is the region of space between Low Earth Orbit and Geostationary Earth Orbit, at an altitude of about 2,000 km to 35,786 km above the Earth’s surface. Examples of satellite in this orbit are navigation satellites, GPS satellites etc.

The satellites placed in MEO possesses following characteristics:

· Satellites revolve at a moderate distance from the Earth

· Their orbital speed is slower than LEO satellites

· The time period of revolution is about 12 hours

· Each satellite covers a large portion of the Earth

Q. Why are many satellites needed for GPS?

Many satellites are needed for GPS to cover all parts of the Earth so that location can be found accurately from anywhere on Earth.

[C] Geostationary earth orbit (GEO): Geostationary Earth Orbit (GEO) is a special orbit at an altitude of 35,786 km above the Earth’s equator.

Characteristics of satellites placed in GEO:

· Satellites revolve above the equator

· The time period of revolution is exactly equal to Earth’s rotational period (23 h 56 min 4 s)

· Satellites appear stationary relative to the Earth

· One satellite can continuously cover the same area of Earth

Q. Why do GEO satellites look stationary?

GEO satellites look stationary because they revolve around the Earth with the same speed as the Earth’s rotation.

Q. Why have many countries of the world launched communication satellites in geostationary orbit?
Many countries place communication satellites in geostationary orbit because these satellites appear stationary relative to the Earth. This allows them to provide continuous and reliable communication to the same area without needing to constantly track their position.

- Uplink and Downlink (Satellite Communication)

Communication between Earth and satellite happens using microwaves:

Uplink: Signal sent from ground station → satellite

Downlink: Signal sent from satellite → Earth

The satellite receives the signal, amplifies it, and sends it back.

Q. Why are satellites useful for communication?

Satellites are useful for communication because they can receive signals from one place and transmit them quickly to very far places on the Earth quickly.

NepaliSat-1 (First Satellite of Nepal)

NepaliSat-1 is the first artificial satellite of Nepal. It is an important achievement for Nepal in the field of space science and technology.

Basic Information

Type: Cube nano-satellite
Mass: 1.33 kg
Launch date: April 18, 2019
Launch place: Virginia, USA
Orbit: Low Earth Orbit (LEO)
Height from Earth: About 400 km

Motion and Visibility

It completes one revolution around the Earth in about 90 minutes.
It is visible over Nepal for about 6–10 minutes during each pass.

Constructed By

Aavash Maskey
Hariram Shrestha

Purpose of NepaliSat-1

The main purpose of NepaliSat-1 is to take photographs of Nepal from space. These photographs help in studying:

Geographical structures
Forests
Glaciers
Mountains
Streets and settlements of Nepal

Importance

Helps Nepal enter satellite technology
Provides useful geographical data
Develops scientific and technical skills

Use of Information & Communication Technology:

Magazine: Used to gain general knowledge and information about current events.
Radio: Used to receive news and educational programs quickly over long distances.
Television: Used to watch educational programs and live events happening around the world.
Telephone: Used to communicate voice messages instantly with people at distant places.
Fax: Used to send printed documents and pictures from one place to another.
Mobile Phone: Used to communicate wirelessly through calls, messages, and internet services.
Internet: Used to search information related to study and daily life.
Wi-Fi: Used to connect devices to the internet without using wires.
GPS: Used to find the exact location and direction of a place.

Telecommunication

- Telecommunication is a system in which a communication signal is transferred from one place to another using various types of technologies through wire, optical fiber, wave etc.

- Example: Telephone, fax, mobile phone, internet broadcasting through radio and television etc.

- A basic telecommunication system has following three parts:

i) Transmitter:

Receives the input information (voice, image, data)
Converts it into an electrical signal
Produces the broadcasting signal
Examples of transmitter devices: Microphone, Camera, Computer transmitter unit etc.

ii) Broadcasting channel: This is the medium through which the signal travels. Channels may be: Radio waves, Microwave beams, Metallic cables, Optical fiber etc. The signal is carried from transmitter to receiver through the channel.

iii) Receiver: It receives the transmitted signal and converts it back into useful form (sound, picture, data). Examples of receivers: Antenna, Radio set, Television, Mobile phone etc.

