Wireless Networks cont'd

Previous: Wireless LANs

3)Wireless WANs
The radio n/w used for cellular telephones is an example of a low bandwidth wireless system.This system has gone through 3 generations-
1)First generation-analog & voice only
2)Second generation-digital & for voice only
3)Third generation-digital & is for both voice & data

Wireless LANs can operate at 50 Mbps.
Cellular system operate at about 1 Mbps.
Wireless internet service is often called local multipoint distribution service eg.mts
Almost all wireless n/ws hook up to the wired n/w at some point to provide access to files,databases & the internet.
Many n/ws exist in the world,often with different h/w & s/w.
The fulfillment of this desire requires that different & frequently incompatible n/ws be connected by means of machines called gateways to make the connection and provide the necessary translation, both in terms of h/w and s/w called internetwork or internet.
If the system within the gray area contains only routers it is a subnet.
If it contains both routers & hosts it is a WAN.
As an analogy,the telephone system consists of telephone switching offices connected to one another by high speed lines & to houses & business by low speed lines.
These lines and equipment,owned and managed by telephone company form the subnet of telephone system.

Next:Network Connecting Devices

Wireless LANs

Previous: Wireless Networks

2)In Wireless LANs,if the systems are close enough, they can communicate directly with one another in a peer to peer configuration. Wireless LANs are common in small offices and homes.There is a standard for wireless LANs called IEEE 802.11
Wireless LANs are systems in which every computer has a radio modem and antenna with which it can communicate with other system.

Next

Wireless Networks

Previous

Wireless n/w can be divided into 3 main categories-

1)System interconnection
2)Wireless LANs
3)Wireless WANs

System interconnection
It is all about interconnecting the components of a computer using short-range radio.
Some companies got together to design a short-range wireless n/w called Bluetooth to connect these components without wires.
Bluetooth also allows digital cameras,headsets,scanners and other devices to connect to a computer by merely being brought within range.
System interconnection n/w use the master slave paradigm. The system unit is normally the master,talking to the mouse,keyboard as slaves.
The master tells the slaves what addresses to use,when they can broadcast ,how long they can transmit, what frequencies they can use etc.


Next: Wireless LANs

Wide Area Network cont'd

Previous:WAN

The collection of communication lines and routers form the subnet.When a packet is sent from 1 router to another via 1 or more intermediate routers,the packet is received at each intermediate router in its entirety, stored until required output line is free and then forwarded.A subnet organized according to this principal is called a store and forward packet switched subnet.
When packet are small and all the same size,they are often called cells.
Packet travelling bearing number in the sequence.
Not all WANs are packet switched. A second possibility for a WAN is a satellite system.
Each router has an antenna through which it can send and receive.All routers can hear the output from satellites.


Next: Wireless Network

Wide Area Network or WAN

WAN spans a large geographical area,often a country or continent. The job of the subnet is to carry messages from host to host,just as telephone system carries words from speaker to listener.
    In most wide area n/ws,the subnet consists of 2 distinct components : transmission lines & switching elements.
Transmission lines move bits between machines. They can be made of copper wire,optical fiber or even radio links.
When data arrive on an incoming line,the switching element must choose an outgoing line on which to forward them.
Switching element is also called router.


Next:WAN contn'd 

Computer Ergonomics

Unfortunately prolonged postures, coupled with high levels of concentration & the occasional frustration of things going less than perfectly can lead to physical problems. A little knowledge of principles of ergonomics, how people interact safely & efficiently with machines & their work environment can save a lot of discomfort & maximize both productivity & enjoyment.

Machine setup

Visibility
You must be able to see what you are doing easily to avoid eye strain & neck pain.Have adequate light.

Chairs
Experiment with chair height and tilt until you get it the way your body likes.

Keyboard
Be sure to get the height right to prevent too much bend at the wrist & have some support. The arms should hang loose to prevent the shoulder muscles from cramping.

Mouse
The continual clicking & small,precise motions involved in mouse use are a repetitive action that can be a health hazard.A few basic rules can help-
1)Hold mouse loosely. Use a light touch when you click.
2)Use your whole arm & shoulder to move the mouse not just your wrist.
3)Keep wrist relaxed & neutral not bent.
4)Avoid prolonged postures.Rotate your shoulders,gently shake your hands & fingers.



