Spac Manual1

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Operating Instructions

SPAC Operating Instructions - Edition 8 - May 2004

BKtel 1570BB

CATV Distribution System

System Performance Analysis

for

CATV Systems

SPAC Release 2.7

Copyright BKtel systems, 2004 - All rights reserved


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SPAC Operating Instructions - Edition 8 May 2004 2

Contents

1 Introduction .......................................................................................................... 4

1.1 This Manual............................................................................................................ 41.2

Important Advice for Using SPAC .......................................................................... 5

1.2.1.... Features ................................................................................................................................ 51.2.2.... Information Required for Calculation .................................................................................... 61.2.3.... New features ......................................................................................................................... 71.2.4.... Interdependencies Registered by SPAC .............................................................................. 81.2.5.... Calculation Accuracy for C/N and CSO/CTB Figures......................................................... 101.2.6.... BER Calculation .................................................................................................................. 111.2.7.... Unmodulated and Modulated AMTV Carriers................................................................... 111.2.8.... Libraries .............................................................................................................................. 121.2.9.... Essential Use of a Load Controlled Amplifier (LCA) ........................................................... 121.2.10 .. Definition of the Modulation Index....................................................................................... 121.2.11 .. Balance Between Optimum C/N and CSO/CTB ................................................................. 15

1.2.12..

Links with Line Extenders ................................................................................................... 15

1.2.13..

Links with Optical Amplifiers ............................................................................................... 16

1.2.14 .. Transmitter Output Levels................................................................................................... 171.2.15 .. Receiver Input Level ........................................................................................................... 17

1.3 Requirements ....................................................................................................... 17

2 Installation .......................................................................................................... 18

2.1 SPAC.................................................................................................................... 182.2 Dongle.................................................................................................................. 19

2.2.1.... Installation of Dongle........................................................................................................... 192.2.2.... Connection of the dongle: ................................................................................................... 20

3 Operation ............................................................................................................ 21

3.1 Getting Started ..................................................................................................... 213.2 New Schematic .................................................................................................... 263.3 Existing Schematic ............................................................................................... 27

4 Main Window of SPAC....................................................................................... 28

4.1 Overview .............................................................................................................. 284.2 Tool Bar................................................................................................................ 294.3 Menu Bar.............................................................................................................. 31

4.3.1.... File....................................................................................................................................... 314.3.2.... Channels ............................................................................................................................. 324.3.3.... Edit ...................................................................................................................................... 33

4.3.4....

Add...................................................................................................................................... 35

4.3.5.... Calculate! ............................................................................................................................ 364.3.6.... Window................................................................................................................................ 364.3.7.... Info ...................................................................................................................................... 374.3.8.... Options ................................................................................................................................ 374.3.9.... IM Simulator ........................................................................................................................ 374.3.10 .. SPQA! ................................................................................................................................. 38

4.4 Status Bar............................................................................................................. 39

5 Edit Module Dialog Boxes ................................................................................. 40

5.1 Source.................................................................................................................. 405.2 Amplifier ............................................................................................................... 42

5.3

Load Controlled Amplifier (LCA)........................................................................... 44

5.4 Optical Transmitter (OTX) .................................................................................... 465.5 Optical Amplifier ................................................................................................... 48


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5.6 Optical loss........................................................................................................... 505.7 Coaxial Loss......................................................................................................... 525.8 Optical Receiver (ORX)........................................................................................ 535.9 Module.................................................................................................................. 56

5.10

Optical Insertion ................................................................................................. 585.11 Coaxial Combiner............................................................................................... 60

5.12 Return Channel Noise........................................................................................ 625.13 Module list.......................................................................................................... 64

6 Procedures.......................................................................................................... 66

6.1 Working with Libraries .......................................................................................... 666.2 Modifying Modules ............................................................................................... 666.3 Creating User Libraries......................................................................................... 676.4 Edit Channel Table............................................................................................... 676.5 Channel List File................................................................................................... 70

7

IM Simulator........................................................................................................ 73

7.1 Using the IM Simulator ......................................................................................... 737.2 IM Calculating Options ......................................................................................... 757.3 Calculation Test.................................................................................................... 767.4 IM Print Options.................................................................................................... 77

8 Menu Control in IM Simulator............................................................................ 78

8.1 x Scaling............................................................................................................... 788.2 y Scaling............................................................................................................... 788.3 Display.................................................................................................................. 78

8.4

Calculate .............................................................................................................. 79

8.5 Test ...................................................................................................................... 798.6 Print...................................................................................................................... 79

9 Console for Monitoring...................................................................................... 79

9.1 Clear..................................................................................................................... 809.2 Buffer.................................................................................................................... 809.3 Position................................................................................................................. 80

10 Appendix............................................................................................................. 81

10.1 Create a Sample Schematic............................................................................... 81

10.2

Warnings and Error Messages........................................................................... 8610.3 List of Abbreviations........................................................................................... 90


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1 Introduction

1.1 This Manual

This instruction manual has been conceived for planning staff whoare familiar with hybrid (optical and coaxial) CATV (CommunityAntenna for Television) systems.

Chapter 1 provides an introduction and important advice for usingSPAC.

Chapter 2 describes the installation of the software SPAC (SystemPerformance Analysis for CATV Systems).

Chapter 3 describes how to start a new schematic and an existingone.

Chapter 4 describes the menu bar, tool bar and status bar of theSPAC main window.

Chapter 5 describes the dialog boxes for editing the modules.

Chapter 6 describes some SPAC procedures.

Chapter 7 describes the IM (Intermodulation) simulator.

Chapter 8 describes the menus of the IM simulator.

Chapter 9 describes the console for monitoring at a specified

frequency.

Chapter 10 is the Appendix and describes a sample schematic.


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1.2 Important Advice for Using SPAC

1.2.1 Features

SPAC is a PCbased simulation tool for evaluating theperformance of CATV distribution networks. The program enablescalculation of the main system parameters carriertonoiseratio

(C/N), the intermodulation products compositesecondorder(CSO) and compositetriplebeat (CTB), as well as the Bit ErrorRate (BER) and Modulation Error Ratio (MER). These parametersdetermine the quality of

- coaxial

- optical (1310/1550 nm)

- mixed (coaxial/optical)

analog CATV transmission systems and their return channels.The input required for simulation of a system is carried outschematically. The schematic modules are entered as simulationmodels from a library, while the CATV source and links (optical orelectrical) are specified by the user. SPAC indicates the systemparameters in two ways:

- In normal calculation mode, they are specified for the individualblocks of the chain at their outputs.

- Alternatively, the contribution for the individual blocks of thechain can be observed.

The SPQA tool is used for the subjective assessment of picturequality.


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1.2.2 Information Required for Calculation

Basically, SPAC has been designed for calculation of thedownstream system performance of the 1570BB system. Sinceanalog AM-TV was the main service, the most important systemperformance parameters were C/N, CSO and CTB. The increasingdemand of calculating the performance of new digital services(such as 64 QAM for downstream digital TV) and various servicesfor the upstream channel (such as polled set top boxes, cablephone and cable modem), made it necessary to develop additionalfeatures for the SPAC. For this reason, the SPAC calculates theBER and MER for digital services. The definition of the servicetype for a specific channel is carried out in the channel list file (e.g.cenelec.lst, upstrm16.lst, ...). The service type must be selectedfor each simulation in order to enable the SPAC to perform thecalculation of the correct system performance parameters (e.g.BER for QAM channels, but not for analog AM-TV and FMchannels).