- In flow diagram: (VVI)

Telecommunication system flow diagram showing input signal, transmitter, broadcasting channel, receiver and output signal

Figure: Working principle of telecommunication system (Input → Transmitter → Channel → Receiver → Output)

Modulation and Demodulation

- Modulation is defined as the process of superimposing a low-frequency signal on a high-frequency carrier signal to travel it to a longer distance.

- Demodulation is defined as the process of recovering the original information-carrying signal from a modified carrier wave.

- Difference between Amplitude Modulation and Frequency modulation:(VVI)

Basis	Amplitude Modulation (AM)	Frequency Modulation (FM)
Meaning	The amplitude of the carrier wave is changed.	The frequency of the carrier wave is changed.
Parameter Changed	Amplitude varies, frequency remains constant.	Frequency varies, amplitude remains constant.
Noise Effect	More affected by noise and disturbance.	Less affected by noise, clearer signal.
Sound Quality	Lower sound quality.	Better sound quality.
Use	Used in AM radio broadcasting.	Used in FM radio and TV sound transmission.

Q. Identify the modulation for broadcasting radio wave in the given figure. Write the purpose of such modulation. (VVI)

Amplitude modulation diagram showing audio signal, carrier wave and modulated AM wave Class 9 ICT

This figure explains how amplitude modulation is used to transmit audio signals in radio communication.

Ans: The modulation used for broadcasting radio waves in the given figure is Amplitude Modulation (AM).

Purpose of such modulation:

To transmit low-energy information signals (sound) over long distances.
To convert the message signal into a form suitable for radio-wave transmission.
To make communication possible through a broadcasting channel efficiently.

Q. ‘Internet communication is a modern communication technology.’ Clarify this statement with examples.

Answer:
Internet communication is a modern communication technology because it allows people to exchange information very quickly through the world’s largest computer network. Using internet service, we can connect computers and smartphones and receive information from internet-connected devices. It is widely used today for modern communication and online services.

Examples of internet communication:

Sending and receiving messages through email
Searching learning materials using search engines like Google, Yahoo, and Bing
Using internet applications for communication and entertainment
Accessing different online services easily

Thus, internet communication is called modern communication technology because it is fast, reliable, and widely used in daily life.

Q. How do we get knowledge and information by the use of internet? Explain with examples.

Ans: The internet helps us to get knowledge and information very quickly. We can search and learn many things using the internet.

Examples:

Searching study materials on Google
Reading news and useful information online
Sending messages through email

Thus, the internet is a modern and useful way to gain knowledge.

- Search Engine: It is a software system which searches the information contained in a webpage from the internet and presents all the relevant information searched by a person. Eg: Google, Bing etc.

- Online Security: Online security is defined as step taken by people to secure their networks and computers connected to the internet.

-For the sake of Online security, following measures can be taken:

Use strong, unique passwords and enable MFA/2FA for extra protection.
Keep your software updated
Watch out for phishing emails or links
Use a VPN on public Wi-Fi to secure your data

-Cyberbullying: Cyberbullying is defined as the activity which create mental tension by using electronic devices like mobile, phone, computer, tablets etc by the medium of internet. Eg: Harassment of publishing personal information, spreading rumors about person online etc.

- Following measures can be taken to protect people from cyberbullying:

We shouldn't accept unknown persons friend request in social media.
Personal things and private information shouldn't be shared while we talk and send messages.
Photos and other information shared in social media needs to be secure.
If any person starts the activities of cyberbullying, we should inform guardians or Police.

- Digital footprint awareness:Digital footprint is data evidence generated in various electronic devices while using internet.

Q. Why should we clear cache and browsing history, and why should we avoid saving passwords on other devices?

Ans: The details of the websites remain safe in the devices, which use the internet facilities. Similarly, the password also can remain saved. To remove such data we need to clear cache files opening history of the browser. We should not click the save button if the notification "Do you want to save password?" comes in other devices except personal devices. If a password is saved, it might be misused through the data collector.

Difference between Firewall and Antivirus

Firewall	Antivirus
A firewall protects the computer by controlling incoming and outgoing network traffic.	Antivirus protects the computer by detecting and removing viruses and malware.
It acts as a security wall between the computer and the internet.	It scans files and programs to find harmful software.
It mainly prevents unauthorized access from hackers.	It mainly prevents damage caused by viruses, worms, and trojans.
Example: Windows Firewall	Example: Avast, Norton Antivirus, Kaspersky