Windows Desktop Elements and Start Menu Options

Once you are logged in a window computer system, you will get dozens of applications, so you can choose an option of your requirement.

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Many of the options have shortcut icon readily available on your computer screen; however, in some computers, you may not find any such option on the screen; in such a case, you can take the help of menu button (as shown in the image given below) −

Windows Desktop Elements
Windows Desktop Elements

As you can see in the above image, in the left bottom, there is a window symbol (i.e., menu button); once you click on it, the given menu option will appear and from here you can choose your option.

Start Menu Options

The following table lists down the options that appear after clicking on the Start menu −

Sr.No. Option & Description
1

All programs

It displays all those programs, which are installed in your system.
2

Document

It displays a list of folders used by the user.
3

Recent file

It displays the recently used file.
4

My picture

It displays a list of pictures.
5

My music

It displays a list of music/song, etc.
6

My computer

It displays the drives of computer where user keeps his/her work, file, folder, song, video, picture, e-book, etc.
7

Control panel

It displays all the installed computer programs (software).
8

Printer

It displays the installed printers (if printer is installed in the system, user can take print easily).
9

Help (support)

It helps users to know how to do a particular task.
10

Search

It helps a user to find a file in computer.
11

Run

It helps to start an application program or execute a DOS command.
12

Setting

It has different options that help to manage different settings of the computer, software as well as hardware.
13

Log Off

It helps a user to log off the currently logged in user of the system.
14

Sleep

It makes the system non-functional; however, puts the ongoing work and settings in memory and also keeps drawing small amount of power.
15

Hibernation

Hibernation puts the open documents and programs on hard disk and then turns off your computer; in comparison to ‘sleep’, it uses very low power.
16

Restart

Its function is to shut down and again start (log on) computer; it is done normally to refresh computer especially when computer is hanged.
17

Shut down

It simply shuts down the system.

Note − Depending on the version of your window, the menu option may vary in terms of appearance and number of menu options; however, there would not be any change in basics.

Recycle Bin

Recycle Bin is a trash location where deleted files remain stored. Once you delete any sort of file, it gets stored (automatically) into recycle bin; therefore, if you mistakenly deleted some important file, don’t panic, go to recycle bin and restore it. However, if you deleted file from recycle bin as well, then it is very difficult to restore that permanently deleted file.

Recycle Bin
Recycle Bin

Internet Option

The option (i.e., short-cut key) of the Internet browser may be available on the main screen or at the bottom menu bar (as shown in the image given below). However, if do not find it at both these places, go to the menu, as all programs are listed there.

Internet Option
Internet Option

How the Computer Multimedia works.

In this chapter, we will discuss how the Computer Multimedia works. If a system presents, some information through more than two media, it is known as multimedia. For example, TV presents audio and video; book presents text, image, and graphs, computer, etc.

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The information presented through multimedia has better quality and capability, as it can be understood easily.

Computer Multimedia
Computer Multimedia

The advanced computer system is a great example of modern multimedia.

Literal Meaning of Multimedia

In this section, we will understand the literal meaning of multimedia.

  • Multi − it means more than one

  • Medium − it is singular and it means intermediary or mean

  • Media − it is plural and it means conveying the information

Likewise, Multimedia is the field of Computer Science that integrates different forms of information and represents in the form of audio, video, and animation along with the traditional media, i.e., text, graphics/drawings, images, etc.

Multimedia Computer System

Multimedia computer system has high capacity to integrate different media including text, image, graphics, audio, and video.

The multimedia computer system stores, represents, processes, manipulates, and makes available to users.

Significant Features of Multimedia Computer System

Following are the major features multimedia computer system −

  • Its Central Processing Unit (CPU) is very fast, as it needs to process large amount of data.

  • It has huge storage capacity.

  • It has huge memory power that helps in running heavy data programs.

  • It has high capacity graphic card that helps in displaying graphics, animation, video, etc.

  • The sound system makes it easy to listen to audio.

  • With all these features (discussed above), a computer system is known as high end multimedia computer system.

  • However, all the features listed above are not essentially required for every multimedia computer system, but rather the features of a multimedia computer system are configured as per the need of respective user.

Multimedia Components

Following are the major components of a multimedia computer system −

Text

It contains alphanumeric and some other special characters. Keyboard is usually used for input of text; however, there are some internal (inbuilt) features to include such text.

Graphics

It is technology to generate, represent, process, manipulate, and display pictures. It is one of the most important components of multimedia application. The development of graphics is supported by a different software.

Animation

Computer animation is a modern technology, which helps in creating, developing, sequencing, and displaying a set of images (technically known as ‘frames’). Animation gives visual effects or motion very similar to that of a video file (see image given below).