All schematic modules in the 1570 BB system are stored with theirmain block parameters (gain, noise figures etc.) in the SPAC

libraries. The downstream modules are stored in the 1570_un.dlllibrary, the upstream modules in the upstream.dll library.

In order to calculate the carriertonoise (C/N), theelectrical/optical input levels of the different blocks have to bedefined by linking the blocks with electrical/optical attenuations.

The C/N is calculated in the high frequency (RF) domain. It isnormally expressed to a 5 MHz noise equivalent bandwidth; thefigure, however, can be modified (e.g. to 1 Hz to establish acomparitive figure to the actual service bandwidth, independent of

the channel bandwidth).

The second and third order nonlinearity determines the entiretransmission path quality in terms of nonlinear distortions, as longas the optical transmitters are not overloaded (overmodulated). Itis therefore sufficient to calculate the CSO and CTB contributionper transmission path block. Apart from the 1310/1550 nmtransmitters, all blocks (electrical/optical amplifiers and opticalreceivers) operate well below their saturation point as long assuitable output levels are used (default values of the blocks in thelibraries).

To carry out the CSO/CTB calculations, the channel allocationmust be selected first because the nonlinearity of the blocks, and


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thus for the complete transmission system, is a function of thenumber of transmitted (TV) channels, their frequency range andtheir spacing. The SPAC calculates the number of intermodulationbeats per frequency cycle as a function of the channel allocation in

the first run.

During the second run, the number of intermodulation beats iscombined with the individual block nonlinearity (per IM beats).The total nonlinearity per block is calculated in accordance withthe specially defined channel allocation. After this is completed,the result is added to that of the block before the completetransmission path chain is calculated.

1.2.3 New features

SPAC 2.7 adds several new features to the release SPAC 2.6:

Support of QAM128, QAM32 and QAM8 upstream services.

Support of the new OTXD module with additional features:adjustable output power and Fiber Length Compensation.

Support of the new OAH module with additional feature:adjustable output power.

Finetuned calculation of fiber effects in operation with OTX.


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1.2.4 Interdependencies Registered by SPAC

1.2.4.1 Optical Transmitters

The SPAC knows the amount of CSO/CTB to be created in opticaltransmitters for an optimum channel modulation index when thechannel allocation is defined. The SPAC normally accomplishesthis automatically. The SPAC sets the channel modulation index toa value where the clipping influence on the CATV signals can beneglected (about 44% related to modulated carriers and 26% to

unmodulated carriers). The total modulation index is determinedby SPAC multiplying the channel modulation index by the squareroot of the effective channel load. Afterwards, SPAC calculates theC/N of the transmitter (it is mainly a function of the channelmodulation index and the transmitter RIN). The SPAC handlestransmitter clipping effects.

1.2.4.2 Optical Amplifiers

Optical amplifiers have a negligible CSO/CTB contribution. In spite

of this, SPAC adds the CSO/CTB of optical amplifiers to theCSO/CTB of the transmission chain. The noise figure of the opticalamplifier is a function of the input level. This interdependency isstored in the libraries for the different optical amplifiers. The C/Ncontribution can be calculated when the input light level is stated.


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1.2.4.3 Fiber

Fiber effects arising in long optical feeders, such as fiber intensitynoise resulting from to Rayleigh BackScattering (RBS) or PM/AMconversion caused by fiber chromatic dispersion, SBS (StimulatedBrillouin Scattering), and SPM (SelfPhase Modulation) are partlyconsidered. The dynamic of RBS and PM/AM induced fiberintensity noise is taken into account by the SPAC, the SBSthreshold is integrated as a limit value, according to the opticaltransmitter and fiber length. The effects caused by SPM are alsoincluded. However, due to the very complex nature of SPM and

CSO compensation effects, a high degree of accuracy is notalways achieved. In practice, the CSO rises very quickly if acertain fiber length is exceeded. In this case, a difference of only afew kilometers influences the CSO considerably and sometimesrender the accuracy of the calculation relatively low.

1.2.4.4 Optical Receivers

The CSO/CTB is calculated as a function of the optical input lightand electrical output power. C/N is determined by the light and

RMS noise received (stored in the library). The SPAC can handlepreemphased receiver outputs, too.

1.2.4.5 Coaxial Amplifiers

The SPAC requires the input levels and channel allocations for thecoaxial amplifiers. The C/N can be estimated from the noisefigures already stored and the CSO/CTB is calculated from thechannel allocation and output level. The frequency dependency ofthe CSO/CTB of hybrid amplifiers is similar to SPAC. Flat and pre

emphased output levels can be created and are taken into accountwhen calculating CSO/CTB. The frequency reference point is 862MHz.

1.2.4.6 General prerequisites

- The output power levels of the optical amplifiers do not exceed17 dBm.

- BKtel 1570BB default transmitters are used.

- All optical return losses are lower than 50 dB.

- All electrical return losses are lower than 16 dB.


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1.2.5 Calculation Accuracy for C/N and CSO/CTB Figures

1.2.5.1 Influence of the Frequency Response on the System Parameters

Apart from the preemphased outputs of the optical receivers andcoaxial amplifiers, SPAC has no information on frequencyresponses. Therefore, it assumes an ideal flat frequency responsewithout any ripples. The C/N, CSO and CTB figures are referred tonominal (mean) carrier amplitudes.

If a carrier is down (e.g. 1 dB related to the nominal value) all threetransmission parameters are normally reduced by 1 dB and viceversa. The more electrical interfaces are added to the

transmission chain, the more frequency response is added and themore the C/N, CSO and CTB figures will differ in the individualchannels compared to the calculated nominal value.

Assuming a rippleless, steadily frequency response, the accuracyof C/N calculations normally achieve 1 dB and CSO/CTBcalculations 2 dB. The frequency response deviations must beadded to this tolerances (see above). This fact has to be taken intoaccount when defining a system: Expert customers often requirethe guaranteed system parameters for the worst case (minimumlevel) carriers.

1.2.5.2 Addition Rules Used for SPAC Simulations

For calculations between the transmission blocks, SPAC uses:

- 10 log for C/N additions,

- 12 log for the CSO addition,

- 15 log for the CTB addition.

The 12 log and 15 log can be changed in Expert Mode.

The phase relationship between the individual transmission blocksis never constant with regard to the number of blocks and theindividual transmission frequencies. Therefore, the 12 log rule forCSO and the 15 log rule for CTB are only considered statisticalrules. It was mainly derived from extensive measurements,particularly of HFC systems.

The individual IM beats within the transmission blocks themselves

cannot be changed. SPAC applies for block internal nonlinearitycalculations:

- 7 log for the CSO addition,


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- 8 log for the CTB addition.

1.2.6 BER Calculation

Today, many of the services offered by an HFC platform aredigital. The type of service considered for calculation must beselected for each simulation. If a digital modulated carrier isselected, SPAC calculates the BER from the CNR and also acorrection factor, which accounts for some CSO and CTB.However, the CSO and CTB contribution to the BER has not beenwidely verified to date. The contributions of QAM AM-TV andQAMQAM intermodulation to C/N is not considered.

