Exam practice

A geostationary satellite goes round the Earth once in the time the Earth turns once, above the equator, so it stays above the same place and seems still in the sky. Dishes on the ground can be pointed at it once and left, and it is always in view, so communication never breaks. From 35,786 km up it can see about two-fifths of the Earth’s surface, so three such satellites, spaced round the equator, can cover almost the whole world (all but the regions near the poles). That makes geostationary orbit ideal for TV, telephone and internet links.

The Earth is round, and high-frequency radio waves (microwaves) travel in straight lines, so a tower on the ground can reach only as far as the horizon, and hills block it. Microwaves pass through the ionosphere instead of being reflected. A satellite high above the Earth can “see” a huge area at once, so a signal sent up to it can be amplified and sent back down over thousands of kilometers, even to other continents.

Information and communication technology (ICT) is the use of electronic devices, such as computers, phones, radio, television and the internet, to store, process and communicate information (sound, text, pictures and video), even to distant places.

A rocket launches the satellite sideways, at right angles to gravity, at a very high speed (about 7.7 km/s at 400 km up). Gravity pulls it towards the Earth, so it keeps falling, but its sideways speed carries it so far that the curved Earth drops away beneath it: it falls around the Earth. There is almost no air up there, so there is no friction to slow it down, and by Newton’s first law it keeps moving. So it needs no fuel to keep revolving. Its solar panels power only its instruments.

NepaliSat-1, a 1.33 kg cube-shaped nanosatellite built by Abhas Maskey and Hariram Shrestha. It was launched on 17 April 2019 and released into orbit from the International Space Station on 17 June 2019.

Telecommunication is sending information (sound, pictures, data) over a distance as signals, through wires, optical fibers or electromagnetic waves. Examples: the telephone, the mobile phone, fax, radio and television broadcasting, the internet, email, Wi-Fi and GPS.

For example:

• talking to relatives and friends by mobile phone, and video calls to family abroad;
• listening to the news and programs on FM radio, and watching TV;
• finding study materials, watching lessons and doing online classes on the internet;
• sending and receiving email and messages;
• finding the way with GPS and a map app;
• paying bills and sending money with mobile banking.

Every telecommunication system has three parts:

1. Transmitter: it turns the input information (from a microphone, camera or computer) into a signal that can be sent, and usually modulates a high-frequency carrier wave with it.
2. Channel: it carries the signal: radio waves, microwaves, a metal cable or an optical fiber.
3. Receiver: it receives the signal, demodulates it, and turns it back into the original form for the user.

Example, FM radio: a presenter speaks into a microphone, which turns the sound into an audio signal. The transmitter amplifies it and uses it to modulate the frequency of a carrier wave (say 100 MHz), and the antenna broadcasts it as radio waves (the channel). A radio set tuned to 100 MHz receives the waves, demodulates them to get the audio signal back, and its loudspeaker turns it into sound.

It is amplitude modulation (AM): the height of the carrier wave rises and falls with the audio signal, while its frequency stays the same.
Purpose: the audio signal on its own is weak and of low frequency, and can’t travel far. Modulation puts it onto a strong, high-frequency carrier wave that can be broadcast over a long distance. AM is used for medium-wave and long-wave radio: its waves are reflected by the ionosphere, so a station can be heard hundreds of kilometers away.

The internet has changed how we communicate, making it faster, cheaper and richer:

• Email has replaced letters and faxes: it arrives in seconds, almost free, with files attached.
• Internet calls and video calls (Viber, WhatsApp, Messenger) let a family in Nepal see and talk to a relative abroad, for the cost of data.
• Online news reaches readers minutes after an event, instead of the next morning.
• IPTV and streaming let us watch programs when we choose, in high quality.
• Social networks let one person share news with thousands at once.

These use computers, smartphones and networks to send text, sound, pictures and video instantly across the world, which older methods could not. So internet communication is a modern communication technology.

• Search engines such as Google find pages on any topic in seconds; search operators narrow the search (for example, photosynthesis filetype:pdf for PDF notes, or site:moecdc.gov.np for CDC’s own materials).
• E-libraries and online encyclopedias (such as Wikipedia, or e-pustakalaya) give books and articles to read for free.
• Educational websites and simulations (such as PhET) and video lessons explain topics with pictures and experiments.
• Online news and government websites give the latest information, such as exam results or weather.
• Email and online classes let us ask teachers and experts questions.

We should check that a source is trustworthy, and name it when we use its material.

Online security means keeping our data, accounts and devices safe from being stolen, damaged or misused when we use the internet.
Ways:

• Use strong, different passwords, and never share passwords, PINs or OTPs.
• Check that a website is genuine and its connection secure (https, padlock, correct address) before entering personal information.
• Don’t click links promising gifts, lotteries or prizes.
• Keep personal information and photos private; don’t accept strangers on social media.
• Keep the firewall on, install antivirus, and keep the computer updated.
• Sign out after use, and don’t save passwords on others’ devices; clear the browsing data.
• Tell a parent or teacher about cyberbullying, keep a record, and report it.

• Never share your PIN, password or OTP, with anyone, even someone claiming to be from the bank. Banks never ask for them; anyone who does is a thief.
• Open banking and shopping sites by typing the address or using the official app, not through links in messages, and check for https and the correct spelling of the address. Fake sites copy real ones to steal details.
• Use a strong, different password for each account, and turn on two-step verification, so one stolen password doesn’t open everything.
• Buy from trusted shops, and prefer cash on delivery or protected payment methods, since fake shops take money and send nothing.
• Keep social media accounts private, accept only people you know, and don’t post your address, travel plans or private photos, which criminals and bullies can use.
• Think before posting: the digital footprint stays.
• Keep your phone and computer updated, with antivirus on, to keep malware out.
• Sign out on shared devices.

Use of Information and Communication Technology in Education

Not long ago, a student in a village in Nepal had a few textbooks, a blackboard, and a teacher’s memory to learn from. Today, a student with a smartphone has the world’s largest library in a pocket. Information and Communication Technology (ICT) is changing how we teach and learn.

ICT brings knowledge to every place. Through the internet, students can read e-books, encyclopedias and the textbooks of the Curriculum Development Centre online, free. Search engines answer questions in seconds. Video lessons and simulations show what words can’t: a heart pumping, a planet orbiting, a chemical reaction.

ICT makes learning interactive. Quizzes, educational games and simulations let students try things for themselves and learn from mistakes. Teachers use projectors and presentations to make lessons lively.

ICT keeps learning going in hard times. During the COVID-19 pandemic, when schools in Nepal closed, lessons continued over radio, television and online classes. Students in remote areas can join classes taught by expert teachers far away.

ICT helps teachers and schools too: teachers share materials and train online, and schools keep records, results and attendance on computers, and contact parents quickly by SMS.

ICT also has problems. Many villages still lack electricity, internet and devices, so the gap between rich and poor students can grow. Too much screen time harms eyes, sleep and health; games and social media distract; and not everything online is true. Students must learn to check sources, respect copyright, and stay safe online.

Used wisely, ICT makes education wider, richer and fairer. With good internet in every school, trained teachers and careful students, it can give every child in Nepal the chance to learn anything.