WEEK 4: DATA COMMUNICATION

Data Communication

We all are acquainted with some sorts of communication in our day to day life. For communication of information and messages we use telephone and postal communication systems. Similarly data and information from one computer system can be transmitted to other systems across geographical areas. Thus data transmission is the movement of information using some standard methods. These methods include electrical signals carried along a conductor, optical signals along an optical fibers and electromagnetic areas.
Suppose a manager has to write several letters to various clients. First he has to use his PC and Word Processing package to prepare the letter, if the PC is connected to all the client's PC through networking, he can send the letters to all the clients within minutes. Thus irrespective of geographical areas, if PCs are connected through communication channel, the data and information, computer files and any other programs can be transmitted to other computer systems within seconds. The modern form of communication like e-mail and Internet is possible only because of computer networking.

Type Of Signal

Analogue Signal

Human voice
It is formed by continuously varying voltage levels that create wave that can be grasped by an analogue transmitter like microphone.
Represent by thier character the wave.
Frequency-number of complete wave circle.[Hertz(Hz)]
Amplitude-wave height measured by voltz(v)/decibel(dB).
Analogue signal is transmitted

Digital Signal

Digital signals are signals that are represented by binary numbers, "1" or "0". The 1 and 0 values can correspond to different discrete voltage values, and any signal that doesnt quite fit into the scheme just gets rounded off. Digital signals are sampled, quantized & encoded version of continuous time signals which they represent. In addition, some techniques also make the signal undergo encryption to make the system more tolerent to the channel.

the hidden :)