1.2.7 Unmodulated and Modulated AMTV Carriers

The system parameters CSO/CTB and C/N can be defined toeither unmodulated AM-TV carriers or modulated AM-TV carriers.In the case of unmodulated carriers, the carrier peak amplitude isapprox. 4.5 dB lower than that of the peak amplitude of themodulated carriers if an LCA is used and the channel load onlyconsists of AMTV carriers. (If there are also FM and digitalchannels, such as QAM, that have the same signal power at thesystem input independent of the modulated or unmodulated AM-

TV carriers, the difference between the AM-TV peak levelsdownstream from the LCA are somewhat lower than 4.5 dB sincethe summation load difference is lower in this case. The SPAC isnow also capable of taking these effects into account properly).

The intermodulation and noise floor are always measured asaverage values. Therefore, when using modulated carriers, theC/N, CSO and CTB ratios differ about 4.5 dB to the modulatedcase. The SPAC calculates the difference between the modulatedand unmodulated channel load in the summation load. It then

readjusts the peak carrier levels of the LCA and the followingmodules correspondingly. If a pilot controlled optical receiver oramplifier is used somewhere in the transmission chain followingthe LCA, there is no readjustment of the peak carrier amplitude.Please note that the CSO and CTB contributions also change forthese modules but there is no change in the C/N contribution if themodulation of the AM-TV carriers is switched on. The SPAC thencalculates the correct peak output level as well as the correct C/N,CSO and CTB contributions in all of these cases.


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1.2.8 Libraries

The system parameters CSO/CTB and C/N can be defined to

either unmodulated carriers or modulated carriers. In the case ofunmodulated carriers, the carrier amplitude is about 4 ... 5 dBless than that of the peak amplitude of the modulated carriers. Theintermodulation and noise floor are always measured as averagevalues. Therefore, when using modulated carriers, the C/N,CSO/CTB ratios are about 4.5 dB lower than those when using themodulated case. By applying this rule of thumb, it would not benecessary to use two libraries. However, the Load ControlledAmplifier (LCA) changes the system parameters as a result of the4.5 dB level shift, which is different to a constant gain amplifier.Also, pilot controlled receivers behave differently at the systemoutput in comparison to nonpilot controlled receivers. Therefore,the system parameter calculations between modulated andunmodulated carriers are more complex and, thus, two individuallibraries are necessary.

1.2.9 Essential Use of a Load Controlled Amplifier (LCA)

NOTICE

It is necessary to use a Load Controlled Amplifier (LCA) in frontof most optical transmitter because the transmitter library module

assumes one is present.If not, the results received are not correct. SPAC warns you if thetransmitter needs an LCA and you have forgotten it.

The LCA permanently keeps the optical transmitter in its optimumcondition in terms of channel modulation index and the number ofchannels. The system is modulated as high as possible thusachieving a high degree of costeffectiveness. The LCA outputlevel and, thus, the transmitter channel modulation index should

only be corrected by experienced users. If the transmitterCSO/CTB contribution is too high, it must be reduced. A manualincrease of the channel modulation index should be avoided in allcases, even by expert users.

1.2.10 Definition of the Modulation Index

The total modulation index is about SQR(N) times the figure of thechannel modulation index. This is valid for both unmodulated and

modulated carriers. However, when using modulated carriers, thepeak amplitude is about 4.5 dB higher in comparison to the meanvalue or unmodulated carriers. Therefore, the total modulationindex is also 4.5 dB higher when compared to unmodulated


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carriers (44% in the modulated case compared to approx. 26% inthe unmodulated case).

The LCA keeps the total channel load constant. Therefore, in case

of modulated carriers, the peak level of a TV channel is about 4.5dB higher in comparison to the unmodulated level or the meanvalue of the modulated channel. This is valid for all BKtel 1570BBunits which are cascaded following the LCA.

However, a pilot controlled receiver, such as the CRX-LD,compensates for this effect on the receiver side.

This 4 to 5 dB difference is currently being examined for PAL-Band SECAM; in the case of PAL-M the difference could be 1 dBlower. In the case of an OPAL 94 channel allocation with 62

effective PAL-B AM-TV channels, the channel modulation indexwould be about 5.5% for modulated carriers and 3.8% forunmodulated carriers.

It must be taken into account that, in practice, the total modulationindex may not be different for modulated and unmodulatedcarriers. The LCA always controls this total channel load to thesame effective power at its output. But, when defining the channelmodulation index to the peak level of the carrier (e.g. the sync.pulse level in case of PAL-B modulation), the channel modulation

index is 4.5 dB higher in comparison to the unmodulatedsinusoidal carrier. Therefore, if the above mentioned square root(N) law for the total modulation index should be valid formodulated and unmodulated carriers, the total modulation index isalso 4.5 dB higher compared to unmodulated carriers when usingmodulated carriers.

SPAC users can select between both conditions. They should takeinto account that the real TV picture behaves in the same way asthe modulated carrier condition, but unmodulated carrierconditions are preferred for a lot of CATV system definitions

carried out by customers and CATV specialists for measurementand definition purposes (e.g. CENELEC).

The influence of the LCA regulation, however, usually requires anexplanation being given to the customer. The planning engineermust explain what will happen when switching an unmodulatedchannel allocation to the modulated condition: The peak amplitudeof the modulated carrier is increased by about 4.5 dB and also,therefore, the carrier amplitude at the output of the system when itis not compensated for by the use of a pilot controlled receiver.

The influence of the system parameters C/N, CSO and CTB, whenswitching from unmodulated to modulated carriers, can easily be


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shown by the planning engineer using SPAC because he canswitch between the two conditions.

The result is that the planned C/N target can only usually be

achieved at an attractive price by using the modulated case. Theintermodulation ratio normally must be defined to the unmodulatedcarrier condition (necessitated by a customer requirement). Thesystem output level is approx. 4.5 dB less in comparison to asystem which is not LCA controlled, thus providing animprovement in CSO/CTB behavior (valid as long as no pilotcontrolled receiver is used). This must normally be explained indetail and seriously to the customer to convince him thatBKtel 1570BB equipment provides an optimum balance betweenadvantageous system parameters on the one hand and anattractive price on the other.

NOTICE

The 4.5 dB offset between the unmodulated and the modulatedcase is only a rule of thumb. If there are other services, such asQAM and FM, this offset decreases according to the ratio ofsignal powerof the AMTV channels and the other channels.

When the number of channels is increased (usually at a later datewhen the system is already sold and in service), the channelmodulation index is reduced corresponding to the SQR(N) law ifthe number of channels is higher than 40 and vice versa. Below 40channels (assuming a nominal input level of 79 dBV) themaximum gain of the LCA is achieved and the channel modulationindex remains constant. This behavior is fully reflected in theSPAC tool. The planning engineer must request the maximumnumber of TV channels which are planned to be transmitted withthe BKtel 1570BB system in future in order to plan using thecorresponding channel modulation index. Otherwise, the systemparameters cannot be fulfilled when the number of channels is

increased after subsequently being put into service.


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1.2.11 Balance Between Optimum C/N and CSO/CTB

The channel modulation index is the common parameter: thehigher it is, the better the C/N and the worse the CSO/CTB for aspecific channel load and receiver output level. Since the opticalamplifiers contribute almost nothing to the CSO/CTB, it ispreferable to define a pointtopoint link with SPAC first of allusing only one EPA, one LCA, one OTX and one optical receiver.Then define the channel allocation and receiver output level whichneeds to be achieved.

NOTICE

The output level of the optical receiver is defined at 862 MHz.

By using this quick exercise, it soon becomes apparent if thedefault figures in the library will enable the required CSO/CTBsystem figures to be achieved. If this is not the case, and neitherthe number of TV channels nor the receiver output level can bereduced, the only possibility is to reduce the OTX channelmodulation index by reducing the LCA output level by using the

SPAC Expert Mode.