Animation
Animation

Audio

This technology records, synthesizes, and plays audio (sound). There are many learning courses and different instructions that can be delivered through this medium appropriately.

Video

This technology records, synthesizes, and displays images (known as frames) in such sequences (at a fixed speed) that makes the creation appear as moving; this is how we see a completely developed video. In order to watch a video without any interruption, video device must display 25 to 30 frames/second.

Multimedia Application

Let us now see the different fields where multimedia is applied. The fields are described in brief below −

Presentation

With the help of multimedia, presentation can be made effective.

E-books

Today, books are digitized and easily available on the Internet.

Digital Library

The need to be physically present at a library is no more necessary. Libraries can be accessed from the Internet also. Digitization has helped libraries to come to this level of development.

E-learning

Today, most of the institutions (public as well as private both) are using such technology to education people.

Movie making

Most of the special effects that we see in any movie, is only because of multimedia technology.

Video games

Video games are one of the most interesting creations of multimedia technology. Video games fascinate not only the children but adults too.

Animated films

Along with video games, animated film is another great source of entertainment for children.

Multimedia conferencing

People can arrange personal as well as business meetings online with the help of multimedia conferencing technology.

E-shopping

Multimedia technology has created a virtual arena for the e-commerce.

Computer Security Tips

Advancement of computer technology has radically changed the world; resultantly, most of the works whether it is matter of nation’s security system or buying a shoe online everything depends on computer.

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Such increased dependency also raises the issue of security, as most of the data is now stored in the computer system.

Computer Security
Computer Security

Your computer systems store various sorts of data and hence if it is not secured, then you might be in for a big trouble.

Why Do We Computer Security?

Let us now see why do we need Computer security. It is required for the following major reasons −

  • To prevent damage of the hardware.

  • To prevent theft or damage of the installed software.

  • To prevent theft or damage of stored data and information.

  • To prevent the disruption of service.

  • Likewise, security system keeps the computer system safe by protecting the installed software and the stored data (information).

Protection of Data and Information

Following are the important steps to protect data −

  • Make backup of all your important files.
  • Keep your system virus by using anti-virus software.
  • Keep updating your computer system.
  • Run disk defragmenter and disk cleanup on certain interval of time.
  • Use a firewall.
  • Use anti-spyware software.

Further, if you use internet, then you need to take greater precaution. Consider the following points to understand the precautions that need to be taken −

  • Do not click on any link that you don’t know (as it may be dangerous for your computer – virus attack).

  • Do not open unauthorized an unlawful website (it may damage your computer system).

  • Do not download unsolicited data from unknown website.

What is Defragmentation?

Frequent saving and deleting of file (data) from the hard disk creates problems in performance and also reduce the space; therefore, defragmentation again clean-up the drive and restore the system to run smoothly.

Following are the simple steps of defragmentation 

Defragmentation
Defragmentation

Disk Cleanup

While browsing websites (on internet), many of the files get stored in the hard disk automatically (actually these stored files later help to reopen the website faster); besides some other cookies also get stored in the hard disk. All these stored files create problem along with eating space.

So, disk cleanup process cleans all these files and releases the space occupied by these unwanted files.

Following are the simple steps of disk cleanup 

Disk Cleanup
Disk Cleanup

What is Threat? Types of Threat

Threat in a computer system is a possible danger that might put your data security on stake. The damage is at times irreparable.

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Computer Threat
Computer Threat

Definition

As defined by the National Information Assurance Glossary −

  • “Any circumstance or event with the potential to adversely impact an IS through unauthorized access, destruction, disclosure, modification of data, and/or denial of service.”

  • A computer threat can be “intentional” such as hacking or “accidental” such as malfunctioning of or physical damage.

Types of Threat

Following are the most common types of computer threats −

  • Physical damage − It includes fire, water, pollution, etc.

  • Natural events − It includes climatic, earthquake, volcanic activity, etc.

  • Loss of services − It includes electrical power, air conditioning, telecommunication, etc.

  • Technical failures − It includes problems in equipment, software, capacity saturation, etc.

  • Deliberate type − It includes spying, illegal processing of data, etc.

Some other threats include error in use, abuse of rights, denial of actions, eavesdropping, theft of media, retrieval of discarded materials, etc.

Sources of Threat

The possible sources of a computer threat may be −

  • Internal − It includes employees, partners, contractors (and vendors).

  • External − It includes cyber-criminals (professional hackers), spies, non-professional hackers, activists, malware (virus/worm/etc.), etc.

Common Terms

Following are the common terms frequently used to define computer threat −

Virus Threats

A computer virus is a program designed to disrupt the normal functioning of the computer without the permission of the user.

Spyware Threats

Spyware is a computer program that monitors user’s online activities or installs programs without user’s consent for profit or theft of personal information.

