Components of Data Communication : Many early forms of communication were gestures, writings and depictions on cavo walls. With the development of language and the use of symbols, papyrus and paper facilitated recording communication for later use. The desire to communicate further and go beyond the geographical boundaries inspired man to develop different techniques Some of these techniques were based on story telling through gesture, animation and sound.
In 1948, Claude Shannon,who worked for the Bell Telephone Company in United States of America, had proposed a model of communication as shown in Figure. This serves as a basis for explaining the chain of communication since that time.
Oral communication between two people, the model is applied as follows:
Source: the brain
Message: the idea, the thought
Sender: the transmitting device, the mouth
Channel: the medium the message travels over, air
Receiver: the receiving device, the ear
Destincation: the brain
Components of Data Communication Systems
A data communication system consists of the following:
a) Transmitter or Sender of Data
These may be terminals, computers, mainframes, etc.
It is the medium through which the data is being transmitted. The various types of media are cables, radio frequency waves, microwave, fibre optic cables and infrared waves.
As the name implies, it is the device which receives the transmitted data. These are printers, terminals, mainframes, computers, cell phones, etc.
In figure, the transmitter-medium interface and the medium-receiver interface have been shown by dotted lines.The transmitter may be a device which transmits a signal in such a format that is not compatible with the medium. Similarly, medium m ter provide a signal in unacceptable format to the receiver. Hence, the signal from one to another as per the requirement.
Data Circuit Terminating Equipment (DCE)
It is also known as Data Communication Equipment. DCE is the equipment that interface the source and the medium and the medium and the source. DCE includes modems DSUs and CSUs, and Front End Processors (FEPs). Each device is located at both ends of a communication circuit.
Data Terminal Equipment (DTE)
The equipment is a data communication system terminal that inputs and outputs data.h general, data terminals have a human-machine interface.A typical example of DTE is an ATM of a bank. In other words, DTE is the computer transmitting and receiving equipment, including a wide variety of dumb terminals (terminals without embedded intelligence in the form of programmed logic),intelligent terminals and in the form of host computers such as mainframes and minicomputers.
In a wider sense, we understand that a transmitter or a sender may be a terminal (computer)with communication and application software which controls the terminal and processes data. There may be more than one terminal connected to the sender. Communications software is generally embedded in the computer operating system. Alternatively, it can take the form of a systems task under the control of the computer’s operating system. The role of communications software is to assist the operating system in managing local and remote terminal access to host resources, to manage security and to perform certain checkpoint activities. Figure shows the components of a data communication system with devices such as DTE, DCE and medium. Here, the DTE, the DCE and the medium have been replaced by a computer with communication software,MODEM (Modulator demodulator ) and a telephone line respectively.