Coaxial Architecture. Tree-and-Branch Architecture Express Trunk.

Coaxial ArchitectureCoaxial Architecture

Tree-and-Branch ArchitectureTree-and-Branch Architecture

Express Trunk

HFC ArchitectureHFC Architecture

Tap

node

HUBS

Businessesamp in building

Customer Homes

Headend (Node) Optics RX/TX

Active Device

Fiber Optic Cable

RF

Other cable outputs

Rural NetworkRural Network

Headendor Node

Optics RX/TX

LPI

LPS

1411

24 21Two-Way Tap

Four-Way Tap

Eight-Way Tap

Near Passive NetworkNear Passive Network

Directional Coupler

Splitter

17

26

29

29

Passive NetworkPassive Network

Slope Equalizer

Two Way Tap

Four Way Tap

Headendor Node Node

29

17

4

2023 17

11

26

Sample HeadendSample Headend

DT 815 Amp

out

HubEDFA

EDFA

Return TX

Return TX

DWDM

HUB

1

23

5008ET2

Public switch

Com21 Analog Video55-550 MHz

HCX comController

2 W

ayR

Fs

plit

ter

2 WayRF splitter

430MHz

DWDD

2RRX

2RRX

Connector PartsConnector Parts

BootBody

Ferrule

Types of ConnectorsTypes of Connectors

Biconic FC

D4SC

ST

Optical Loss ExampleOptical Loss Example

Optical Transmitters and Optical Transmitters and ReceiversReceivers

Coaxial Plant DesignCoaxial Plant Designand Operationand Operation

TopicsTopics

• Overview

• Optical Transmitters

• Optical Receivers

• Units of Optical Power

• Power Budget

Optical Transmitter and ReceiverOptical Transmitter and Receiver

Input ElectricalInput ElectricalSignalSignal

Input ElectricalInput ElectricalSignalSignal

Reproduced Reproduced Electrical Electrical

SignalSignal

Reproduced Reproduced Electrical Electrical

SignalSignal

Optical FiberOptical FiberOptical FiberOptical Fiber

ReceiverReceiver ReceiverReceiver

Optical SignalOptical SignalOptical SignalOptical Signal

TransmitterTransmitterTransmitterTransmitter

Optical Fiber

Laser

OpticalConnector

Drive LevelControlRF Input

Drive LevelTest Point

Optical TransmitterOptical Transmitter

BiasCurrent

ModulatedOptical Output

ThresholdCurrent

Input RF

Current

Opt

ical

Out

put P

ower

Laser Performance

Curve

Laser Drive LevelsLaser Drive Levels

Clipped Output

Bias Voltage

PreAmp

PostAmp

RFOut

Test Point

Fiber

OpticalConnector

Photo Detector

Optical ReceiverOptical Receiver

Units of Optical PowerUnits of Optical Power

Optical Power EquationsOptical Power Equations

dBm = 10 log mW

mW = inverse log (dBm/10)

+/-10dB Optical Power Table+/-10dB Optical Power Table

Optical Power (dBm) Optical Power (mW)30 1,00020 10010 10 0 1

-10 0.1 -20 0.01

-30 0.001

Power Budget FormulaPower Budget Formula

P b = T p - Rin where

P b = the Power Budget

T p = output Power of the Transmitter and

R in = required input to the receiver

Optical NodeOptical Node

NOR NRT

System RF out

Optical Node OperationOptical Node OperationOptical Node OperationOptical Node Operation

Node/Amplifier Block DiagramNode/Amplifier Block Diagram

Light Light to RFto RF

ConverterConverterLevelLevel

ControlControlAttenuatorAttenuator Tilt Tilt

GeneratorGenerator

PrePreAmpAmp

Split

ter

Split

ter

PostPostAmpAmp

PostPostAmpAmp

PostPostAmpAmp

PostPostAmpAmp

HH

LL

HH

LL

HH

LL

HH

LLCombinerCombiner

RF toRF toLight Light

ConverterConverterto RFto RF

-20 dB-20 dB Rf TPRf TP2020

dBmVdBmV

9Apad

-30 downTest Point

RFGainadjust

Opticalalarm

Opticalmonitoring T/P

Forward Optical Receivers/NOR’S

Diamond Net RF Module

Amplifier Technology


TopicsTopics

• Semiconductor Configurations in CATV–Single - Ended Amplifier–Push - Pull Amplifier–Parallel - Hybrid Amplifier