Human Set Up

Posture
Footrests help as cushions if your chair is not providing adequate support.

Eyes
Look away from the screen occasionally. Blinking moistens the eyes to prevent burning from dryness.

Warm Up
Do neck stretches,wrist wiggles & leg stretches before login

Breaks
At least once an hour,get right up off your seat & walk around, stretch,yawn,get the blood flowing & stimulate the joints.

Keep an eye distance of 25 inch from computer to avoid eye problems!

Holidays have started & children are spending much of their time on mobile & computers.WHO has reported that children are spending much of their time on indoor games rather than

outdoor games.According to report,more than 15% of children are spending continuous 4 hours on TV due to which they are suffering from eye problems.
Apart from eyes,neck,shoulders, back are also affected & children become fatigued.

Dry eye syndrome
When children play on mobile or computer their eye is in direct contact with light,that's why eye is the most adversely affected.
Dry eye syndrome is caused by the rays coming out of mobile & computer. Tears or moisture coming out if eyes protects the cornea or conjunctiva from drying.We have a layer of moisture in our eyes that gives eyelids glistening. Due to this eyelids can be blinked easily.Water in eyes dries up due to working for long hours on computers & consequently eyes become weak.

Backache
If we don't take a correct posture on computers,it can affect our neck,back & eyes.Continuous typing can bring swelling in wrist of children. Playing games for long hours on mobile can create twisted fingers in children.

Eyes
Dos-

1)After every 1 hour close your eyes for 10 minutes.
2)Keep on blinking your eyes while working on mobile or computer.
3)Add antiglower screen on computer screen.This will reduce harmful rays.
4)Keep a 25 inch distance from computer screen.
5)Keep a distance of 16 inch from mobile screen.
6)Keep back straight while working on computer.
7)The other end of chair should be straight.


Donts-
1)Don't use old specs while working on computer.
2)If computer is old change screen.Rays from screen are harmful to eyes.

Networking continued Page 5 - Mesh Network

Mesh network

Mesh network connect all computers to each other.

Advantages and Disadvantages of Mesh network


Disadvantage-

1)The cable requirements are high.
2)Mesh n/WS are difficult to install because each device must be linked directly to all other devices.

Advantage-

1)Alternative paths allow each computer to balance the load to other computer systems in the n/w.Eg. telephone exchange
2)Mesh topology resist media failure better than other topologies.

Continued on Page 6-WAN

Networking contn'd-Page 2,Metropolitan Area Network (MAN)

A MAN covers a city,eg. Cable TV in cities.
A special standard has adopted for MAN is called DQDB(Distributed Queue Dual Bus).
Recent development in high-speed wireless internet access resulted in another MAN,which has been standardized as IEEE 802.16
A key aspect of a MAN is that there is broadcast medium to which all the computers are attached.
A n/w can be made by following topologies:
1.Star n/w
2.Tree n/w
3.Mesh n/w


Continued on Page 3 - Star Network

Computers-MS Access

MS Access

MS Access is a powerful database management system that functions in the windows environment and allows to create and process data in a database.Some of the key features are:
Data entry and update:Access provides easy mechanisms for adding,changing and deleting data,including the ability to make mass changes in a single operation.
Queries:Using Access,allows to ask complex questions concerning data in the database very easily and receive instant answers.
Forms:Access helps to produce attractive and useful forms for viewing and updating data.
Reports:Access contains a feature to create sophisticated reports easily for presenting data.
Database is a collection of data organized in a manner that allows access,retrieval and use of that data.Access allows to add,change and delete data in the database.
A database consists of a collection of tables in Access.The rows in the tables are called records.A field contains a specific piece of information within the record.
Starting Access
Click on Start button.
Click on All Programs.
Click on MS Office.
Click on MS Access.