Hackers

Hackers are programmers who put others on threats for their personal gain by breaking into computer systems with the purpose to steal, change or destroy information.

Hackers
Hackers

Phishing Threats

It is an illegal activity through which phishers attempt to steal sensitive financial or personal data by means of fraudulent email or instant messages.

How to Secure Your Computer System from Threats?

Following are the significant tips through which you can protect your system from different types of threat −

  • Install, use, and keep updated Anti-Virus in your system.
  • Install, use, and keep updated a Firewall Program.
  • Always take backups of your important Files and Folders.
  • Use Strong and Typical Passwords.
  • Take precaution especially when Downloading and Installing Programs.
  • Install, use, and keep updated a File Encryption Program.
  • Take precaution especially when Reading Email with Attachments.
  • Keep your Children aware of Internet threats and safe browsing.

What is Computer Virus?

A virus is a computer code or program, which is capable of affecting your computer data badly by corrupting or destroying them.

Computer virus has the tendency to make its duplicate copies at a swift pace, and also spread it across every folder and damage the data of your computer system.

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A computer virus is actually a malicious software program or “malware” that, when infecting your system, replicates itself by modifying other computer programs and inserting its own code.

What is Computer Virus?
What is Computer Virus?

Infected computer programs may include data files, or even the “boot” sector of the hard drive.

Types of Virus

Following are the major types of computer virus 

Worms

This is a computer program that replicates itself at a swift pace. Unlike a computer virus, it is self-contained and hence does not need to be part of another program to propagate itself.

Trojan Horse

A Trojan Horse is also a sort of destructive program that remains disguised in a normal software program. It is not exactly a virus, as it cannot replicate itself. However, there is possibility that virus program may remain concealed in the Trojan Horse.

Bombs

It is similar to Trojan Horse, but Logic bombs have some specialty; these include a timing device and hence it will go off only at a particular date and time.

How Does Virus Affect?

Let us discuss in what ways a virus can affect your computer system. The ways are mentioned below −

  • By downloading files from the Internet.
  • During the removable of media or drives.
  • Through pen drive.
  • Through e-mail attachments.
  • Through unpatched software & services.
  • Through unprotected or poor administrator passwords.

Impact of Virus

Let us now see the impact of virus on your computer system −

  • Disrupts the normal functionality of respective computer system.
  • Disrupts system network use.
  • Modifies configuration setting of the system.
  • Destructs data.
  • Disrupts computer network resources.
  • Destructs of confidential data.

Virus Detection

The most fundamental method of detection of virus is to check the functionality of your computer system; a virus affected computer does not take command properly.

However, if there is antivirus software in your computer system, then it can easily check programs and files on a system for virus signatures.

Virus Preventive Measures

Let us now see the different virus preventive measures. A computer system can be protected from virus through the following −

  • Installation of an effective antivirus software.
  • Patching up the operating system.
  • Patching up the client software.
  • Putting highly secured Passwords.
  • Use of Firewalls.

Most Effective Antivirus

Following are the most popular and effective antivirus from which you can choose one for your personal computer −

  • McAfee Antivirus Plus
  • Symantec Norton Antivirus
  • Avast Pro Antivirus
  • Bitdefender Antivirus Plus
  • Kaspersky Anti-Virus
  • Avira Antivirus
  • Webroot Secure Anywhere Antivirus
  • Emsisoft Anti-Malware
  • Quick Heal Antivirus
  • ESET NOD32 Antivirus

Windows11 – Keyboard Shortcuts and System Commands

Windows11 - Keyboard Shortcuts and System Commands
Windows11 – Keyboard Shortcuts and System Commands