This helps to solve the problem if a significant amount ofCSO/CTB (>50 %) is contributed by the optical transmitter. If theoptical receiver contributes the greater share of intermodulation,the receiver output level for the specific channel load is too high.

When the channel modulation index has been optimized, theoptical amplifier chain can be embedded in the right way in orderto cover the optical budget in conjunction with the required C/N.

1.2.12 Links with Line Extenders

If the link includes Line Extenders, they should be included fromthe beginning to determine their contribution in terms ofintermodulation. An attempt should be made to achieve minimumdegradation in intermodulation and C/N contribution through themby selecting the correct electrical input level and line extendergain. Generally, this is easier the smaller the gain selected.However, the smaller the gain, the smaller the coaxial link budget.Trial and error must be used on the SPAC to find a suitablecompromise.


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An optimized cascade of two Line Extenders should not degradethe CSO/CTB more than 2 or 3 dB in comparison to the figure atthe output of the optical receiver. Their C/N degradation should beless than 0.5 dB. If the total required CSO/CTB for the complete

link (fiber optic plus line extender cascade) cannot be achieved,and the Line Extender CSO/CTB degradation is higher than thatmentioned above, do not attempt to correct the fiber optic part byreducing the channel modulation index of the optical transmitter orthe optical receiver output level.

If the optical receiver CSO/CTB is dominant within thetransmission chain, it is useful to reduce the receiver output leveland increase the gain of the following Line Extender in order tocover the same coaxial budget.

1.2.13 Links with Optical Amplifiers

It is recommended to retain the minimum input level for the opticalamplifiers, otherwise the simulation is interrupted.

Take the different minimum input levels for the different OAAs intoconsideration:

Optical Amplifier Min. input level

Optical Amplifiers of OAAS family:

OAAS815SA (1 output, +16 dBm)

OAAS815DA (2 outputs, +13 dBm)

-4 dBm

Optical Amplifiers of new OAH family:

OAHnppd

-4 dBm

Optical Amplifiers of OAH family:

OAH0216B (2 outputs, +16 dBm)

OAH0316A (3 outputs, +16 dBm)



OAH0613A (6 outputs, +13 dBm)


-2 dBm


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1.2.14 Transmitter Output Levels

The directly modulated 1310 nm transmitters provide either +8dBm or +11 dBm.

The new directly modulated OTX family has adjustable outputlevels.

The external modulated transmitter OTXE090 provides 2 outputs,each with +7 dBm.

1.2.15 Receiver Input Level

Strictly seen, the minimum receiver CW level is a function of thechannel modulation index. In the case of normal channel loads(higher than 40 AM TV channels), it must be higher than -8 dBm inorder to provide a useful C/N at its output. It should not exceed +2dBm at the receiver input to prevent receiver overloading (evenwhen high C/N ratios are required). Also consider the fact thatmost receivers have two input dynamic ranges (-7 dBm to +1 dBmand -4 to +4 dBm, related to m=5%).

Planning should be performed in this way to allow a margin for theCW regulation range limit of the receivers because there may betolerances in the optical pointtomultipoint budgets.

1.3 Requirements

SPAC runs under MSWindows 3.1 or higher. In order to use theSPQA tool for subjective assessment of picture quality, a VGA

adapter with a color resolution of at least 16,777,216 colors isnecessary (true color resolution 24 or 32 bit) .

The user must be familiar with the basic features of MicrosoftWindows.


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2 Installation

2.1 SPAC

This version is equipped with a setup routine. To run the SPAC,install the program as described below:

1. Run MSWindows 3.1 or higher.

2. Installation of SPAC by CD:Insert the original SPAC CD. Display the directory \ ofthe CD drive with your file manager. Run Setup.EXEby double clicking the file name in the file manager.Follow the installation procedure. The default installationdirectory is C:\ProgramFiles\BKtel\spac but can bechanged during the installation process.

3. Start SPAC by double clicking on the icon created on

the desktop or by double clicking on SPAC.EXE in theFile Manager/Explorer.


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2.2 Dongle

BKtel ships SPAC with two different types of dongles: for parallelinterface or for USB.

2.2.1 Installation of Dongle

Please start the appropriate file to install the dongle driver.It is located on the SPAC CD in the directory \dongle.

The dongle driver is the same for parallel and for USB dongle.

Drivers:- hldrv16.exe Driver for Windows 3.1

- hldrv32.exe Driver for Windows 95/98, Win2000, Win ME, WinNT and Win XP.

NOTICE

You need system administrator rights for Win NT and WinXP

Display the directory \dongle of the CD drive with your filemanager. Double click on the appropriate driver file to execute thedongle driver software installation program given in the Readmefile.Example: Double click on D:\dongle\hldrv32.exe to start theHardlock device driver installation program Hldrv32.exe forWinXP.


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Figure 1 Hardlock Device Driver Installation Program (Example)

To unlock the SPAC applications first install the device driver asdescribed above before you connect the dongle.

NOTICE

It is not necessary to change the SYSTEM.INI. The driver will beloaded automatically.

2.2.2 Connection of the dongle:

- Connect the dongle to the parallel port or the USB port of thePC.

- If the dongle is not connected to the PC or the driver is notinstalled an error message occurs when starting the SPACsoftware.


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3 Operation

3.1 Getting Started

Start SPAC by double clicking on SPAC.EXE in the FileManager, or on the icon in the Program Manager.

The following message appears:

Figure 2 About SPAC

Click on OK and then start your planning session.The Read Channel List menu opens to select a channel list.


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Figure 3 Read Channel List

The following channel lists are available:

Channel List Downstream/Upstream

Note

BK2000 Downstream Channel allocation of BK Upgrade for KDG Germany

BK256QAM Downstream 40 256QAM channels

CENELEC Downstream Test channel allocation of 42 TV carriers defined byCENELEC standardization group

EUROPE Downstream Test channel allocation applicable to European cable

operators

NTSC77 Downstream Test channel allocation of 77 TV carriers and 30 FM

carriers defined by the NTSC standardization group


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Note

NTSC110 Downstream Test channel allocation of 110 TV carriers and 30 FM

carriers defined by the NTSC standardization group

NTSC129 Downstream Test channel allocation of 129 TV carriers applicable to US

cable operators

U04X16QM Upstream 4 16QAM channels, 1 FSK (LES / SET Top Box)

U04XQPSK Upstream 4 QPSK channels, 1 FSK (LES / SET Top Box)





U20X16Q2 Upstream 20 16QAM channels, DVB Cable Modem System (2MHz

bandwidth), 1 FSK (LES / SET Top Box)


bandwidth), 2 FSK (LES, SET Top Box)





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Note



Table 1 Read Channel List Items

Select an item from the channel list and click on OK.

NOTICE

SPAC remembers the channel list of a previous session. If youopen SPAC for the next session, the main screen opensimmediately.


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The main screen of SPAC opens.

Figure 4 Main Window of SPAC

The SPAC window has a menu bar and tool bar at the top and astatus bar at the bottom.

To create or load several schematics into the main window, openthe File menu via the menu bar and select New or Open.


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3.2 New Schematic

To create a new schematic, open the File menu in the menu barand select New. The following window appears:

Figure 5 Creation of a New Schematic

NOTICE

The Schematic window contains a title window to entercomments concerning a calculation. The Schematic window alsodisplays the modules representing the components (opticaltransmitters, amplifiers, etc.) selected for the calculation.