Understanding Access Window
Title bar:It shows the name of the displayed database.
File tab:It displays file commands as New and Open.
Quick Access Toolbar:It displays quick access buttons to Save,Undo and Redo commands.
Status bar:displays information about the current object or view.
Create a New Table
By entering data into a table,you can start a database.Tables consist of columns and rows that intersect to form cells for holding data.Each row is considered to be a record in a table.You can use columns to hold fields in a table.
Click on create tab on the ribbon.
Click on table button.
Access opens a new table in datasheet view.
Double-click the column header to create a field name.
Type a name for the field.
Press Enter key from keyboard.
Click on next column.
Select the data type for the field.Eg. select Text,if you want to add Name field.
If you want to change the data type,click on the arrow button andame column.
change the data type according to your need.
After selecting the data type,its properties will be displayed in the lower pane.
After selecting the data type,press the TAB key to move the insertion point to the description column.
Press TAB key again to move to the Field Name column in the second row.
Type the text in field name column.
Press the TAB key to move to the Data Type column.
The word ‘Text’ is currently displayed in that field.
Press the TAB key to move the insertion point to Description column,if you want the data type as text.
Type the text for the description column.
Repeat steps to make the remaining entries in the table to complete it.

Setting a Primary Key
A primary key is a key that differentiates the records in a file.The data stored in a key field contains data that is unique to a specific record.A student record,example,would use Roll number as a key field because it uniquely identifies each student.
In each new table that you create,you’ll want to set one field as the primary key.Access uses this key to relate this table’s records to those in another table.
Choose the field that you want to set as the primary key.
Click on the primary key button.
The field will be set as the primary key,indicating by a small key in the field of selector column.To remove it,select the primary key field and click on the primary key button again.
Save a Table
After creating a new table,it must be saved to make it a permanent part of the database.
Right click on the table’s tab.
Click on Save.
Type a name for the table.
Click on OK.
The table remains open,and its new name appears on its tab.
Insert and Delete fields
New fields can be inserted and existing removed into a field list.A new row appears in the grid-above the one selected.
Steps-
Select the field where you want new field should appear above.
Click on design tab.
Click on insert rows.
A new row appears above the selected row.
Type a field name and choose a field type.

Select a field you want to delete.
Click on design tab.
Click on delete rows.
The row will be deleted,along with any data that the fields have.

Understanding Data Type
Each field has a data type that defines what you can store in it.Data entry is restricted to valid entries for the type you choose,which helps to prevent data entry errors.Example,you cannot enter letters in a field set to Number,and you must enter valid dates or times in a date/time field.

Text:This is a general purpose field containing any data.It has a limit of 255 characters and cannot be used for numeric calculation.
Memo:This has a limit of 63,999 characters;used for detailed,descriptive fields.
Number:This type stores numeric data that you can use in calculations.It can also hold symbols,as decimal points and commas.
Date/Time:This type only stores numbers representing valid dates and times.
Currency:Stores currency data that you can use in calculations.
Auto Number:stores a sequencial number for each record.
Yes/No:The value -1 represents Yes,and the value 0 represents No,but the field can be formatted to display values as
True/False or Yes/No.
OLE Object:stores objects created in another application-as Word or Excel-that you can link to or fix in an Access table.
Hyperlink:You can link to websites,email addresses,files on your computer,files on any other location.
Attachment:You can attach data files.

Change Data Type

The data type of a field can be changed anytime to better represent data.Field types should be set before entering data into table,field type can be changed anytime.

Click on the down arrow to ope the Data Type list for the field.
Click on new type.
To save the changes to the table,click on save.
Click on yes to allow the deletion of records that violate the new field type’s rules.
No can be clicked to abandon the change.

Rename a table

A table can be renamed at any time.Access automatically updates all references to the table throughout the database.The table must be closed in order to rename it.

Right click on the table name in the navigation pane.A short cut menu appears.
Choose rename from the shortcut menu.The table name appears in edit mode.
Type the new name for the table and press enter key from the keyboard.
The new name appears on the table.
Click on the table name in the navigation pane.
Click on Home tab.
Click on delete button from record group.
A confirmation dialog box opens.
Click Yes.
The table will delete.

Adding Records to a table

The first step is to create a table by building the structure and saving the table.The second step is to add records to the table.The table must be open so that the records can be added to the table.The table displays in datasheet view.In datasheet view,the table is represented as a collection of rows and columns called a datasheet.

