Communication system
Communication
Communication is that the process of transfer of data from sender to receiver.The transmitter converts the knowledge into signals suitable for the channel .
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| Fig. Communication system |
While the signals propagate through the channel , noise signals (unwanted signal) arise. These signals along side noise will reach the receiver end, where message signal is filtered from the transmitted signal along side noise.
To some extent, the noise signals are often filtered out and therefore the message signal are often reproduced.
Basically there are three elements in comm-unication system-
- Transmitter
- Communication channel
- Receiver
1.Transmitter Unit
The information can't be transmitted in its raw format through the channel. Transmitter unit is used to convert raw information into the format that's understandable by the channel . Different methods like modulation and coding could even be used hoping on the requirement . Mobile phones and AM radio transmitters are variety of the foremost familiar transmitters. Modulation is employed to superimpose a coffee frequency message signal on to a high frequency carrier to protect the signal from getting dispersed.
2.Communication channel
Communication channel is defined because the medium through which the signal is send from transmitter to receiver. When signal is propagated through the channel, it gets suffering from noise. And channel attenuation degrades the signal strength, so signal power decreas with distance. In radio communication systems, air is that the medium and in satellite communication systems, both air and vacuum are the medium.
3.Receiver
Signals sent through the channel reaches the receiver, where it's decoded or demodulated to extract the message. Since channel attenuation degrades the signal power, amplifier is employed at the receiver to catch up on the transmission losses. Both selectivity and sensitivity of a receiver should be high only then the message signal are often extracted from the received signal.
Communication System Termino-logy
1.Signal
Any audio or video or audio-visual generated for instance can't be directly transmitted. It first must be converted into an electronic form. This electronic form is a ‘Signal’. Since electronics operate in the binary system i.e. a combination of 1s and 0s only (generally 1 denotes ‘on’ or ‘high’ and 0 denotes ‘off’ or ‘low’), the whole audio-visual is converted into a binary form. This binary form within the electrical medium may be a ‘Signal’.
2. Amplitude
The greatest distance that a wave, especially a sound or radio emission , moves up and down.
3.Wavelength
The wavelength of a sinusoi-dal wave is that the distance between two particles having an equivalent amount of displacement and both are in phase with one another .
4.Frequency
The frequency of a wave is that the number of waves passing some extent in space per unit time. It is basically the reciprocal of the period of time required by a wave to hide a unit distance.
5. Bandwidth
The bandwidth of a sign is that the difference between the very best and therefore the lowest frequencies carried by the signal.
6.Modulation
Any signal to be transmitted consists of variety of varying frequencies and can't be directly transmitted by the transmitter and is therefore superimposed with a carrier signal before being transmitted. This is the ‘Modulation’ of the signal.
Modulation of the signal is in two ways.
- Amplitude Modulation
- Frequency Modulation
- Phase Modulation
7.Demodulation
The modulated signal sent by the transmitter is received by the receiver and wishes to be converted to its original format before it are often studied. This process is Demodulation. It is basically the reverse of Modulation.
8. Attenuation
When a sign is transmitted through the electronic medium over long distances it loses its quality and strength thanks to dissipation and wastage of energy naturally. This is the ‘attenuation’ of the signal. Using the various methods we prevent or minimize the deterioration of the signal.
9. Transducer
A transducer is any device that converts any physical variable like force, movement etc to an signal and thus gives an appropriate output for an equivalent .
For example, whenever you employ your smartphone and choose a worth on its screen the processor of the phone converts the pressure on the screen thanks to your touch into a signal. This is an example of a ‘Transducer’.
10. Amplification
The process of boosting the amplitude of a signal is “amplification”.
For example, whenever you speak on a mic, your voice is amplified and audible at a farther distance.
In this process, only the amplitude of the signal increases. There is no fundamental change to the first content of the signal.
11. Repeater
Any signal transmitting over an extended distance is liable to lose its quality and strength.
To beat this issue we use a “repeater” to facilitate transmission of the signal over very long distances.
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