Semiconductor Amplifier Semiconductor Amplifier ConfigurationsConfigurations

2nd Harmonicplus Noise

Single - Ended AmplifierSingle - Ended Amplifier

Push - Pull AmplifierPush - Pull Amplifier

PushPullStage

PushPullStage

ADVANTAGES: High Gain and Reduced DistortionsADVANTAGES: High Gain and Reduced Distortions

Parallel - Hybrid AmplifierParallel - Hybrid Amplifier

Pin Pout

Amplifier Configurations


• Describe the most common amplifier configurations and discuss their usage.

• Identify the components for each of the amplifier configuration and explain their functions and importance.

ObjectivesObjectives

Forward Amplifier CharacteristicsForward Amplifier Characteristics

Amplifier Output TiltAmplifier Output Tilt

11dB of tilt @ 750 MHz

50 MHz 750 MHz0 dBmV

20 dBmV

10 dBmV

0 dBmV

20 dBmV

10 dBmV

50 MHz 750 MHz

Attenuator FunctionAttenuator Function

0 dBmV

20 dBmV

10 dBmV

50 MHz 750 MHz

Effect of Cable

20 dB

0 dB

10 dB

50 MHz 750 MHz

Effect of Equalizer

10 dBmV

50 MHz 750 MHz

Combined Results

Equalizer FunctionEqualizer Function

Response EqualizerResponse Equalizer

Examples of Peak to ValleyResponses. With ResponseEqualizers Installed

These are available in either bumps or traps

Equalizer SelectionEqualizer Selection

= = =

Interstage Eq Set fordesired Tilt @ Output

Secondary Eq Set Additional Tilt 50 MHz 750

MHz

20 dB

12 dB

62E750/11

11 dB

8 dB

50 MHz 750 MHz

11 dB

PostAmp

Hig

hL

owH

igh

Low

DCTP

ShortingStub to OneSecondary orDC 4-8-or 12

Pad

Hig

hL

ow

InputAtten

InputEQ

PreAmp

DCTP

ManualGain Adj.

ResponseEqualizer

Interstage Slope Eq.

ALSC Optional Plug In

InterStageAmp

DistEQ

Hig

hL

ow

Interstage Atten.

DCTP

Pad

PostAmp

Amplifier Block Diagram withAmplifier Block Diagram withALSC / AGCALSC / AGC

Forward SweepForward Sweep

SYSTEM AMPLIFIER

METER

SWEEP GEAR

Sweep System RequirementsSweep System Requirements

HeadendCombiner

Sweep Transmitter

Fiber Transmitter

Node

Fiber Optic Interconnect

AMP 1

ReferenceAmp 2

Amp 3

Amp 4

Amp 5

Amp 6

*The remaining amplifiers in the cascade are compared to the reference.

Raw SweepRaw SweepB

EF

OR

EA

FT

ER

Low Level Signal TelemetryLow Level Signal Telemetry

Frequency Response Specifics


550MHz50 MHz

Sign

al L

evel

Ideal Response

50 MHz 550MHzSi

gnal

Lev

el

Cable KinksZ Mismatch

Non Linear

Non Linear Cable Loss Non Linear Cable Loss Characteristics Characteristics

Hardware Points of ConcernHardware Points of Concern

AmplifierAmplifier

ConnectorCable

Tap

Cable

Cable

Connector

Frequency CharacteristicsFrequency Characteristics

Peak to Valley Peak to Valley

Impedance Mismatch Impedance Mismatch

RF Suckout RF Suckout

Low End LossLow End Loss

Correcting the Characteristics of Correcting the Characteristics of an Amplifier Signaturean Amplifier Signature