Double click on table in the customer:database window.
Type the customer id in the first customer id field.
Press the tab key to complete the entry for the customerid field.
Type the following entries by pressing the tab key after each one to complete the record.
After typing the last entry,press the tab key.
The insertion point comes to the customerid field in the second row.
Add the remaining records by following the same steps you used to add first record.
Click on save,to save the changes.

Computers-Photoshop

Photoshop

Photoshop is a graphic editor  that allows you to create,modify,combine and optimize digital images.Photoshop creates sophisticated images for both print and web.
You can brighten,darken and change the hue of colors in parts of image with photoshop’s dodge,burn and similar tools.Photoshop’s effects let you easily add drop shadows,3d shading and other styles to images.
After editing,images can be used in a variety of ways.
PHOTOSHOP WORKSPACE
Menu Bar
Displays the menus that contain most of photoshops commands.
Option Bar
Displays controls that let you customize the selected tool in the toolbox.
Toolbox
Displays a variety of icons,each one representing an image editing tool.You click and drag inside your image to apply most of the tools.
Image Window
Contains each image you open in photoshop.
Panels
Small windows that give you access to common commands and resources.You can click the tabs and icons to display and hide panels.
The Photoshop Toolbox
The toolbox contains many separate tools.You can simply click on the tool to select it for working on your image.If you leave your mouse cursor over the tool,photoshop will indicate the name of the tool and the keyboard shortcut to access the tool.A small black arrow in the bottom right corner of the tool indicates additional tools are stacked behind.
Create a new image windows
Photoshop project can be started by creating a blank image.
Click on file.The file menu will open.
Click on new.
Type a name for the image.
Cropping the image
Crop tool can change the size of an image.
Click on crop tool.
Click and drag to select the area of the image you want to keep.
You can click and drag the sides and corner handles to adjust the size of the cropping boundary.
Zoom Tool
With zoom,magnification of an image can be changed.
Selecting with marquee tools
Marquee tools are used to select a rectangular or elliptical area of image.
Selecting Lasso tool
You can create oddly shaped selections with lasso tool.Then you can move,delete,or stylize the selected area using other photoshop commands.
Click on lasso tool.
Click and drag with your cursor to make a selection.
Drag to the beginning point and release the mouse button to complete the selection.

Moving the selection

With the help of move tool,a selection can be moved which helps to rearrange elements of image.

Rubber Stamp Tool

You can clean up small flaws or erase elements in image with the help of rubber stamp tool.The tool copies information from one area of an image to another.

Selecting with Magic Wand Tool

Groups of similarly colored pixels can be selected with the use of Magic Wand tool.

Click on magic wand tool.
Click on the area you want to select inside the image.
Photoshop selects the pixels you clicked and any similarly colored pixels near it.

Using Paintbrush tool

You can use the paintbrush tool to add color to your image.

C lick on the Paintbrush tool.


Click on the rubber stamp in the toolbox.
Click on the down arrow of brush.
Select the brush size and type.
Press the alt key on the keyboard and click the area of the image where you want to copy from.
Click and drag to apply the rubber stamp.
The area is copied to where you click and drag.
Click and drag repeatedly over the area to achieve the desired effect.

Color Modes

You can change the color modes in the picture.

RGB Mode

RGB is the most common mode for working with color images in photoshop.

Click on image in the menu bar.
Click on Mode.
Click on RGB color.
Click on window to view the different color components of an RGB image.
Click on channels.
Click on any channel(Red,Green,Blue).
A grayscale version of the image displays the amount of channels the image contains.

Converting color images to grayscale

To remove the color from your image,you can convert it to grayscale mode.

Click on image in the menu bar.
Click on mode.
Click on grayscale.
Click on Discard.

Foreground and Background colors

A foreground color and a background color can be selected to work in photoshop.

Click on foreground color icon.
Click in the color window to select a color.
Drag the slider or enter the value in the boxes to change the range of color in the window.
Click on OK.


Click on the background Color icon.
The color picker dialog box will open.
Click in the color window to select a color.
Drag the slider to change the range of color in the window.
Click on OK.