Commands concerning a schematic can be executed via the FileMenu. Use the Add menu to add modules to the schematic. Usethe Edit menu to change modules.


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A CATV system typically has modules in the following order:

- Coaxial (cascaded) Amplifiers (AMP) which may be Equalizer

Preamplifiers (EPA), Load Controlled Amplifiers (LCA) or anyother coaxial amplifiers, an optical transmitter (OTX), a mixtureof (i.e. cascaded optical amplifiers and fiber line)

optical loss which may be a fiber line, a splitter, acombination of both or a tap

an optical analog amplifier (OAA)

optical loss which may be a fiber line, a splitter orboth

-

- an optical receiver (ORX), coaxial loss related to the accessnetwork or line extenders.

Select the modules in the order in which the system is to beplanned.

3.3 Existing Schematic

To load an existing schematic in the library, open the File menuin the menu bar and select Open.

Figure 7 Load an existing Schematic


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4 Main Window of SPAC

4.1 Overview

A calculation is always carried out for a specific service which canbe selected via the Channels Menu. A calculation isautomatically performed by the SPAC after changing module data,changing the active library or selecting the command Calculate!.

CSO, CTB and MER calculation is only possible when the IMsimulator is activated.

Readonly libraries or individual modules can be created in userlibraries to carry out calculations.

When a new schematic is opened, SPAC automatically loads thedefault source module. The default source module determines theactual library. Change the default source by saving a sourcemodule to the SPAC directory. Also refer to Edit Source.

To carry out a subjective picture quality assessment, run theSPQA tool by selecting SPQA! from the main menu.

The Options menu enables switching to Expert mode andexecuting other functions.

For more information, refer to:

- Working with Libraries

- Modifying Modules- Creating User Libraries

- Using the IM Simulator

- Subjective Picture Quality Assessment


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4.2 Tool Bar

The tool bar at the top of the SPAC window provides somecommands from the File, Add and Edit menus:

File: New.

File: Open.

File: Save As.

File: Print Overview.

A list box for displaying and selecting the

active library.

CNRBw: 4.00 MHz

A text field for displaying either the

bandwidth to which all CNR values are

related to or a warning if the calculated

data is not updated.

Cut Module.

Add: ORX (Optical Receiver).

Add: OAA (Optical Analog Amplifier).

Add: OTX (Optical Transmitter).

Add: AMP (Electrical Signal

Amplifier).


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Add: LCA (Load Controlled Amplifier,

electrical).

Add: OptLoss (Splitter or Fiber).

Add: OptInsert

Add: CoaxLoss (Coaxial Line).

Add: Combiner

Add: RCNoise

Add: Modul list

Table 2 Tool Bar


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4.3 Menu Bar

4.3.1 File

The system to be simulated is entered as a schematic. Severalschematics can be displayed at a time. The File menu includes thefollowing commands with which to manipulate the schematics:

Starts a new schematic.

Loads a schematic from disk.

Activates the title window of the active schematic. If a mouse isconnected, simply click in the title window. This window can beused to enter comments which are subsequently printed out whenprinting the calculated schematic.

Selects a library with a channel allocation. If a mouse isconnected, simply click on the list box in the tool bar.

Saves the active schematic to disk.

Prints out the active schematic as a short overview, correspondingto the display.

Prints the active schematic in detail.

Configures the printer.

Closes the active schematic.

Exits the program.

Loads the schematic last used from disk.filename represents the file name of the schematic.

New

Open...

Title...

Library...

Save, Save As...

Print Overview

Print Details

Print Setup...

Close

Exit

filename.SCM


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4.3.2 Channels

This command selects a channel list file.

This command calls in the Edit Channel Table dialog.

The services VSB-AM, FM, 256 QAM, 64 QAM, 16 QAM, DQPSK,QPSK, FSK, PSK are available.

This command calls in an editor to edit a channel list file. As

default, the Windows Notepad is called. A different editor can beused by adding the corresponding entry in the SPAC.INI file in thewindows directory. (First of all, add a [moddy] section and thenadd the line editor=myeditor.exe).

Select this item so that the channel list last used is called in atstartup.

Read Channel List

Edit Channel Table

Service

Edit Channel List

Always use lastchannel list atstartup


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4.3.3 Edit

The Edit menu contains commands that enable modules to bedeleted and to change and view module parameters.

Deletes a module from the schematic. This can also be executedby the key combination + .

NOTICE

If Expert mode is not active or a library model is being edited, notall parameters can be changed. Modules which cannot be editedare indicated by the magnifier cursor. Modules which can beedited are indicated by the screwdriver cursor.

Edits module data of the selected module. This can also beactivated by double clicking with the left mouse button on themodule or pressing the key. For detailed information,refer to Chapter 5.

Each module has a specific editing dialog box. These are listedbelow:

- Source edits the CATV source.

- Amplifier edits a coaxial amplifier.

- Load Controlled Amplifier edits a load controlled amplifier.

- Optical Transmitter edits an optical transmitter.

- Optical Amplifier edits an optical amplifier.

- Optical Loss edits an optical link (splitter, line or tap).

- Coaxial Loss edits an electrical link.

- Optical Receiver edits an optical receiver.

- Module edits a module with fixed contributions.

- Optical Insertion edits an optical insertion module.

- Coaxial Combiner edits a coaxial combiner.

- RCNoise edits a return channel noise module.

- Module list edits a list of two combined modules.

Cut module

Edit module


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NOTICE

The following command is only available for AMP, LCA, OTX,OAA and ORX modules.

Displays the contribution data of the selected module. Thecontribution data can be shown with the menu command, pressingthe key or by clicking on the module with the right mousebutton.

Show contributationdata


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4.3.4 Add

The Add menu can be used to add modules from a library to theschematic. Figure 8 illustrates a module from the library.

Figure 8 Coaxial Loss Module in a Schematic

Adds an OTX (optical transmitter) from a library to the schematic.This command is also available as a button in the tool bar.

Adds an OAA (optical amplifier) from a library to the schematic.

This command is also available as a button in the tool bar.

Adds an ORX (optical receiver) from a library to the schematic.This command is also available as a button in the tool bar.

Adds an AMP (coaxial amplifier) from a library to the schematic.This command is also available as a button in the tool bar.

Adds an LCA (load controlled amplifier) from a library to theschematic. This command is also available as a button in the toolbar.

Adds an optical link or loss into the schematic. This command isalso available as a button in the tool bar.

Adds an optical insertion to the schematic. This command is alsoavailable as a button in the tool bar.

Adds a coaxial link or loss to the schematic. This command is alsoavailable as a button in the tool bar.

Adds a coaxial combiner to the schematic. This command is alsoavailable as a button in the tool bar.

OTX ...

OAA ...

ORX ...

AMP ...

LCA ...

OptLoss

OptInser

CoaxLoss ...

Combiner


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Adds a RCNoise (return channel noise) module to the schematic.This command is also available in the tool bar.

Adds a module with contributions which the user can individually

define to the schematic.

Adds a module list which consists of two combined modules.

Creates a user defined module (only available in Expert mode).Use the command sequence Create module" Load..." to loadany user defined module from disk.

4.3.5 Calculate!

Calculates the active schematic.

4.3.6 Window

This menu is for titling, cascading, arranging, closing and selectingthe schematic windows.

Displays the open schematics in columns.