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Microsoft Word

  • F1 key: Get help on a selected command or use the Office assistant.
  • Shift and F1 Key: Review text formatting.
  • F2 Key: Move text or image.
  • Shift + F2 Key: Copy text.
  • F3 Key: Insert an autotext entry.
  • Shift + F3 Key: Change the case of the selected text.
  • F4 Key: Perform last action again.
  • Shift + F4 Key: Perform a Find or Go To action again.
  • F5 Key: Displays the Go To dialogue box. You can also get to Find and Replace from here.
  • Shift + F5 Key: Move to a previous revision.
  • F6 Key: Go to the next frame or pane.
  • Shift + F6 Key: Go to the previous frame or pane.
  • F7 Key: Launch the Spell Checker.
  • Shift + F7 Key: Launch the Thesaurus.
  • F8 Key: Extend the current selection.
  • Shift + F8 Key: Shrink the current selection.
  • F9 Key: Refresh.
  • Shift + F9 Key: Switch between a field code and its result.
  • F10 Key: Show KeyTips.
  • Shift + F10 Key: Display a Shortcut Menu (same as right-clicking).
  • F11 Key: Go to the next field.
  • SHIFT + F11 Key: Go to the previous field.
  • F12 Key: Open Save As, equivalent to tools menu.
  • Shift + F12 Key: Save document, equivalent to tools menu.
  • Ctrl and A: Selects all in the current document.
  • Ctrl and B: Bold text.
  • Ctrl and C: Copies the item or text.
  • Ctrl and D: Displays the Font dialogue box.
  • Ctrl and E: Switch a paragraph between center and left alignment.
  • Ctrl and F: Displays the Find dialog box to search the current document.
  • Ctrl and G: Displays the Go To dialog box to search for a specific location in the current document.
  • Ctrl and H: Displays the Replace dialogue box.
  • Ctrl and I: Italicize text.
  • Ctrl and J: Switch a paragraph between justified and left alignment.
  • Ctrl and K: Create a hyperlink.
  • Ctrl and L: Left align a paragraph.
  • Ctrl and M: Indent a paragraph from the left.
  • Ctrl and N: Create a new document.
  • Ctrl and O: Opens a new document.
  • Ctrl and P: Prints a document.
  • Ctrl and R: Switch the alignment of a paragraph between left and right.
  • Ctrl and S: Saves a document.
  • Ctrl and U: Underlines text.
  • Ctrl and V: Pastes the copied item or text.
  • Ctrl and X: Cuts the selected item or text.
  • Ctrl and Y: Redo the last action.
  • Ctrl and Z: Undo the last action.
  • Ctrl and Enter: Insert a page break.
  • Ctrl and F2: Select Print Preview command.
  • Ctrl and F4: Closes the active window.
  • Ctrl and F6: Opens the next window if multiple are open.

 

Windows Shortcut Keys

  • Windows Key + R: Opens the Run menu.
  • Windows Key + E: Opens Explorer.
  • Alt + Tab: Switch between open programs.
  • Windows Key + Up Arrow: Maximize current window.
  • Ctrl + Shift + Esc: Open Task Manager.
  • Windows Key + Break: Opens system properties.
  • Windows Key + F: Opens search for files and folders.
  • Windows Key + D: Hide/display the desktop.
  • Alt + Esc: Switch between programs in order they were opened.
  • Alt + Letter: Select menu item by underlined letter.
  • Ctrl + Esc: Open Start menu.
  • Ctrl + F4: Close active document (does not work with some applications).
  • Alt + F4: Quit active application or close current window.
  • Alt + Spacebar: Open menu for active program.
  • Ctrl + Left or Right Arrow: Move cursor forward or back one word.
  • Ctrl + Up or Down Arrow: Move cursor forward or back one paragraph.
  • F1: Open Help menu for active application.
  • Windows Key + M: Minimize all windows.
  • Shift + Windows Key + M: Restore windows that were minimized with previous keystroke.
  • Windows + F1: Open Windows Help and Support.
  • Windows + Tab: Open Task view.
  • Windows + Break: Open the System Properties dialog box.
  • Hold Right SHIFT key for eight seconds: Switch FilterKeys on and off.
  • Left Alt + Left Shift + Print Screen: Switch High Contrast on and off.
  • Left Alt + Left Shift + Num Lock: Switch Mouse keys on and off.
  • Press Shift five times: Switch Sticky keys on and off.
  • Hold Num Lock for five seconds: Switch Toggle keys on and off.

 

Internet Explorer Shortcut Keys

  • Alt + Left Arrow/Backspace: Go back to the previous page.

  • Alt + Right Arrow: Go to next page.

  • F5: Refresh page.

  • F11: Toggle between full-screen and regular view.

  • Esc: Stop downloading a page.

  • Ctrl + ( + or -): Zoom in or out of page by 10%.

  • Ctrl + Enter: Adds www. at the beginning and .com to the end of any text entered in the Address bar.

  • Ctrl + D: Add the current site to your favorites.

  • Ctrl + I: View your favorites.

  • Ctrl + N: Open a new window.

  • Ctrl + P: Print the current page.

  • Ctrl + T: Open a new tab.

  • Ctrl + F4: Closes tabs in the background.

  • Ctrl + Tab: Switch between tabs.

  • Spacebar: Click the notification bar.

  • Shift + Spacebar: Move up one page.

  • Alt + Down Arrow: Move a selected item down the favorites list.

 

File Explorer Shortcuts

  • End: Display bottom of current window.
  • Home: Display top of current window.
  • Left Arrow: Collapse the current selections or select a parent folder.
  • Right Arrow: Display the current selection or select the first subfolder.

Windows System Commands

Type the following commands in your Run dialogue box (Windows Key + R) to run specific programs.