Selecting color using Eyedropper Tool

You can select a color from an open image with the eyedropper tool.This tool enables you to paint using a color already present in your image.

Click on the eyedropper tool.
Place the eyedropper tool over an open image and click to select the color under eyedropper tool’s tip.



Brightness and Contrast

You can adjust the brightness and contrast of image.

Click on Image in the menu bar.
Click on adjustments.
Click on Brightness/Contrast.
To lighten the image,click and drag the brightness:slider to the right,or darken the image by dragging it to the left.
To increase the contrast,click and drag the contrast:slider to the right,or to decrease contrast,drag it to the left.
Click on OK.


Color Balance

To change the amount of specific colors in your image,you can use the color balance command.
Click on Image in the menu bar.
Click on adjustments.
Click on color balance.
Select the radio button of tones in the image that you want to affect.
Click and drag the color slider to adjust the color or type a number from -100 to 100 in the color levels:field.
Click on OK.


Using Dodge Effect

You can use the dodge tool to lighten a specific area of an image.Dodge is a photographic term that describes the diffusing of light when developing a film negative.

Click on the dodge tool.
Click on the down arrow button of brush:menu and choose the brush size and type that you would like to use.
You can also select the range of colors you want to affect.
Click and drag over the area that you want to lighten.

Using Burn Effect

You can use the burn tool to darken a specific area of an image.Burn is a photographic term that describes the focusing of light when developing a film negative.

Click and hold the dodge tool.A box appears.
Click the burn tool in the box that appears.
Click on the down arrow button of brush:menu and choose the brush size and type.
You can also select the range of colors you want to affect.
Click and drag over the area that you want to darken.

Computers-Input and Output devices

Input and Output Devices

We know about different parts of a computer.All these parts are either Input or Output Device.
Example:
Step1:Take some mangoes.
Step2:Cut them.
Step3:Put them in the juicer.
Step4:Switch on the juicer for 5-6 minutes.
Step5:Switch on the juicer.
Step6:Pour out the juice.

The mangoes are input.
The juice we get is the output.
Device means machine(Here juicer is the device).
A computer needs information and Data to work.
In the same way all characters,numbers and words given to the computer are called Input.
The result given by the computer is called Output.
Input devices transfer data and information into the computer.
Output devices give the desired results out of the computer.

MS Word-Mail Merge!

CREATE A LETTER FOR MAIL MERGE

Open the Word document that you want to use as the letter.
Click the Mailings tab.
Click on Start Mail Merge.
Click on Letters.
Click on Select Recipients.
The New Address List dialog box appears,displaying areas where information can be entered.
Type the appropriate information for each person.
To enter information for another person,click on New Entry.
On finishing creating mailing list,click OK.
Click on save button to save the file.

Computers-MS Word

MS WORD

The word processor is a software package which helps to enter and edit an entire document much faster than the usual manual way.MS Word is a window based application and is normally available in the program menu or in the desktop as an icon.
The menu bar provides access to the various word commands.The toolbar contains some useful buttons which help us to access some commands very quickly.
The formatting toolbar helps to format the document.The Ruler is used to set the margin of the page and is also used to set tabs.
There are two options to work on a word document.Either you will work on the pre-existing file or you will create a new one.For this,
a)Click on File menu.
b)On the menu list that drops:
click on Open menu,for pre existing file.
Click on new menu,to create new file.
For saving a document,click on File menu and then Save.
Selecting text:
Steps:
Bring cursor to left of the text.
Hold shift key.
Gradually keep on pressing the right arrow key of the keyboard.
Formatting
Now, when the text is selected, we can do various formatting to the text.
Bring mouse pointer on B and then click it. Selected text becomes bold.
To bring it back to normal text, click it again.
To make the text italics, click I next to ‘B’.
To underline text, click U button next to I.

To close all opened documents, click exit in the File menu.

Adding WordArt
Select the text you want to convert into the WordArt.
Click on Insert tab.
Click on WordArt.A list of options appears.
Click on the WordArt style you want to use.
Type text.
Click OK.

Creating a Table
Click in the document where you want to insert a table.
Click on Insert.
Click on Table.
Enter rows and columns.
Word adds table to the document.

