Transmission Media -Cont

Example 7.1

Imagine a signal travels through a transmission medium and its power is reduced to half. This means P  2=(1/2)P  1. Calculate Attenuation? Solution: -10log  10(P  2/ P  1)= 10log  10(0.5 P  1/ P  1) =10(-0.3)= -3 dB    Distortion o    Distortion means that the signal changes its form or shape o    Distortion occurs in a composite signal o    Signal changes its form or shape o    Occurs in a composite signal, made of different frequencies o    Each signal component has its own speed    NOISE o    Thermal Noise -Due  to  random  motion  of  electrons  in  a  wire  that  creates  an  extra  signal  not originally sent by TX o    Induced Noise -Comes from sources like Motors and Appliances o    Crosstalk: -Effect of one wire on another o    Impulse Noise -Spike (A signal with high energy in a very short period of time) that comes from power lines, lightening etc,