Wednesday, October 22, 2014

Telecommunication basic

What is modulation?

modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted.

What is modulation index?

The modulation index (or modulation depth) of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level. It is defined differently in each modulation scheme. See: Amplitude modulation index. Frequency modulation index.

Wednesday, September 10, 2014


2.Explain the operating modes of 8255 peripheral interface ?

Answer: One

1.Draw the internal architecture of 8086 microprocessor.

AX = Accumulator Register

BX = Base Register

CX = Count Register

DX = Data Register

SP = Stack Pointer

BP = Base Pointer

IP = Instruction Pointer

  Instruction Queue
Index Registers -
SI = Source Index
DI = Destination Index
Segment Registers -
CS = Code Segment
DS = Data Segment
SS = Stack Segment
ES = Extra Segment

Transistor: Transistor consists of three layer either two p-types and one n-type or two n-type one p-type. Two p-type and one n-type transistors is known as PNP transistor and two n-type one p-type transistors is known as NPN transistors. Transistor has three terminal emitter, collector and base.

Figure: Transistor
Transistor configurations: 1.Common-base. 2. Common-emitter.  3. Common-collector.
Transistor has three modes: 1. Active mode for amplifier operation. 2. Saturation mode for switch operation. 3. Cutt-off mode for switch operation.
Transistor two types:  1. BJT 2. FET

BJT: A bipolar junction transistor is a bipolar device in which the current flow between two terminals (the collector and the emitter) is controlled by the amount of current that flows through a third terminal (the base). Input is low and output is lower than input.

FETThe field-effect transistor is uni-polar device that uses an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material.Input is high output is higher then input.

Semiconductor: The combination of p-type and n-type material is called p-n junction and it is known as semiconductor.


My You Tube channel is here.

Basic Electrical

Current: Current is the flow of electron.


Battery: Battery is a storage of electron.

Important factors of Electric energy

1.Easily covert-able
Electric energy can easily converted into other form.
Example:If we flow current through a wire we can easily found heat.

Electric machine can easily start and off by pushing a switch.

Electric energy can easily transport from one place to another through
a wire.

4.Low cost
Electric energy is cheaper than other forms of energy.

Electric do not create any smoke or fums.

Energy source

Sun is a open source of electric energy. The heat of sun can easily
converted into electric energy.
Low maintenance cost.
Open source.
Keep environment safe.
Requires a large space.
Initial cost high.

Water can converted into electrical energy using turbine.
Turbine drives alternator and produce electric energy from mechanical energy.
Low maintenance cost.

3. Fuel
Figure: IC engine.
Fuel converted into mechanical energy by using Steam engine, internal combustion

4.Nuclear energy

Figure: Fusion.
Nuclear energy produce large number of current.
It produce current by fusions of uranium and other fusion-able material.

Power station

1.Steam power generation
 A power station that produces electrical energy from heat energy of coal is known as steam power station.
Steam turbine runs the alternator which convert mechanical energy of the turbine into electrical energy. This type of power station situated where coal and water are available.


The fuel used it is cheap.
Less initial cost comparing other generating station.
It can be installed at a place where coal exists. The coal can be transported to the site(plant) by rail or road.
The cost of generation is less then diesel power station.                                                                                                             


It pollutes the atmosphere due to the production of large amount of smoke and fumes.
It is costlier in running cost as compared to hydroelectric plant.

Source:Principles of power system by V.K. Metha & Rohit Metha.                                                                

Friday, August 15, 2014

Download software free.

My You Tube channel

To download software go to this link.

Adobe Dreamwaver CS6

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Youtube video downloder

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Adobe photoshop portable Cs4

Download link is here.

Adobe photoshop Cs8 

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Camtasia studio   

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Google talk  

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Mozilla Firefox

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Team viewer  

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Dreamwaver8   download link is here

Xampp  download link is here

Thursday, August 14, 2014

Digital Bangladesh.

Digital means using a system of receiving and sending information as a series of the number of  zero and one.
Showing that an electronic signal is there or not there.The use of digital information and technology has been playing a vital role in the field of communication in the 21st century due to globalization.Bangladesh is resounding with target of achieving of Digital Bangladesh.
The present Al democratic government has declared the "vision 2021" in the election manifesto which targets establishing of a resourceful and modern country by 2021 through effective use of information and communication technology-a "Digital Bangladesh".

How to open a Bank account.

  1. At first you need to take two copies of recent passport size photographs,national id card/student id card.
  2. You need to take someone who has an account to this bank.
  3. Now you can go to the branch of the bank where you want to create bank account.
  4. Bank employee give you a form you need to fill up this form.
  5. Finally you need to deposit some money in favour of your account.

Twitter details.

How to tweet on twitter  

At first create your twitter account by following the instruction given below:

  1. go
  2. Click at sign up for twitter.
  3. Give your required information and click create my account.
  4. Verify your email address.
  • Now log in your twitter account.
  • Click at Compose new Tweet from the right sight top.
  • Now write something and click at tweet.You can also give link with your message.
  • For any help comment below.