Network Architecture

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Network Architecture
Customer terminals 20 Outside plant, cables
29 Switching equipment 25 Multiplexing and
Transmission equipment 15 Buildings, land, other
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Network Types
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Trade-off Between Switching and Transmission
Costs in Network Architecture
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Trade-off Between Switching and Transmission
Costs in Network Architecture
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Network Types
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Concept of a Homing Plan
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Subscriber Loop Plant (N. America)
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Subscriber Loop Plant (UK)
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Subscriber Loop Plant
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Twisted Pair Cable
Each change of 3 gauge numbers is a factor of 2
in wire area (cross section), this a factor of 2
in resistance / unit length
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Inductive Loading - Load Coils
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Inductive Loading - Lumped Load Coils
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Effect on Transfer Function of Twisted Pair
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Example Calculation of Cutoff Frequency
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Subscriber Line Signalling
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Address Signalling
Dial Pulsing
Dual-Tone Multi-frequency (DTMF)
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DTMF Receiver
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2-Wire to 4-Wire Conversion

• Any telephone call undergoes 2W-4W conversions
• - from the phone (4W) to the subscriber line (2W)
  
• - from the subscriber line (2W) to the network
  interface (4W)

4W
4W
2W
4W
2W
Overall structure of any phone connection
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2W to 4W conversion The Hybrid Coupler Circuit
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2W to 4W conversion The Hybrid Coupler Circuit
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Electronic Hybrid Coupler
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Concept of Hybrid Return Loss
Echo return loss (ERL) average attention of
power reflected at the 2W-4W interface Singing
Return Loss (SRL) minimum attenuation to
reflected power at any frequency coming back
from the 2W-4W interface
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Psophometric and C Weighting Noise Filters
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Example