Communication System And Communication Working

Communication:

It is a process of exchanging the information from one place to another place. The term communication refers to the sending, receiving and processing of information by electronic means.

History:

As the time passes and decades runs over, the technology of the communication gets upgraded. Day by day many new inventions adds strength to the field of communication and also makes the way of human living easy and simple. It started up with the wire telegraphy which was first introduced for the military purposes during the first world war. Soon after that, it was bought to the commercial uses. Then this wire telegraphy was modified into the direct telephony which impressed a wide range of users and bought a new life to the communication sector in the world. This is the place where the sector of communication and telegraphy attained a significant place in the history. This is followed by some advanced techniques like radio communincation in the 19th century which is still in use in some undeveloped countries around the world. After that the tremendous satellite era broke up because of which antenna communication, network communication and mobile communication started its game.

1. Wire telegraphy (1840's)


2. Telephony (some decades)


3. Radio Communication (19th century)


4. Mobile, satellite, etc (Recent)

Forms of communication:

1. Radio Telephony


2. Telegraphy


3. Broadcasting (Telecasting)


4. Point to point communication


5. Mobile communication


6. computer communication


7. RADAR


8. Navigation

Terms: Message, information, signal, data, waves, having some meaning, channel, noise, distortion. Interference is unwanted signal, recording, decoding, modulation, demodulation, encording.

Basic Communication Systems:

The basic communication system consists of several building blocks in it such as transmitter, receiver and channel. Transmitter and receiver are the two main blocks which are interconnected by the channel block. For a best communication system, the given data in the transmitter side should be properly distributed over the receiver side without much distortion.

Transmitter:

Transmitter is a device which transmittes the messages suitable for transmission.

Channel:

Channel is a medium or path through with the seriel can propagates (passes) from transitter to receiver. There are two types of chanels namely, wireless and wire lines(optical fibre).

Receiver:

It's a device with receives the transmitter signal from the channels.

Modulation:

Modulation is nothing but the convertion of low frequency signal level to high frequency signal level. It is simply converting low frequency into high frequency. Low frequency signals is telephonw voice signals which lies between 30Hz to 3100Hz. The basic definition of the modulation defines the convertin of low frequency signal into high frequency signal. Whenever the message or information rides over the carrier signal is called modulation. Modulation is process of placing the message signal over the carrier to make it suitable for transmission over for long distance. Modulation is the process of changing some parameters (characterstics) of high frequency carrier signal in accordance with the instantaneous variation of the message signal. High frequency signal is called as the carrier signal. High frequency signal or carrier signal is categorized as amplitude, frequency and phase.

Amplitude Modulation

Amplitude modulation is the process of changing the amplitude of the carrier signal with respect to the amplitude of the message signal by keeping frequency and phase of the carrier as constant.

Frequency Modulation

It is the process of changing the frequency of the carrier signal with respect to the amplitude the message signal with respect to the amplitude of the message signal by keeping amplitude ad phase of the carrier as constant.

Phases Modulation

It is the process of changing the phase of the carrier signal with respect to the amplitude of the message signal by keeping amplitude and frequency of the carrier as constant.

Need for modulation:

To transmit low frequency over long distances. And also because of the antenna size. By doing the modulation the antenna size is reduced. It increase the signal to noise reduced. Bandwidth of the modulation signal may be made smaller or larger than the original.