Signal

What is a signal?

A signal is an sequential data flow which is in the form of electrical and electro magnetic wave form to transmit the data from one device to other. It may be ANALOG SIGNAL Or DIGITAL SIGNAL.

• Digital Signals

  Digital signals are discrete in nature and represent sequence of voltage pulses. Digital signals are used within the circuitry of a computer system.

• Analog Signals

  Analog signals are sequential data flow which is Continuous wave form in nature and represented by continuous electromagnetic waves.

Transmission Impairment

When signals travel a large number of distance by trough the medium they tend to deteriorate. There are many different ways to loss of the data, know as transmission impairment. Generally there are 4 types of impairment shown in below.

• Attenuation

  For the data transmit by the sender to receiver , goes through the medium. When the data is ready to transform from sender sites; the signal of the data is strong after travel some distance it may be loss their strength. This type of impairment is known as Attenuation.

• Dispersion

  It means the change of signal form/shape from one point to other.

• It occurs in composite signal made of different frequency.

• It occurs because the velocity of propagatious To guided medium varies different frequency just like copper wire, co_axial cable.

• Noise

  It is an unwanted signal that destroy our Information carrying signal. There are several types of noise which are given below.

  • Thermal Noise

    
    

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Transmission Media

The medium in which the information share between two or more devices and computer systems is sent, called transmission media. There are 2 types of transmission media is given below

• Guided Media

  All communication wires/cables are guided media, such as UTP, coaxial cables, and fiber Optics. In this media, the sender and receiver are directly connected and the information is send (guided) through it.

• Unguided Media

  Wireless or open air space is said to be unguided media, because there is no connectivity between the sender and receiver. Information is spread over the air, and anyone including the actual recipient may collect the information.

Channel Capacity

The Channel Capacity  is also known as BANDWIDTH. That means how many bits are transfer per sec. The bandwidth is denoted as (Mbps) (kbps) etc. There are another two factor of the channel capacity such as:

• Error-rate:  how many bits are incorrect per sec because of noise.

• Encoding:  The number of levels used for signaling.

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