Digital signalprocessingpart1 : Digital signalprocessingpart1
Introduction : Introduction Types of communication technologies
Analog communication
Digital communication
Basic communication system : Basic communication system link1 link2 A B
Slide 4 : The communication between A and B is as fallows:
A sends the data through the link1 and B sends the data from link2 .
In link1 A is the transmitter and B is the receiver.
In link2 B is the transmitter and A is the receiver .
The air/wires are the channel .
Examples : : Examples : Walky talky
Cellular mobile
Telephones
Radio
T.V
Radar systems
Network connections
Internet
Broad band
Fax machines etc.
Analog communication : Analog communication Uses analog signals
Def: “ an analog signal is continuous both in time and amplitude”. amplitude Time Wave form X-axis Y –axis
Wave forms in A.C : Wave forms in A.C Here some of the wave forms used are
Sinusoidal
amplitude
sin(0)=0
sin(90)=1
sin(180)=0 sin(270)=-1 0 90 180 Angle in degrees
Slide 8 : Cosine
cos(0)=1
cos(90)=0
cos(180)=-1
0 90 180
Tangential/ramp
tan(0)=0
tan (45)=1
Amplitude tan(90)= Angle in degrees 8
Examples for analog systems : Examples for analog systems Am /Fm Radios
Walky talky
Multi meters
Telephone system
LDR .
Digital communication : Digital communication It uses digital signals
Def:”discrete both in time and amplitude” 1 2 3 4 5
4
3
2
1 Discrete signal
to
Coded signal /digital signal
Wave forms in digital communication : Wave forms in digital communication Train of pulses /impulse wave
1
amp
time
Unit step 0 1 2 3 4 5 6 7 3
2
1
0 0 1 2 3 time
Slide 12 : Triangle
amp
time
Rectangle
Amp
time
Examples for digital systems : Examples for digital systems Logic gates
Digital meters
Digital cams
Cellular phones
Digital watch
Modems
Routers
Keyboards etc.
types communication : types communication Simple
Ex:broadcasting a message
Half duplex
Ex: sms to a friend
Full duplex
Ex: voice communication