Information and Communication Technology
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.
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.
Many satellites are needed for GPS to cover all parts of the Earth so that location can be found accurately from anywhere on Earth.
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)
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.
- 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
- It completes one revolution around the Earth in about 90 minutes.
- It is visible over Nepal for about 6–10 minutes during each pass.
- Aavash Maskey
- Hariram Shrestha
- Geographical structures
- Forests
- Glaciers
- Mountains
- Streets and settlements of Nepal
- 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
- 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.
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| 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.| 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)
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| 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.
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
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
- 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
- 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.
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 |