Displays the open schematics overlapping each other.

Places the schematic icons at the bottom left of the main SPACwindow.

Closes all open schematic files.

Displays the names of the opened schematics.

RCNoice

MODULE

ModuleList

Create module

Title

Cascade

Arrange Icons

Close All


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4.3.7 Info

Displays information concerning SPAC and is symbolized by agraphical symbol which appears beneath.

4.3.8 Options

This option can be used to select the title and module font for theschematics. The font is also used in the print out.

This option can be used to select the number of columns used inthe schematics.

This option can be used to toggle between Expert mode andNormal mode.

This option can be used to vary the size of the tool bar and status

bar.

This option can be used to load any bitmap file from the disk to thebackground of the SPAC window.

4.3.9 IM Simulator

This menu item can be used to enable and disable the IMsimulator (Intermodulation simulator).

Fonts

Schematic

Expert Mode

Bar Sizes

Picture


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4.3.10 SPQA!

Select this menu to run the SPQA tool. A subjective picture qualityassessment appears (see Figure ).

Figure 9 SPQA Picture

In order to run the SPQA! simulation, select modulated carriers

from the Edit Channel Table window (see Chapter 6.4).


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4.4 Status Bar

The status bar at the bottom of the SPAC window displays theselected service, current channel allocation, presence ofmodulated AM carriers, a short help text and, if used, the versionof the selected readonly library (see Figure ).

Figure 10 Statusbar


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5 Edit Module Dialog Boxes

To edit module data, click twice on a selected module or carry outthe following steps to call in the module dialog boxes described inthe following chapters:

1 Select the module in a schematic to be edited.

2 Select Edit Module from the SPAC Edit menu. The

corresponding dialog box opens.

5.1 Source

Figure 11 Edit Source Dialog Box

The Source module represents the upstream or downstreamsource of the CATV.


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Use the Load and Save buttons to load or save the SOURCEmodule from or to the disk respectively. Use OK to terminateediting. Use the Cancel button to terminate editing withoutaffecting any changes to the module. The default values for the

source are changed if the module is saved in the SPAC directory.The SOURCE module is specified with the following parameters.None of the parameters are servicerelated, meaning they arerelated to the nonlowered carrier level.

The name of the source can be freely defined.

The CNR, CSO and CTB of the source.

The output level of the source.

The equivalent channel number of the source. This parameter iscompleted during simulation and cannot be edited.

This function determines how SPAC adds IM contributions of thecascaded modules. The value can only be changed in Expertmode if no library has been selected.

The bandwidth to which all CNR values in the schematic arerelated to.

The service or channel bandwidth.

The IM" button opens the dialog box Parameter for IM simulation(refer to Figure 26).

source name

contributions

output level

equivalent channels

rules

CNR bandwidth

Service bandwidth


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This module defines the CSO CTB and CNR of the CATV signal atthe beginning of the transmission system. It also defines thechannel number when no IM simulator is active.

5.2 Amplifier

Figure 12 Amplifier Dialog Box

Use the Load and Save buttons to load or save the coaxial

amplifier module from or to disk, respectively. Use OK toterminate editing. Use the Cancel button to terminate editingwithout affecting any changes to the module. The AMP module is

Simulation behavior


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specified with the parameters listed below, which can only bechanged in Expert mode when no library is active. None of theparameters are servicerelated, meaning they are related to thenonlowered carrier level.

The name of the amplifier can be freely defined.

Indicates the noise figure dependency on the optical input power.

The preemphasis in dB for the frequency span from 47 to 862MHz.


Indicates the CSO and CTB contributions in dB at a referenceoutput level. These values are the maximum values in thefrequency range of the selected service. Ensure that CSO or CTBbeats are present between the band limits when changing thesevalues in order to prevent undefined behavior of the simulationmodel.

Indicates the saturation effects 2ndand 3rd order.

The module calculates its CSO, CTB and CNR contributionsdependent on the input signal and channel allocation.

amp name

noise figure

preemphasis

contributions

saturation effects

Simulation behavior


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5.3 Load Controlled Amplifier (LCA)

Figure 13 LCA Dialog Box

The Load Controlled Amplifier keeps the total modulation index of

the following optical transmitter constant when changing the inputpower or the equivalent channel number. This is achieved bycontrolling the total load.

Use the Load and Save buttons to load or save the LCAmodule from or to disk, respectively. Use OK to terminate editing.Use the Cancel button to terminate editing without affecting anychanges to the module.

The LCA module is specified with the parameters listed below,which can only be changed in Expert mode when no library is

active. When editing a library model, only the total load can bechanged. None of the parameters are servicerelated, meaningthey are related to the nonlowered carrier level.


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The name of the Load Controlled Amplifier can be freely defined.

The electrical output of the LCA. The output can be changedindirectly by adjusting the total load. This value can be fine tunedby pressing the key.

The total modulation index is determined by the following OTX.

The noise figure of the LCA.

Indicates the maximum gain of the LCA if the max. gain isreached. The SPAC issues a warning to the user and calculatesthe output level with the max. gain.

Indicates the CSO and CTB contributions in dB at a referenceoutput level. These values are the maximum values in thefrequency range of the selected service. Ensure that the CSO orCTB beats are present between these band limits when changingthese values in order to prevent undefined behavior of thesimulation model.

The module calculates its CSO, CTB and CNR contributionsdependent on the input signal and channel allocation. The outputlevel is dependent on the total channel load.


LCA name

output

total mod. index

noise figure

gain

contributions

Simulation behavior


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5.4 Optical Transmitter (OTX)

Figure 14 Optical Transmitter Dialog Box

Use the Load and Save buttons to load or save the OTXmodule from or to disk, respectively. Use OK button to terminateediting. Use the Cancel button to terminate editing withoutaffecting any changes. The OTX module is specified with theparameters listed below, which can only be changed in Expertmode when no library is active. None of the parameters areservicerelated, meaning they are related to the nonloweredcarrier level.

The name of the Optical Transmitter can be freely defined.otx name


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Indicates the channel modulation index of the laser. This index isalso calculated by the SPAC from the input level for the OTX anda multiplication factor. Changing the channel modulation index, infact, changes the multiplication factor. This value can be fine

tuned by pressing the key.

This check box determines a mandatory LCA located in front.

The OTX is defined by its maximum total modulation index forlaser clipping; the total modulation index is calculated from theequivalent channel number and the channel modulation index.There are two limit values: limit1 is used at channel numbers >16,limit 2 below or equal to 16 channels. This is due to differentcalculation methods at high and low channel numbers. If one ofthe limit values is set to 0, the other limit with the corresponding

calculation method is always used.

The module output is defined by its optical wavelength and outputpower. Some OTX types have adjustable output power. It can bespecified if there is an isolator or not. If an isolator is missing therewill be additional bit errors due to impulse noise. The Fiber LengthCompensation is available for some OTX types. The OTX may beoptimised with this value to compensate fiber distortion effects.

Indicates the Relative Intensity Noise (RIN) of the laser. The chirp

parameter describes the chirp characteristic of the opticaltransmitter.

The input attenuator adds a variable or fix loss to the electricalinput.

Indicates the clipping value kclip. SPAC uses a clipping value fora better precised calculation of the MER degradation.

Indicates the CNRO and CTB contributions at a reference channelmodulation index. These values are the maximum values in the

frequency range of the selected service. Ensure that the CSO orCTB beats are present between these band limits when changingthese values in order to prevent undefined behavior of thesimulation model.

