Communication system
-
Upload
kelly-mccarty -
Category
Documents
-
view
31 -
download
0
description
Transcript of Communication system
![Page 1: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/1.jpg)
Communication system
SourceSource
encoding
Channel
encoding
Line
encoding
Modulation
Channel
ReceiverSource
decoding
Channel
decoding
Line
decoding
Demodulation
![Page 2: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/2.jpg)
Distortion
Amplitude distortion Phase distortion
![Page 3: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/3.jpg)
Amplitude response of a telephone channel
Insertion loss=10log10P0/P2
P2=Power delivered to a load by the channel
P0=Power delivered to the same load without channel
![Page 4: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/4.jpg)
Envelope delay and Phase response of a telephone channel
Envelope delay is the derivative of the phase shift
![Page 5: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/5.jpg)
Tx
Rx
Equalizer
Threshold detector
Data
Clock (Trig ขาข��น)
Tx Channel Equalizer ThresholdDetector
RetimingCircuit
ClockExtraction
AB C D
E
F
![Page 6: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/6.jpg)
Communication system
SourceSource
encoding
Channel
encoding
Line
encoding
Modulation
Channel
ReceiverSource
decoding
Channel
decoding
Line
decoding
Demodulation
![Page 7: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/7.jpg)
Data transmission
Communication modes
Simplex Half-Duplex Duplex or Full-duplex
![Page 8: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/8.jpg)
Transmission modesAsynchronous transmission Feature : unnecessary to perfectly
synchronized Encoding Technique Used : NRZ Components : Start Bit (1 : transition from
1 to 0), Data (5-8), stop bit(1, 1.5, 2 : binary 1)
Merit : Easy-to-build Demerit : High overhead e.g. start, stop bit
1 bit, data 8 bit -> overhead = 2/10 = 20 %START BIT
5-8 BITS STOP BIT
START BIT
idle0
1
![Page 9: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/9.jpg)
Transmission modesSynchronous Transmission Feature : synchronized by sending timing
information via separate clock line or embedding in data signal
Line coding: Manchester, AMI Component : preamble (8-bit flag), Control, Data,
Control, postamble (8-bit flag) Merit : Low overhead comparing to Asynchronous
transmission. Example : preamble + control + postamble 48 bits data 1000 bits -> overhead = 48/1048 = 4.6 % data 8000 bits -> overhead = 48/8048 = 0.6 %
8-bitflag
8-bitflag
Control ControlData
![Page 10: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/10.jpg)
Transmission media
Transmission medium is the physical path between transmitter and receiver in a data transmission system.
Guided vs unguided (wireless transmission)
Characteristics and quality of data communication depend on characteristics of both media and signal.
Key concern in design is data rate and distance.
![Page 11: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/11.jpg)
Guided Transmission media Two-wire open Twisted pair Coaxial cable Fiber optic
![Page 12: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/12.jpg)
Twisted pair
![Page 13: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/13.jpg)
&
![Page 14: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/14.jpg)
Coaxial cable & connectors
![Page 15: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/15.jpg)
&
![Page 16: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/16.jpg)
![Page 17: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/17.jpg)
&
![Page 18: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/18.jpg)
Guided transmission media
Data rate Distance Typical use
Two-wire open 19.2 kbps 50 m Telephone
Twisted pair Category1-2
<2 Mbps 2-3 miles Telephone
Twisted pair Category3-6
200 Mbps 100 m LANs
Coaxial cable, ThinBaseband Single Ch.
10 Mbps 100 m LANs
Coaxial cable, ThickBroadband Multi Ch.
10 Mbps 2-3 miles LANs, Cable TV
Fiber optic 10 Gbps 100 miles Data, video, LANs, WANs
![Page 19: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/19.jpg)
Unguided transmission media
Transport electromagnetic waves without using a physical conductor
![Page 20: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/20.jpg)
![Page 21: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/21.jpg)
![Page 22: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/22.jpg)
Geostationary satellites The satellite must move at the same speed as
the earth so that it seems to be fixed above a certain spot.
Orbital speed is based on distance from the planet.
This orbit occurs at the equatorial plane and is approximately 22,000 miles from the surface of the earth.
At least 3 Satellite to cover all areas.
![Page 23: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/23.jpg)
Satellite frequency bands
Band DownlinkSat. to earth
UplinkEarth to Sat.
