Modulation Sender changes the nature of the signal in a way that the receiver can recognize Similar to radio: AM or FM Digital transmission; encodes the values o or in the signal. >)It is also possible to encode multi-valued symbols Amplitude modulation: change the strength of the signal, typically between on and off 》 Sender and receiver agree on a“rate” >)On means 1, Off means 0 Similar frequency or phase modulation Can also combine method modulation types. 6
6 Modulation Sender changes the nature of the signal in a way that the receiver can recognize. » Similar to radio: AM or FM Digital transmission: encodes the values 0 or 1 in the signal. » It is also possible to encode multi-valued symbols Amplitude modulation: change the strength of the signal, typically between on and off. » Sender and receiver agree on a “rate” » On means 1, Off means 0 Similar: frequency or phase modulation. Can also combine method modulation types
Amplitude and Frequency Modulation 00110011000111000110001110
7 Amplitude and Frequency Modulation 0 0 1 1 0 0 1 1 0 0 0 1 1 1 0 0 0 1 1 0 0 0 1 1 1 0 0 1 1 0 1 1 0 0 0 1
The Frequency domain A(periodic) signal can be viewed as a sum of sine waves of different strengths. >)Corresponds to energy at a certain frequency Every signal has an equivalent representation in the frequency domain > What frequencies are present and what is their strength(energy) Again: Similar to radio and Tv signals lme requency 8
8 The Frequency Domain A (periodic) signal can be viewed as a sum of sine waves of different strengths. » Corresponds to energy at a certain frequency Every signal has an equivalent representation in the frequency domain. » What frequencies are present and what is their strength (energy) Again: Similar to radio and TV signals. Time Frequency Amplitude
Signal= Sum of Waves +13X +0.56X A∧ +1.15X 9
9 Signal = Sum of Waves = + 1.3 X + 0.56 X + 1.15 X
Why Do We Care? How much bandwidth can I get out of a specific wire(transmission medium)? What limits the physical size of the network? How can multiple hosts communicate over the same wire at the same time? How can I manage bandwidth on a transmission medium? How do the properties of copper, fiber, and wireless compare? 10
10 Why Do We Care? How much bandwidth can I get out of a specific wire (transmission medium)? What limits the physical size of the network? How can multiple hosts communicate over the same wire at the same time? How can I manage bandwidth on a transmission medium? How do the properties of copper, fiber, and wireless compare?