Correcting the Characteristics of Correcting the Characteristics of an Amplifier Signaturean Amplifier Signature

7507505454

BeforeBefore

AfterAfter

L

Automatic GainControl(AGC series

plug-in) Optional

Thermal Control(TGSC plug-in)

Optional

Thru PowerPlug

PowerSupply +24 VDC

+24 VDCTest Point

SurgeArrestor

SurgeArrestor

ACAC

Return Amplifier ModuleLER series plug-in

OptionalReturn RF

Input/

H

L

Pre-AmpAtten. Equalizer

Test Point-30 dB Resistive

Upstream

Downstream

Output

Post-Amp

Test Point-30 dB Resistive

DownstreamOutput/

UpstreamInput

H

L


+32.5/29 dBmV+38.0/31.5 dBmV

+ 43.1 dBmV33.6 dBmV

17dB-1.5

20dB-1.0dB

23dB-0.6dB

Cable Losses

@870 MHz= 1.5dB/100ft

@50 MHz=0.5dB/100ft

29dB-0.4

+48/35.5


Needs a minimumof 8dBMv at 870MHz

40dB gain

[email protected]@50

Each port has19/6.5dBmV out

Each port has15.5/12dBmV out.

14dB2.0

11dB-3.5

Input=11/17.7dB

mailto:4.5dB@870

Network Operation and Network Operation and Maintenance ProceduresMaintenance Procedures

Intermodulation Distortions


Distortion Cause: AmplifiersDistortion Cause: Amplifiers55.25MHz55.25MHz

FFss Amp Amp

110.5MHz110.5MHz

FFss++

FFss

VVCCCC2 F2 Fss

2nd Harmonic2nd Harmonic

Intermodulation DistortionIntermodulation Distortion

2nd Order DistortionDiscrete Third OrderCross Modulation

DistortionsDistortions

Carrier 1Carrier 1 Carrier 2Carrier 2Carrier 1Carrier 1 Carrier 2Carrier 2ActiveActive

Beat Products = Carrier 1 +/- Carrier 2Beat Products = Carrier 1 +/- Carrier 2

Beat Product

Discrete Second Order DistortionsDiscrete Second Order Distortions

55.25 MHz 175.25 MHz

230.50 MHz

229.25 MHz

A+B

121.25 MHz

120.00 MHz

A-B

B

A

CSO Beats in a 77 Channel SystemCSO Beats in a 77 Channel System

50 100 200 300 400 500 550

10

20

30

40

50Subtraction Beats:CSO -F1, -F2, -F3

Addition BeatsCSO +F1, +F2, +F3

Frequency in MHz

NUMBER OF BEATS

60COMPOSITE SECOND ORDER (CSO)COMPOSITE SECOND ORDER (CSO)

• CSO( Single Amp.) = CSO(Spec.) + 2*(Rated Output-Actual Output)

68 + 2*(46 - 48) =

68 + 2*( -2 ) =

68 + -4 =

64 dBc

Beat Product

Beat Product = Carrier 1 +/- Carrier 2 +/- Carrier 3

Discrete Third OrderDiscrete Third Order

ActiveCarrier 1

Carrier 3Carrier 2

Composite Triple Beat DistortionsComposite Triple Beat Distortions

VideoAural

Channel A Un-modulated Carrier

Channel B

Channel A with Cross Modulation from Channel B

Cross ModulationCross Modulation

Multiple Amplifiers

CTB2Amps = 68- 20Log (2)CTB2Amps = 68- 20 x .3CTB2Amps = 62 dBc

This is true if all the amplifiers are identical.CTB is 20 Log because it is a voltage function.

2 Amplifiers

CTB#Amps = CTB1Amp - 20log (#Amps)

Composite Triple Beat Composite Triple Beat

Cross Modulation CalculationCross Modulation Calculation

• XMOD ( Cascade ) = –XMOD ( Single ) - 20Log ( N ) –where N is the number of amplifiers in cascade.

Coaxial Architecture. Tree-and-Branch Architecture Express Trunk.

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