Adding Page Number
Click on Insert
Click on Page Number.
Click on location for page numbers.

Change Page Orientation

Click on Page Layout.
Click on Orientation.Orientation may be portrait or landscape.Click an option.

Word changes the orientation.

Inserting a Page Break

If you wish to start a new page at the same specific location in your document,you can insert a page break.

Click in the document where you want to insert a page break.
Click on insert tab.
Cick on page break button.

Remove Page Break

Click on Draft View button from the status bar to display the document in Draft View.
A Page break line appears.
Click on page break line and then press Delete key from the keyboard.

  Changing Alignment of Text

Text can be aligned in different ways to enhance the appearance of document.By default,Word assigns the Left Align command.

Select the text that you want to format.
Click on Home tab.
Click on one of the following buttons:
Align Left to left align text.
Center button to center text.
Align Right to right align text.
Justify button to justify text.

Changing the Line Spacing

Select the text you want to use a different line spacing.
Click on Home tab.
Click on Line spacing to display the available line spacing options.
Click on the line spacing option you want to use.

Changing the Color of Text
Select text that you want to format.
Click on Home tab.
Click on down arrow of font color.
Click on any color.

Changing the size of text
Select the text  you want to change to a different font.
Click on Home tab.
Click on down arrow of font size.
Click on the size you want to use.

Count  words in a Document

When a work requires a specific number of words,you can use word count to count the number of words.

The number of words in the document is the number across from word count.
The number of words in the document appears on the status bar.

Set Line Spacing between paragraphs

The amount of space between paragraphs of text can be changed.

Select the text that you want to format.
Click on Home tab.
Change  line spacing by line spacing option.

Creating a bullet or number list

Items in a list can be separated by beginning each item with a bullet or number.

Select the text to be formatted.
Click on Home tab.
Click on a list button.
Bullets button can be clicked to create a bulleted list.

Indenting a Paragraph

To make paragraphs in document,text can be indented.

Select the paragraph needed to be indented.
Click on Home tab.
Click on increase indent to indent the left edge of paragraph.
To decrease the indent,click on decrease indent.
Find and replace text
Click at the beginning of document.
Click on Home tab.
Type the text you want to find.
Type the text you want to use,in place of the text you typed.
Click on Find.
Inserting Symbols
Click on the location where you want a symbol to appear.
Click on insert.
Click on symbol.

Deleting  text in document
You can delete the text that is no longer needed.
Select the text that you want to delete.
Press the delete key from keyboard to remove the text.
Undo Feature
Click on open undo icon on quick access toolbar.
Word reverses the effects of the last change.
Copy and Paste
Select the text you want to copy.
Click on Home tab.
Click on copy.
Click on the location where you want to place the text.
Click on Paste.
The text will appear in the new location.
Open a saved document
Click on File tab.
Click on open button.
Recently opened documents appear on the File menu,and any of these documents can be clicked to open them.
Saving a document
Click on File tab.
Click on Save as button.


Spelling and Grammar mistakes

All the spelling and grammar errors in document can be found and corrected.

Click on Review tab.
Click on spelling and grammar button.

There is an area which displays misspelled word or grammar error.
There is also an area which displays suggestions for correcting error.

Computers-Boolean Algebra Laws/Theorems

Boolean Algebra Laws/Theorems:

1.Indempotence Law

2.Involution

3.Complementarity Law

4.Commutative Law

5.Associative Law

6.Distributive Law

7.Absorption Law

8.De Morgan's Law

1)Indempotence Law

X+X=X

X.X=X

2)Involution

=

X=X

3)Complementarity Law

     _

X+X=1

    _

X.X=0

4)Commutative Law

X+Y=Y+X

X.Y=Y.X

5)Associative Law

X+(Y+Z)=(X+Y)+Z

X.(Y.Z)=(X.Y).Z

6)Distributive Law

X.(Y+Z)=X.Y+X.Z

X+(Y.Z)=(X+Y).(X+Z)

7)Absorption Law

X+X.Y=X

X.(X+Y)=X

8)De Morgan's Theorem

____  _  _

X+Y=X.Y

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