  • devmgmt.msc: Device Manager

  • msinfo32: System Information

  • cleanmgr: Disk Cleanup

  • ntbackup: Backup or restore Wizard (Windows Backup Utility)

  • mmc: Microsoft Management Console

  • excel: Microsoft Excel (if installed)

  • msaccess: Microsoft Access (if installed)

  • powerpnt: Microsoft PowerPoint (if installed)

  • winword: Microsoft Word (if installed)

  • frontpg: Microsoft FrontPage (if installed)

  • notepad: Notepad

  • wordpad: WordPad

  • calc: Calculator

  • msmsgs: Windows Messenger

  • mspaint: Microsoft Paint

  • wmplayer: Windows Media Player

  • rstrui: System restore

  • control: Opens the Control Panel

  • control printers: Opens the printers dialogue box

  • cmd: Command Prompt

  • iexplore: Internet Explorer

  • compmgmt.msc: Computer Management

  • dhcpmgmt.msc: DHCP Management

  • dnsmgmt.msc: DNS Management

  • services.msc: Services

  • eventvwr: Event Viewer

  • dsa.msc: Active Directory Users and Computers

  • dssite.msc: Active Directory Sites and Services

Firefox Keyboard Shortcuts

Command Mac OS Windows
Go back a page. Command + Left Arrow Alt + Left Arrow
Go forward a page. Command + Right Arrow Alt + Right Arrow
Reload current page. F5 F5
Toggle between full screen and regular screen. Command + Shift + F F11
Stop page from loading. Esc Esc
Complete a .com address. Command + Return Ctrl + Enter
Complete a .net address. Shift + Return Shift + Enter
Complete a .org address. Command + Shift + Return Ctrl + Shift + Enter
Clear recent history. Command + Shift + Delete Ctrl + Shift + Delete
Add a bookmark for the current page. Command + D Ctrl + D
Display available bookmarks. Command + Shift + B Ctrl + Shift + B
Display the download window. Command + J Ctrl + J
Open a new browser window. Command + N Ctrl + N
Print current page. Command + P Ctrl + P
Opens a new tab. Command + T Ctrl + T
Close the tab. Command + W Ctrl + W
Close window. Command + Shift + W Ctrl + Shift + W
Undo the close of a window. Command + Shift + N Ctrl + Shift + N
Undo the close of a tab. Command + Shift + T Ctrl + Shift + T
Moves through each of the open tabs. Ctrl + Tab Ctrl + Tab
Go to bottom of page. Command + Down Arrow End
Go to top of page. Command + Up Arrow Home

 

 

Microsoft Excel Shortcut Keys

  • F2: Edit the active cell.
  • F5: Displays the Go To box.
  • F7: Open the Spelling dialogue box to check a selected range.
  • F11: Create a chart of data in the current range in a separate sheet.
  • Alt + Shift + F1: Insert a new worksheet.
  • Shift + F3: Opens Insert Function dialogue box.
  • Shift + F5: Opens the Find and Replace dialogue box.
  • Ctrl + Shift + Colon (:): Enter the current time.
  • Ctrl + Semicolon (;): Enter the current date.
  • Ctrl + A: Select all content in the worksheet.
  • Ctrl + B: Bold highlighted selection.
  • Ctrl + I: Italicize highlighted selection.
  • Ctrl + K: Open the Insert hyperlink dialogue box.
  • Ctrl + U: Underline highlighted selection.
  • Ctrl + 5: Apply strikethrough formatting.
  • Ctrl + P: Brings up the print dialog box.
  • Ctrl + Z: Undo.
  • Ctrl + F9: Minimize a workbook window to an icon.
  • Ctrl + F10: Maximize a selected workbook window.
  • Ctrl + F6: Switch to the next workbook window when multiple are open.
  • Ctrl + Page Up: Move to previous sheet in a workbook.
  • Ctrl + Page Down: Move to next sheet in a workbook.
  • Ctrl + Tab: Switch to next tab in dialogue box.
  • Ctrl + Apostrophe (‘): Insert the value of the above cell into the cell currently selected.
  • Ctrl + Shift + !: Apply the Number format.
  • Ctrl + Shift + $: Apply the Currency format.
  • Ctrl + Shift + #: Apply the Date format.
  • Ctrl + Shift + %: Apply the Percentage format.
  • Ctrl + Shift + ^: Apply the Exponential format.
  • Ctrl + Shift + @: Apply the Time format.
  • Ctrl + Arrow Key: Move to the edge of the current data region in a worksheet.
  • Ctrl + Space: Select an entire column in a worksheet.
  • Shift + Space: Select an entire row in a worksheet.

