Attenuation
With The increase in the distance the energy of signal decreases.This energy loss is called Attenuation.This Energy loss is due to the Resistance of the Transmission wire which gets warm when signals are passed through them.This energy loss is Frequency Dependent.To re-boost these weak signals amplifiers are used and signal can travel long distance.
Delay Distortion
This is caused by the speed mismatch of different signal carrying devices.the signal do not arrive at the same time.e.g. in a network switch and hub can be used.data transmission in switch will be fast as compared to data transmission from hub.this may cause late delivery of some data frames and may result in distortion of signal.
Noise
It is the form of unwanted energy other than the transmitter.it can be due to the following reasons:
i)Thermal Noise due to movement of electrons in conductor.
i)Thermal Noise due to movement of electrons in conductor.
ii)due to spikes on power line.
iii)Cross Talk caused by closed inductive coupling.
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