The Int" button opens the dialog box for internal OTX parameters.


The LHS" button opens the dialog box Parameter for long haulsimulation.

mod. index

needs LCA

total modulation

output

laser

input attenuator

clipping

contributions


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5.5 Optical Amplifier

Figure 15 Optical Amplifier Dialog Box

Use the Load and Save buttons to load or save the OAAmodule from or to disk, respectively. Use OK to terminate editing.Use the Cancel button to terminate editing without affecting anychanges. The OAA module is defined by the parameters listedbelow, which can only be changed in Expert mode when no library

is active. None of the parameters are servicerelated, meaningthey are related to the nonlowered carrier level.

Simulation behavior


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The name of the Optical Analog Amplifier can be freely defined.

Indicates the optical output level. This is adjustable for some OAAtypes.

Indicates the minimum input level (for valid module parameters).

Indicates the noise figure dependency on the optical input power.

Indicates the optical window in which the simulation model is valid.

Indicates the CSO and CTB contributions at a reference channelmodulation index. These values are the maximum values in thefrequency range of the selected service. Ensure that the CSO orCTB beats are present between these band limits when changingthe values in order to prevent undefined behavior of the simulationmodel.



oaa name

output level

input level

noise figure

optical window

contributions

Simulation behavior


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5.6 Optical loss

Figure 16 Optical Loss Dialog Box

Use the Load and Save buttons to load or save the OptLossmodule from or to disk, respectively. Use OK to terminatesediting. Use the Cancel button to terminate editing withoutaffecting any changes. The OptLoss module is defined by the

following parameters:


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The name of your Optical Loss can be freely defined.

Selcts the type of the optloss module. Possible types are tap, X-splitter (OSCM) or a regular splitter (OSC/ODF). The last one maybe combined with a connected fiber of configurable length. For apure fiber without any splitter choose the splitter value 1:1.

Indicates the fiber length in km and the fiber attenuation in db/km.

Select a splitter: 1:1 for none, 1:2, 1:3, 1:4, 1:8, 1:16, 1:32. Thesesplitters have predefined attenuations. To use other values, definethem with add.loss.

Indicates the number of connectors and the connector attenuation.

Indicates the additional loss in dB.

Indicates the position of the fiber. This is relevant for SBS.

Selects a tap type: 4, 5, 6, 7, 8, 9, 10 or 12 dB attenuation. Thesetaps have predefined attenuations. To use other values, definethem with add.loss.

Selects the used output of the tap: tap output or insertion output.This influences the tap attenuation of the optical line.

The SPM" button opens the dialog box Parameters for SPMsimulation.

This module reduces the optical power level by its insertion loss.Long fiber effects are calculated from the input signal, fibercharacteristics, some OTX parameters, frequency range andprevious fiber lengths.

optloss name

optloss type

fiber

splitter

connector

add.loss

order

tap attenuation

tap output

Simulation behavior


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5.7 Coaxial Loss

Figure 17 Coaxial Loss Dialog Box

Use the Load and Save buttons to load or save the CoaxLossmodule from or to disk, respectively. Use OK to terminate editing.Use the Cancel button to terminate editing without affecting any

changes. The module is defined by its attenuation in dB.

The name of the Coaxial Loss (coaxial access network) can befreely defined.

Select a coax splitter: 1:1 for none, 1:2, 1:4, 1:8. These splittershave predefined attenuations. To use other values, define themwith additional loss.

Indicates an attenuation which is added to the splitter attenuation.

Indicates the total attenuation of the module.

coaxial name

splitter

additional loss

total coax loss


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This module simply inserts attenuation.

5.8 Optical Receiver (ORX)

Figure 18 Optical Receiver Dialog Box

Use the Load and Save buttons to load or save the ORXmodule from or to disk, respectively. Use OK to terminate editing.Use the Cancel button to terminate editing without affecting any

changes. The ORX module is defined by the parameters listedbelow, which can only be changed in Expert mode when no libraryis active. When editing a library model, only the output level can

Simulation behavior


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be changed. None of the parameters are servicerelated, meaningthey are related to the nonlowered carrier level. The CSO/CTBreference values, however, are the maximum values in thefrequency range of the selected service. Ensure that the CSO or

CTB beats are present between these band limits when changingthese values in order to prevent undefined behavior of thesimulation model.

The name of the Optical Receiver can be freely defined.

This field describes the amplifier section of the ORX.

Indicates the electrical output level in dBmV at 862 MHz.

The Pilot Controlled checkbox indicates that the output level isalways constant. The cw controlled checkbox indicates that theoutput level is independent of the optical input level. If the ORX isneither pilot nor cw controlled, the output is dependent on thechannel modulation index and the optical input power. If the ORXis not pilot controlled the output power can be changed indirectlyby adjusting the gain of the amp section.

Indicates the pre-emphasis for the frequency span from 47 .... 862MHz in dB.

Indicates the CSO contribution of the amplifier section at thereference output level.

Indicates the CTB contribution of the amplifier section at thereference output level.

Indicates the reference output level for the CSO and CTBcontributions.

Indicates the maximum output level of the ORX.

o/e section

This section describes the optical/electrical conversion of theORX.

Indicates the CSO contribution of the o/e section at the referencechannel modulation index and reference input power.

Indicates the CTB contribution of the o/e section at the referencechannel modulation index and reference input power.

orx name

amp section

output level

pilot/cw controlled

preemphasis

CSO

CTB

ref.

limit

CSO

CTB


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Indicates the reference channel modulation index for the CSO andCTB contributions.

Indicates the maximum input level and reference input power forthe CSO and CTB contributions.

Indicates the dependency of the effective noise current on theoptical input power.

Indicates the effective responses in two optical windows.

The "IM" button opens the dialog box Parameter for IM simulation(refer to Figure 26).


at

limit and ref.

eff. noise current

eff.res./at

Simulation behavior


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5.9 Module

Figure 19 Module Dialog Box

Enter a MODULE in the Module dialog box to add a module withfixed contributions and a fixed output level. Use the Load andSave buttons to load or save the module from or to disk,respectively. Use OK to terminate editing. Use the Cancelbutton to terminate editing without affecting any changes. TheMODULE is specified with the following parameters. None of theparameters are servicerelated, meaning they are related to the

nonlowered carrier level.


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The name of the MODULE" (fixed additional contribution) can befreely defined.

Indicates the CNR, CSO and CTB as fixed contributions. Thesevalues are the maximum values in the frequency range of theselected service.

Indicates the output level as an electrical value in dBmV whenusing MODULE with an electrical input signal, and as an opticalvalue in dBm when using MODULE with an optical input signal.

Indicates the equivalent noise bandwidth to which the CNRcontribution is related.


Fixed contributions for CSO, CTB and CNR are added.

module name

contributions

output level

channel bandwidth

Simulation behavior


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5.10 Optical Insertion

Figure 20 Optical Insertion Dialog Box

Use the Load and Save buttons to load or save the OpticalInsertion module from or to disk, respectively. Use OK toterminate editing. Use the Cancel button to terminate editing

without affecting any changes. None of the parameters areservicerelated, meaning they are related to the nonloweredcarrier level.


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The name of the optical insertion can be freely defined.

The input insertion path is defined by its input level, input CNR andinsertion loss.

It is possible to define whether the modulation index should beautomatically adjusted for equal carrier levels of main andinsertion paths at the output, or freely defined.

