#)Hai friends in this article let us discuss about the basic of the communication.

#)As a matter of fact communication is just a transfer of message and even the way two peple convers is a form of communication

#)Communication is the transfer of information from one place to another place.

#)The image below represents a simple way of communication

#)Distribution of the data, message from one location to another location with high reliability and security is the major role of communication system

Elements of Communication System

#)Communication System consist of the following components which acts together to accomplish information transfer or exchange.These includes

1)Input Transducer

2)Transmitter

3)Channel

4)Receiver and

5)Output Transducer

#)The above diagram represents the bloack diagram of the communication system and let us explain each block in detail

#)The process of the basic communication is shown in the image below

1)Input Transducer:

#)The input message by a source must be converted by a transducer to form suitable for the particular type of communication

#)In electrical communication,speech waves are converted to voltage variation by a microphone

2)Transmitter:

#)The transmitter processes the input signal to produce a transmitted signal suited to the characteristics of the transmission channel.

#)Signal Processing for transmission always involve modulation.In addition to modulation, other functions performed by the transmitter are amplification,filtering and coupling the modulated signal to the channel

3)Channel:

#)The channel can have different forms....

i)  The atmosphere or free space

ii) Coaxial Cable

iii)Fiber optic , Wave Guide etc.

4)Receiver:

#)The receiver function is to extract the desired signal from the received signal at the channel output and to convert it to a form suitable for the output transducer.

#)Other functions of the receiver are amplification(the received signal may be extremely weak), demodulation and filtering

5)Output transducer:

#)The function of the output transducer is to convert the electric signal at its input into the form desired by the system user.

#)Loudspeaker, act as a output transducer to convert the received electrical signal to voice signal

Analog and Digital Communication

#)There are many kinds of information sources, which can be divided into two distinct message catoegaries,namely analog and digital

1)Analog Communication:

#)This form of communication uses analog messages.

#)An analog message is a physical quantity that varies with time, usually in a smooth and continuous fashion.

#)Since the information resides in a time-varying waveform, an analog communication system should deliver this waveform with a specific degree of reliability or fidelity

Advantages:

i)Smaller bandwidth is required.

ii)Synchronization problem is relatively easier

Disadvantages:

i)Expensive analaog components: L & C.

ii)No privacy i.e security is not high.

iii)Cannot merge data from different sources.

iv)No error correction capability

2)Digital Communication

#)This form of communication uses digital messages.

#)A digital message is an ordered sequence of symbols selected from a finite set of discrete elements.

#)Since the information resides in discrete symbols, a digital communication system should deliver these symbols with a specified degree of accuracy in a specified amount of time.

Advantages:

i)Inexpensive digital circuits.

ii)Privacy preserved(data encryption).

iii)Can merge different data(voice,video and data) and transmit over a common digital transmission system.

iv)Error correction is possible by coding

Disadvantages:

i)Larger bandwidth is required.

ii)Synchronization problem is relatively difficult

What is modulation?

#)It is the process by which the characteristics of the carrier wave is varied in accordance with the instantaneous value of the message signal.

#)The below image represents the block diagram of the modulation process

#)The characteristic of high frequency carrier, which has been modified to carry the lower frequency information, this process is called modulation.

#)Once this information is received, the lower frequency information must be recovered from the high frquency carrier , this process is called demodulation

Need of Modulation

1) Easy of radiation, as the signals are translated to higher frequencies, it becomes relatively easier to design amplifier circuit as well as antenna system at these increased frequencies

2)To overcome hardware limitations

3)Transmitting such lower frequencies reqire antennas with miles in wavelength

4)Modulation to reduce which result in optimization to Signal to Noise Ratio(S/N)

5)To minimize the effects of interference

6)For multiplexing and frequency assignment

7)For efficient radio transmission

Classification of Modulation

I)Classification Based by the nature of modulating signal

i)Analog Modulation

#)The modulating signal is an analog signal

#)Examples:AM(Amplitude Modulation),FM(Frequency Modulation),PM(Pulse Modulation),Pulse Amplitude Modulation(PAM)

ii)Digital Modulation

#)The modulating signal is a digital signal

#)Examples:ASK,FSK,PSK

2)Classification Based by the nature of carrier

i)Continuous Wave (CW) Modulation

#)Carrier is a sinusoidal wave

#)Eg.,AM,FM,ASK,FSK,PSK

ii)Pulse Modulation

#)Carrier is a train of pulse

#)Eg., PAM,PWM,PPM

Wired and Wireless Form of Communiation

i)Wired Communication

#)Radio waves are the forms of electromagnetic radiation, the energy is conveyed by 'waves' of magnetic and electric fields

#)In a wire, these waves are induced and guided by an electric current passing along with electrical conductor,but that is not the only way of propagating electromagnetic(EM) waves.

#)By using a very strong electrical signal as a transmitting source and EM wave can be made to spread far and wide through air adn this is a principle of radio

#)The radio waves are produced by transmitters,which consist of a radio wave source connected to some form of antenna

#)The image below shows the wired telephone communication

ii)Wireless Communication:

#)The transmission channel is the main issue of communication system and conventionallyit is the set of hard-wired cables that connect all the lines of the wire line phone

#)In wireless sytems,the cables are replaced by free space, but only at the cost of reqiring the erection of antennas that allow the line of sight communication

#)The picture below explains the wireless form of cellular communication

Advantages:

1)Freedom from land acquisation

2)Ease of communication over different terrain

Disadvantage:

1)Bandwidth allocation is extremely limited

2)Atmospheric effects

3)Transmission path needs to be clear

4)Interference and efficiency propagation

5)Restrictive costs

These are some of the basic topics of communication.If u find any error u just reply and i will correct it.Thank you