 

Shortcuts for Mac

  • Command + X: Cut selected text and copy it.
  • Command + C: Copy selected text.
  • Command + V: Paste copied text.
  • Command + Z: Undo previous command.
  • Command + A: Select all items.
  • Command + F: Open Find window to search text.
  • Command + H: Hide windows of the front app.
  • Command + N: Open a new document or window.
  • Command + O: Open a selected item.
  • Command + P: Print current document.
  • Command + S: Save current document.
  • Command + W: Close front window.
  • Command + Q: Quit the app.
  • Command + M: Minimize the front window to the Dock.
  • Command + Spacebar: Open Spotlight search field.
  • Command + Tab: Switch between open apps.
  • Command + B: Bold selected text.
  • Command + I: Italicize selected text.
  • Command + U: Underline selected text.
  • Command + Semicolon (;): Find misspelled words in document.
  • Option + Command + Esc: Choose an app to force quit.
  • Shift + Command + Tilde (~): Switch between open windows.
  • Shift + Command + 3: Take a screenshot.
  • Fn + Up Arrow: Scroll up one page.
  • Fn + Down Arrow: Scroll down one page.
  • Fn + Left Arrow: Scroll to beginning of document.
  • Fn + Right Arrow: Scroll to end of document.

 

Chrome Keyboard Shortcuts

Command MacOS Windows
Open new window. Command + N Ctrl + N
Open new tab. Command + T Ctrl + T
Reopen the last closed tab. Command + Shift + T Ctrl + Shift + T
Move to next tab. Command + Option + Right Arrow Ctrl + Tab
Move to previous tab. Command + Option + Left Arrow Ctrl + Shift + Tab
Open previous page in browsing history. Command + [ Alt + Left Arrow
Open next page in browsing history. Command + ] Alt + Right Arrow
Close current tab. Command + W Ctrl + W
Close current window. Command + Shift + W Alt + F4
Open Bookmarks Manager. Command + Option + B Ctrl + Shift + O
Open History page. Command + Y Ctrl + H
Open Downloads page. Command + Shift + J Ctrl + J
Open Find Bar. Command + F Ctrl + F
Print current page. Command + P Ctrl + P
Save current page. Command + S Ctrl + S
Reload current page. Command + R F5
Save current page as a bookmark. Command + D Ctrl + D
Toggle full-screen mode. Command + Ctrl + F F11

 

 

Wireless Communication – Satellit

A satellite is an object that revolves around another object. For example, earth is a satellite of The Sun, and moon is a satellite of earth.

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A communication satellite is a microwave repeater station in a space that is used for telecommunication, radio and television signals. A communication satellite processes the data coming from one earth station and it converts the data into another form and send it to the second earth station.

How a Satellite Works

Two stations on earth want to communicate through radio broadcast but are too far away to use conventional means. The two stations can use a relay station for their communication. One earth station transmits the signal to the satellite.

Uplink frequency is the frequency at which ground station is communicating with satellite. The satellite transponder converts the signal and sends it down to the second earth station, and this is called Downlink frequency. The second earth station also communicates with the first one in the same way.

Advantages of Satellite

The advantages of Satellite Communications are as follows −

  • The Coverage area is very high than that of terrestrial systems.
  • The transmission cost is independent of the coverage area.
  • Higher bandwidths are possible.

Disadvantages of Satellite

The disadvantages of Satellite Communications are as follows −

  • Launching satellites into orbits is a costly process.
  • The bandwidths are gradually used up.
  • High propagation delay for satellite systems than the conventional terrestrial systems.

Satellite Communication Basics

The process of satellite communication begins at an earth station. Here an installation is designed to transmit and receive signals from a satellite in orbit around the earth. Earth stations send information to satellites in the form of high powered, high frequency (GHz range) signals.

The satellites receive and retransmit the signals back to earth where they are received by other earth stations in the coverage area of the satellite. Satellite’s footprint is the area which receives a signal of useful strength from the satellite.

The transmission system from the earth station to the satellite through a channel is called the uplink. The system from the satellite to the earth station through the channel is called the downlink.

Satellite Frequency Bands

The satellite frequency bands which are commonly used for communication are the Cband, Ku-band, and Ka-band. C-band and Ku-band are the commonly used frequency spectrums by today’s satellites.

It is important to note that there is an inverse relationship between frequency and wavelength i.e. when frequency increases, wavelength decreases this helps to understand the relationship between antenna diameter and transmission frequency. Larger antennas (satellite dishes) are necessary to gather the signal with increasing wavelength.

Earth Orbits

A satellite when launched into space, needs to be placed in certain orbit to provide a particular way for its revolution, so as to maintain accessibility and serve its purpose whether scientific, military or commercial. Such orbits which are assigned to satellites, with respect to earth are called as Earth Orbits. The satellites in these orbits are Earth Orbit Satellites.

