Data communications (Datacom) is the engineering discipline concerned with communication between the computers. It is defined as a subset of telecommunication involving the transmission of data to and from computers and components of computer systems. More specifically data communication is transmitted via mediums such as wires, coaxial cables, fiber optics, or radiated electromagnetic waves such as broadcast radio, infrared light, microwaves, and satellites. Data Communications = Movement of computer information by means of electrical or optical transmission systems Information can be represented using analog signals
Analog signals cannot be manipulated easily
Analog signals must be digitized for computer processing
They must also be presented in binary form for computer processing
Figure1.1 Data Transmission Using Analog Technology
Unit of information: A byte consists of 8 bits that is treated as a unit or character. The bandwidth is a property of a medium: It is the difference between the highest and the lowest frequencies that the medium can satisfactorily pass. The analog bandwidth of a medium is expressed in hertz; the digital bandwidth, in bits per second.
Signals: Analog or digital Signals can be analog or digital. Analog signals can have an infinite number of values in a range; digital signals can have only a limited number of values. Analog signal has infinitely many levels of intensity (infinitely many values, continuous values) over a period of time. Digital signal has only a limited number of defined values (discrete values) say, 0,1.
Figure 1.3 Analog and Digital Signal
Phase: It describes the position of the waveform relative to time zero.
Figure 1.4 Phase
Figure 1.5 Sine Wave
Figure 1.6 Amplitude
A signal needs to pass through a transmission medium. A transmission medium may pass some frequencies, may block few and weaken others. This means when a composite...
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