C 3.7-4.2 GHz 5.925-6.425 GHz
Ku 11.7-12.2 GHz 14-14.5 GHz
Ka 17.7-21 GHz 27.5-31 GHz
![Page 24: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/24.jpg)
Unguided transmission media
Data rate
Distance Typical use
Microwave
n-Gbps 20-30 miles
Building to building
Satellite n-Gbps Worldwide
Long distance
Infrared 16 Mbps 1.5 Miles Short distance
![Page 25: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/25.jpg)
ModulationsAmplitude Shift Keying ASK (OOK)
![Page 26: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/26.jpg)
BW for ASK
Nbaud is baud rate
![Page 27: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/27.jpg)
Ex. Given a BW of 10,000 Hz (1,000-11,000) for a full-duplex ASK. Find the carriers and the BW in each direction. Assume there is no gap between the bands in two directions. What is the maximum baud rate and bit rate?
![Page 28: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/28.jpg)
Frequency Shift Keying (FSK)
![Page 29: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/29.jpg)
BW for FSK
![Page 30: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/30.jpg)
EXample: Find the maximum bit rates for an FSK signal if the bandwidth of the medium is 12,000 Hz, and the difference between the two carriers must be at least 2000 Hz. Transmission is in full-duplex mode.
![Page 31: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/31.jpg)
Phase Shift Keying (PSK)
![Page 32: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/32.jpg)
PSK Constellation diagram
![Page 33: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/33.jpg)
4-PSK
![Page 34: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/34.jpg)
4-PSK Constellation diagram
![Page 35: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/35.jpg)
8-PSK
![Page 36: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/36.jpg)
BW for PSK
The same as ASK Ex. Given a bandwidth of 5000 Hz
for an 8-PSK signal, what are the baud rate and bit rate?
![Page 37: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/37.jpg)
PSK is not susceptible to the noise degradation that affects ASK, nor the BW limitations of FSK.
![Page 38: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/38.jpg)
Quadrature amplitude modulation (QAM)
![Page 39: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/39.jpg)
BW for QAM
The same as ASK and PSK.
![Page 40: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/40.jpg)
Multiplexing
multiple links on 1 physical line common on long-haul, high capacity,
links have FDM and TDM alternatives
![Page 41: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/41.jpg)
Frequency Division Multiplexing
![Page 42: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/42.jpg)
FDMSystem Overview
![Page 43: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/43.jpg)
FDM Voiceband Example
![Page 44: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/44.jpg)
Wavelength Division Multiplexing
FDM with multiple beams of light at different freq
carried over optical fiber links
![Page 45: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/45.jpg)
Synchronous Time Division Multiplexing
![Page 46: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/46.jpg)
TDM SystemOverview
![Page 47: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/47.jpg)
Data communication interfacing
DTE : Data Terminal Equipment is any device that is a source of or destination for binary digital data (PC)
DCE : Data Circuit-terminating Equipment is any device that transmits or receives data in the form of an analog or digital signal through a network (Modem)
DTE DCE PSTN DTEDCE
![Page 48: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/48.jpg)
Data communication interfacing DTE -DCE InterfacingRequirement : Use the same encoding
scheme and have common standards Mechanical characteristics : plugs,
circuits Electrical characteristics : voltage-level,
timing Functional characteristics : meaning of
each interchange circuits เช่�นขา 7 คือ Ground
![Page 49: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/49.jpg)
V.24/EIA-232 (RS 232)
Electronic Industries Association (EIA)
![Page 50: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/50.jpg)
(ISO 2110) 25-pin connector (but can be substituted by 9-pin (DB-9) : 8, 3, 2, 20, 7, 6, 4, 5, 22)
Mechanical characteristics
![Page 51: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/51.jpg)
Electrical characteristics -3 to -15 V=binary 1 or OFF condition +3 to 15 V =binary 0 or ON condition Maximum bit rate 20 kbps
0
1 1
![Page 52: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/52.jpg)
Functional specification
![Page 53: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/53.jpg)
Control SignalName To Function
Request to send
DCE DTE wishes to transmit
Clear to send DTE DCE is ready to receive
DCE ready DTE DCE is ready to operate
DTE ready DCE DTE is ready to operate
Ring indicator DTE DCE is receiving a ringing signal
Received line signal detector
DTE DCE is receiving a signal(carrier)
![Page 54: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/54.jpg)
![Page 55: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/55.jpg)
Null modem
![Page 56: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/56.jpg)
PSTN
![Page 57: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/57.jpg)
MODEMS MOdulator/DEModulator
Bandwidth 600 Hz to 3000 Hz
![Page 58: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/58.jpg)
Dial-up operation
20
DTE
![Page 59: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/59.jpg)
![Page 60: Communication system](https://reader035.fdocuments.us/reader035/viewer/2022062321/5681376e550346895d9f079c/html5/thumbnails/60.jpg)