The important kinds of Earth Orbits are −

  • Geo-synchronous Earth Orbit
  • Geo-stationary Earth Orbit
  • Medium Earth Orbit
  • Low Earth Orbit

Geo-synchronous Earth Orbit (GEO) Satellites

A Geo-synchronous Earth orbit Satellite is one which is placed at an altitude of 22,300 miles above the Earth. This orbit is synchronized with a side real day(i.e., 23hours 56minutes). This orbit can have inclination and eccentricity. It may not be circular. This orbit can be tilted at the poles of the earth. But it appears stationary when observed from the Earth.

The same geo-synchronous orbit, if it is circular and in the plane of equator, it is called as geo-stationary orbit. These Satellites are placed at 35,900kms (same as geosynchronous) above the Earth’s Equator and they keep on rotating with respect to earth’s direction (west to east). These satellites are considered stationary with respect to earth and hence the name implies.

Geo-Stationary Earth Orbit Satellites are used for weather forecasting, satellite TV, satellite radio and other types of global communications.

GEO
GEO

The above figure shows the difference between Geo-synchronous and Geo- Stationary orbits. The Axis of rotation indicates the movement of Earth.

The main point to note here is that every Geo-Stationary orbit is a Geo-Synchronous orbit. But every Geo-Synchronous orbit is NOT a Geo-stationary orbit.

Medium Earth Orbit (MEO) Satellites

Medium earth orbit (MEO) satellite networks will orbit at distances of about 8000 miles from earth’s surface. Signals transmitted from a MEO satellite travel a shorter distance. This translates to improved signal strength at the receiving end. This shows that smaller, more lightweight receiving terminals can be used at the receiving end.

Since the signal is travelling a shorter distance to and from the satellite, there is less transmission delay. Transmission delay can be defined as the time it takes for a signal to travel up to a satellite and back down to a receiving station.

For real-time communications, the shorter the transmission delay, the better will be the communication system. As an example, if a GEO satellite requires 0.25 seconds for a round trip, then MEO satellite requires less than 0.1 seconds to complete the same trip. MEOs operates in the frequency range of 2 GHz and above.

Low Earth Orbit (LEO) Satellites

The LEO satellites are mainly classified into three categories namely, little LEOs, big LEOs, and Mega-LEOs. LEOs will orbit at a distance of 500 to 1000 miles above the earth’s surface.

This relatively short distance reduces transmission delay to only 0.05 seconds. This further reduces the need for sensitive and bulky receiving equipment. Little LEOs will operate in the 800 MHz (0.8 GHz) range. Big LEOs will operate in the 2 GHz or above range, and Mega-LEOs operates in the 20-30 GHz range.

The higher frequencies associated with Mega-LEOs translates into more information carrying capacity and yields to the capability of real-time, low delay video transmission scheme.

High Altitude Long Endurance (HALE) Platforms

Experimental HALE platforms are basically highly efficient and lightweight airplanes carrying communications equipment. This will act as very low earth orbit geosynchronous satellites.

These crafts will be powered by a combination of battery and solar power or high efficiency turbine engines. HALE platforms will offer transmission delays of less than 0.001 seconds at an altitude of only 70,000 feet, and even better signal strength for very lightweight hand-held receiving devices.

Orbital Slots

Here there may arise a question that with more than 200 satellites up there in geosynchronous orbit, how do we keep them from running into each other or from attempting to use the same location in space? To answer this problem, international regulatory bodies like the International Telecommunications Union (ITU) and national government organizations like the Federal Communications Commission (FCC) designate the locations on the geosynchronous orbit where the communications satellites can be located.

These locations are specified in degrees of longitude and are called as orbital slots. The FCC and ITU have progressively reduced the required spacing down to only 2 degrees for C-band and Ku-band satellites due to the huge demand for orbital slots.

Explore Window in M S Excel

The following basic window appears when you start the excel application. Let us now understand the various important parts of this window.

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Explore Excel Window
Explore Excel Window

File Tab

The File tab replaces the Office button from Excel 2007. You can click it to check the Backstage view, where you come when you need to open or save files, create new sheets, print a sheet, and do other file-related operations.

Quick Access Toolbar

You will find this toolbar just above the File tab and its purpose is to provide a convenient resting place for the Excel’s most frequently used commands. You can customize this toolbar based on your comfort.

Ribbon

Excel Ribbon
Excel Ribbon

Ribbon contains commands organized in three components −

  • Tabs − They appear across the top of the Ribbon and contain groups of related commands. Home, Insert, Page Layout are the examples of ribbon tabs.

  • Groups − They organize related commands; each group name appears below the group on the Ribbon. For example, group of commands related to fonts or group of commands related to alignment etc.

  • Commands − Commands appear within each group as mentioned above.

Title Bar

This lies in the middle and at the top of the window. Title bar shows the program and the sheet titles.

Help

The Help Icon can be used to get excel related help anytime you like. This provides nice tutorial on various subjects related to excel.

