chapter - 13 (Information and communication technology) Flashcards
About ICT.
ICT refers to the technologies that are related to sharing information through telecommunication. Nowadays due to the communication satellite the ICT development have highly raised.
Some examples of ICT.
telephone, television, mobile phone etc.
What is satellite?
Satellites are objects or bodies which revolve around a heavenly body in a fixed orbit. They may be artificial or natural. A satellite doesn’t need any external energy to rotate as there is no friction in the space. It uses solar energy for the computer.
About satellite functions.
Satellites are tested and placed on the orbit of the earth depending on their function. Satellites are used for various purposes like taking photographs of various atmospheric layers, for scientific research and observing the earth.
LEO station
Lower Earth Orbit station is closest to the earth’s surface. ISS (International Space Station) is a lower Earth orbit station which lies 408 km above the surface of the earth. It takes about 90 minutes for a satellite to orbit around the earth.
MEO station
Medium Earth Orbit station is a satellite that lies above LEO but under GEO. This satellite is used for a navigation system which helps to identify the exact location of any object on the earth. This is called GPS or Global positioning system. In this satellite, it takes about 12 hours to orbit around the Earth. And there are about 24 navigation satellites.
GEO station:
(time taken to revolve, function.)
Geostationary Orbit (GEO) station lies above the medium line. This station takes 23 hours 56 minutes and 4 seconds to orbit around the Earth which is same time as the rotational speed of the Earth so these satellites always lie at the same distance from the Earth. These satellites are used for weather forecasting as the view of the earth’s surface is clearly visible and it is also responsible for the functioning of the telephone, mobile phones and the internet.
Nepal Sat I:
Its developer?, Its weight, function, time taken.
Nepal Sat I is the first satellite launched by Nepal. It was a low earth orbit satellite which was made by Abash Maskey and Hari Shrestha. This satellite weighs about 1.33 kg and it was launched from USA, Virginia. This satellite was a low earth orbit satellite, it took 1 hour to revolve around the earth, and it stayed from 6 to 10 minutes above the Nepal. This satellite was mainly used for taking photos of Nepal’s landscapes, forests, rivers etc.
Who developed the fax and when?
Alexander Bain of Scotland developed a fax machine in 1842.
Introduction about Internet.
The Internet is a global networking system which interconnects different networks to share information and knowledge.
Full form of WI-FI
Wireless Fidelity
Introduction about Global Navigation System (GPS).
Global Navigation System, originally a radio-navigation system used by the USA is mainly used for tracking or navigation. It works with the help of satellites.
What is telecommunication?
Telecommunication is sending information or data in any form such as text, sound, video, pictures, etc. from one device to another.
Components of telecommunication.
- Information - Data in form of text or video
- Input transducer- input device
- Transmitter - Electronic device used to send data in waves
- Channel - Media to transfer data such as wires, and waves.
- Reciever
- Output transducer
amplitude modulation.
- In this type of modulation only the amplitude of the carrier wave is changed.
- It has poor sound quality but it can travel to longer distance.
- Its frequency ranges from 535 to 1705kHz
- It is more liable to noise.
Frequency Modulation
- In this type of modulation only the frequency of the carrier wave is changed.
- It has higher bandwidth with better sound quality.
- Its frequency ranges from 88 to 108 MHz.
- It is less liable to noises
search engine
A search engine is a web-based tool that is used by people to find information on the web or internet.
or
A search engine is software designed to carry out information systematically.
search operator
Search Operator or Search Parameter is a character or string of character that are used in search engine query (to ask question) to narrow the focus of the search.
Define firewall
A firewall is a network security system that monitors and controls the incoming and outgoing network traffic based on predefined security rules.
Define computer virus.
A computer virus is a malicious program which is programmed to replicate itself and transfer to other computer and harm the computer and the user.
Symptoms of computer virus
- The computer system becomes slow.
- It may delete files.
- It may take more time to load the program and files.
- It may play unnecessary sound.
Define Antivirus program.
Antivirus is a computer program designed to prevent, detect, scan, and delete the computer virus from the computer.
Examples of antivirus program.
McAfee, Norton-antivirus, Ad-ware etc
