Communications Systems
-
Upload
ariel-joseph-maniclang -
Category
Documents
-
view
214 -
download
0
description
Transcript of Communications Systems
![Page 1: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/1.jpg)
COMMUNICATION SYSTEMS
![Page 2: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/2.jpg)
Elements of Communication Sytems!
The Source!
The Channels!
Types of Modulation!
Signal Bandwidth
OUTLINE
![Page 3: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/3.jpg)
ELEMENTS OF
COMMUNICATION SYSTEM
SOURCE TRANSMITTER RECEIVER DESTINATION
CHANNEL
![Page 4: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/4.jpg)
ELEMENTS OF
COMMUNICATION SYSTEM
SOURCE* TRANSMITTER RECEIVER DESTINATION
CHANNEL
• need to be in FORM to pass through CHANNEL
!• to employ
*SOURCE
TRANSMITTER and RECEIVER
![Page 5: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/5.jpg)
ELEMENTS OF
COMMUNICATION SYSTEM
`
SIGNAL MODULATED CARRIERS
about 300 Hz - 3 kHz
High-Fidelity Music
about 20 Hz - 20 kHzFrequency (Hz)
!
"
A N A L O G
about 4.2 Mhz
⇛SOURCEVoice
Video (TV)
![Page 6: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/6.jpg)
ELEMENTS OF
COMMUNICATION SYSTEM
SOURCE
SIGNAL FREQUENCIES
Voice
Alphanumeric
ANY Bandwidth !!!DEPENDENT: !□ Transmission (bps) □ Method to convert binary 1’s & 0’s to electrical signal
Frequency (Hz)!
"
D I G I T A L
Video
⇛
![Page 7: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/7.jpg)
ELEMENTS OF
COMMUNICATION SYSTEM
CHANNEL (a path for transmission of signal)
TYPES
Modulated Carriers !
• information signal • modulating signal • baseband
BASEBAND Frequency spectrum of information signal
"⇛
Carrier Signals
!
Analog
Digital
Carrier Frequency HIGHER THAN Information Signal
CONDUCTOR PAIRS (DIRECT)
FIBER OPTICS
FREE SPACE
RADIO LINK !
• Not OK for DIRECT LINK • Needs HIGHER ANTENNA • INTERFERENCE • Needs CARRIER
![Page 8: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/8.jpg)
• Process by which some characteristics of the carrier wave is varied in accordance with an information-bearing signal.$
• Done at Transmitter (TX)!• Demodulation (Detection) done at Receiver (Rx)$!
MODULATION
! Carrier is Sine Wave!
e(t) = Ec sin (wct + θ)!!
where e(t) = instantaneous voltage as a function of time$$ Ec = peak voltage (Amplitude)$$ wc = frequency in radians per second$$ t = time in seconds$$ θ = phase angle in radians$
![Page 9: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/9.jpg)
SIGNAL BANDWIDTH
!I = ktB!
! where I = amount of information to be sent!! k = a constant dependent on modulation type (i.e. AM, FM, PCM etc.)!! t = time available!! B = channel bandwidth$
Hartley’s Law
![Page 10: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/10.jpg)
FREQUENCY DIVISION MULTIPLEXING (FDM)
! Combining of two or more information signals.$
Multiplexing
! Process of dividing available frequency range among signals.$
Frequency Division Multiplexing (FDM)
![Page 11: Communications Systems](https://reader034.fdocuments.us/reader034/viewer/2022051621/55cf91a4550346f57b8f2b8a/html5/thumbnails/11.jpg)
TYPES OF MODULATION
SOURCE* TRANSMITTER RECEIVER DESTINATION
CHANNEL
• need to be in FORM to pass through CHANNEL
!• to employ
*SOURCE
TRANSMITTER and RECEIVER