统计时分复用.ppt

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Data munications
Part Two munications
Chapter 8 Multiplexing
Main Contents
frequency-division multiplexing FDM 频分复用
Synchronous Time Division Multiplexing 同步时分复用
Statistical Time Division Multiplexing 统计时分复用
Asymmetrical Digital Subscriber Line ADSL
不对称数字用户线路
Key Points
FDM, TDM
FDM system
synchronous TDM and statistical TDM
ADSL
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Multiplexing 复用,多路复用
The mon forms of multiplexing :
frequency-division multiplexing (FDM)
Time-division multiplexing (TDM)
★1. FDM and TDM 频分复用和时分复用
a
b
b
c
a
t
c
d
frequency-division
Time-division
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Frequency Division Multiplexing P243
FDM
Used for analog signals
Each signal is modulated to a different carrier frequency
Each requires a certain bandwidth centered around the carrier frequency-channel
The channels are separated by guard bands
. broadcast radio and cable TV
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Frequency Division Multiplexing Diagram
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FDM of Three Voice band Signals
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FDM System
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(USA)
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Wavelength Division Multiplexing波分复用
Multiple beams of light at different frequency
Carried by optical fiber
Each color of light (wavelength) carries separate data channel
1997 Bell mercial systems of 160 channels of 10 Gbps now available