Zoom Control

Zoom control lets you zoom in for a closer look at your text. The zoom control consists of a slider that you can slide left or right to zoom in or out. The + buttons can be clicked to increase or decrease the zoom factor.

View Buttons

The group of three buttons located to the left of the Zoom control, near the bottom of the screen, lets you switch among excel’s various sheet views.

  • Normal Layout view − This displays the page in normal view.

  • Page Layout view − This displays pages exactly as they will appear when printed. This gives a full screen look of the document.

  • Page Break view − This shows a preview of where pages will break when printed.

Sheet Area

The area where you enter data. The flashing vertical bar is called the insertion point and it represents the location where text will appear when you type.

Row Bar

Rows are numbered from 1 onwards and keeps on increasing as you keep entering data. Maximum limit is 1,048,576 rows.

Column Bar

Columns are numbered from A onwards and keeps on increasing as you keep entering data. After Z, it will start the series of AA, AB and so on. Maximum limit is 16,384 columns.

Status Bar

This displays the sheet information as well as the insertion point location. From left to right, this bar can contain the total number of pages and words in the document, language etc.

You can configure the status bar by right-clicking anywhere on it and by selecting or deselecting options from the provided list.

Dialog Box Launcher

This appears as a very small arrow in the lower-right corner of many groups on the Ribbon. Clicking this button opens a dialog box or task pane that provides more options about the group.

Backstage View in M S Excel

The Backstage view has been introduced in Excel 2010 and acts as the central place for managing your sheets. The backstage view helps in creating new sheets, saving and opening sheets, printing and sharing sheets, and so on.

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Getting to the Backstage View is easy. Just click the File tab located in the upper-left corner of the Excel Ribbon. If you already do not have any opened sheet then you will see a window listing down all the recently opened sheets as follows −

Excel Backstage View
Excel Backstage View

If you already have an opened sheet then it will display a window showing the details about the opened sheet as shown below. Backstage view shows three columns when you select most of the available options in the first column.

Excel Backstage View 2
Excel Backstage View 2

First column of the backstage view will have the following options 

S.No. Option & Description
1

Save

If an existing sheet is opened, it would be saved as is, otherwise it will display a dialogue box asking for the sheet name.
2

Save As

A dialogue box will be displayed asking for sheet name and sheet type. By default, it will save in sheet 2010 format with extension .xlsx.
3

Open

This option is used to open an existing excel sheet.
4

Close

This option is used to close an opened sheet.
5

Info

This option displays the information about the opened sheet.
6

Recent

This option lists down all the recently opened sheets.
7

New

This option is used to open a new sheet.
8

Print

This option is used to print an opened sheet.
9

Save & Send

This option saves an opened sheet and displays options to send the sheet using email etc.
10

Help

You can use this option to get the required help about excel 2010.
11

Options

Use this option to set various option related to excel 2010.
12

Exit

Use this option to close the sheet and exit.

Sheet Information

When you click Info option available in the first column, it displays the following information in the second column of the backstage view −

  • Compatibility Mode − If the sheet is not a native excel 2007/2010 sheet, a Convert button appears here, enabling you to easily update its format. Otherwise, this category does not appear.

  • Permissions − You can use this option to protect the excel sheet. You can set a password so that nobody can open your sheet, or you can lock the sheet so that nobody can edit your sheet.

  • Prepare for Sharing − This section highlights important information you should know about your sheet before you send it to others, such as a record of the edits you made as you developed the sheet.

  • Versions − If the sheet has been saved several times, you may be able to access previous versions of it from this section.

Sheet Properties

When you click Info option available in the first column, it displays various properties in the third column of the backstage view. These properties include sheet size, title, tags, categories etc.

You can also edit various properties. Just try to click on the property value and if property is editable, then it will display a text box where you can add your text like title, tags, comments, Author.

Exit Backstage View

It is simple to exit from the Backstage View. Either click on the File tab or press the Esc button on the keyboard to go back to excel working mode.

Entering Values in M S Excel

Entering values in excel sheet is a child’s play and this chapter shows how to enter values in an excel sheet. A new sheet is displayed by default when you open an excel sheet as shown in the below screen shot.

Enter Text
Enter Text

Sheet area is the place where you type your text. The flashing vertical bar is called the insertion point and it represents the location where text will appear when you type. When you click on a box then the box is highlighted. When you double click the box, the flashing vertical bar appears and you can start entering your data.

So, just keep your mouse cursor at the text insertion point and start typing whatever text you would like to type. We have typed only two words “Hello Excel” as shown below. The text appears to the left of the insertion point as you type.

Hello Excel
Hello Excel

There are following three important points, which would help you while typing −

  • Press Tab to go to next column.
  • Press Enter to go to next row.
  • Press Alt + Enter to enter a new line in the same column.