It is possible to define whether the insertion loss of the main pathshould be automatically adjusted complementary to the insertionpath, or freely defined.

This module is for the insertion of a second optical signal path.Only CNR is considered. The new modulation index at the outputis calculated.

optical name

input insertion path

modulation indexinsertion path

insertion loss mainpath

Simulation behavior


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5.11 Coaxial Combiner

Figure 21 Coaxial Combiner Dialog Box

Use the Load and Save buttons to load or save the Combinermodule from or to disk, respectively. Use OK to terminate editing.Use the Cancel to terminate editing without affecting any

changes. The module is defined by its concentration factor. Thecorresponding insertion loss is displayed.


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The name of the Coaxial Loss (coaxial access network) can befreely defined.

This can be changed in steps of 2n.

This value indicates the insertion loss of the combiner itself. It maybe different from the modules attenuation in automatic attenuationmode.

Indicates a combiner with no insertion loss.

The number of carriers (channels) is multiplied by the number ofinputs.

The attenuation is adapted to keep the total load constant whenthe channel number is changed. (The attenuation cannot be lowerthan the minimum insertion loss.)

In this mode, the number of channels at the output can beoverwritten.

The combiner reduces the CNR by 3xn dB at a concentration

factor of 2^n. This is due to addition of several input noise signals.CSO and CTB are left unchanged.

combiner name

concentration factor

min. insertion loss

no input loss

multiply carrier

auto attenuation

define eq. Number(of channels atoutput)

Simulation behavior


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5.12 Return Channel Noise

Figure 22 Return Channel Noise Dialog Box

Use the Load and Save buttons to load or save your ReturnChannel Noise module from or to disk, respectively. Use OK to

terminate editing. Use the Cancel button to terminate editingwithout affecting any changes.


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The name of the RCNoise module (coaxial access network) can

be freely defined.

Indicates the number of passed homes (coax cell size).

Indicates the parameters that define radio background noise; theycan only be changed in Expert mode.

Changing these parameters is only possible in Expert mode.Ingress noise is simulated either with a reference network ormeasured network. In case of a reference network, ingress noiseis described by means of three parameters. In case of a measured

network, it is defined as a list of interferers. A list of interferers canbe loaded from an ING-file via the "Load" button.

This threshold indicates a maximum impulse noise amplitude for amaximum BER at the output of the last module in the schematic. Ifthe schematic is not calculated (after changing some module data)or the maximum BER is lower than the BER after the last module,the threshold is displayed. The input for a max. BER can only beentered in Expert mode.

The combiner reduces the CNR due to addition of several inputnoise signals. CSO and CTB are left unchanged.

RCNoise name

homes passed

radio backgroundnoise per home

ingress noise

impulse noiseamplitude threshold

Simulation behavior


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5.13 Module list

Module lists handle two combined modules like a single module.There are three predefined modul lists offered:

an OTX combined with a LCA to represent an OTXE090

a double stage amplifier

a combiner with an amplifier to represent an UCC

Figure 23 Available module lists

A double click on a module list opens a dialog where the twounderlying modules are visible.


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Figure 24 Opened module list

The two underlying modules can be treated separately likeexplained before, e.g. opened with a click.

A double click in the dark grey area closes the module list andshows the combined module like before.

A right mouse click in the dark grey area opens a dialog whichallows to save the module list.


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6 Procedures

6.1 Working with Libraries

This is the normal use for SPAC. A library contains simulationmodels for optical transmitters, optical receivers, optical amplifiersand coaxial amplifiers. There are readonly libraries (with theextension .dll) which are delivered with SPAC, and user libraries

(extension .lib) which can be created by the user. Select a libraryby using the list box in the tool bar. If a library is selected in thetool bar (user or readonly, refer to Section 4.2), no editing ofmodule data is possible (except SOURCE, OptLoss, OptInsert,CoaxLoss, Combiner, RCNoise and MODULE which cannot havelibrary models, and the output level of the ORX). A readonlylibrary is indicated in a schematic by a special icon and the libraryname is displayed in the Edit Dialog Box as well as in the print out.

Detailed information concerning the simulation models in thereadonly libraries is available by clicking on the right mousebutton in the title bar of a library model. This information can alsobe called in by clicking on the Info button from Load in the Librarydialog box. This dialog box is opened after adding a module from areadonly library.

6.2 Modifying Modules

Library models can only be modified in Expert mode. The librarymust then be disabled by selecting [.] from the library list box in the

tool bar. The module data can then be changed using the Editmodule in the Edit menu.

Expert mode can also be used to create userdefined modules(refer to Section 4.3.4 ). If a library is selected and SPACcalculates the schematic, SPAC always tries to use a library modelinstead of a user created module. To prevent SPAC from replacinguserdefined models with library models, disable the library byselecting the sign [.] in the library list box in the tool bar. Replacingwith a library model occurs when the same library names are

used. The library name is the file name given to the library modelwhen it was saved to disk.


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6.3 Creating User Libraries

NOTICE

This function is only available in Expert mode.

To create a user library, create a directory with the extension .lib inyour SPAC directory (e.g. using the with Windows File Manager).After saving a module in such a directory (refer to Section 5.1), amodel is created in the user library. A default source module must

always be saved in a user library. This default source determinesthe regulation parameters of the CATV source when using thelibrary.

6.4 Edit Channel Table

Select the Edit Channel Table... from the Channels menu toopen the Channel Types window illustrated in the figure below.


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Figure 25 Channel Type List

This dialog is used for enabling and disabling single services ofthe actual channel table. The back off level of each channel typecan be edited. This concerns the amount which a specific servicelevel is lowered. The default values are read from the channel listfile.

modulated carriers must be selected in order to run SPQA!Simulation (refer to Chapter 4.3.10) .

Select the button of a channel type in the Channel Typeswindow to open the Edit Channel Table window, illustrated in thefollowing figure.


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Figure 26 Edit Channel Table

This dialog is used to enable or disable single channels of aservice. The sound carriers of TV channels can be enabled ordisabled using the checkbox enable sound carriers. The channelbandwidth edit field displays the default bandwidth read from thechannel list file for this service. It can be overwritten.

NOTICE

The letters in the channel table depend on the service operator

and country. The letter required can be selected by the user fromthe channel list file.


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6.5 Channel List File

A channel list file is a file with the extension *.lst. It is used todefine the channel allocation. The channel list file can be editedwith a standard text editor. When the command Edit Channel Listis entered in the Channels Menu, Windows Notepad (or anothereditor defined) is opened in which to edit a channel list file. IfWindows 95 is used, the file type *.lst must be registered.Otherwise, NOTEPAD cannot be used to edit and save newchannellist files.

The channel allocation is defined in the following form:1. Add a [channels] section into the file. The following are

supported:

[VSBAM] for VSBAM (video) channels

[FM] for FM (audio) channels

[256QAM] for 256QAM channels




[16QAM] for 16 QAM channels

[8QAM] for 8 QAM channels

[DQPSK] for DQPSK channels

[QPSK] for QPSK channels

[FSK] for FSK channels

[PSK] for PSK channels


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Add a line in the following format to add a channel orcarrier:

name = cf,lr,ds,rs

with

name = name of channel which is displayed in theEdit Channel Table dialog.

cf = frequency of video carrier in MHz(frequencies have to be entered in stepsof 50 kHz)

lr = level reduction of video carrier in dBrelative to service backoff

ds = distance of sound carrier to video carrierin MHz

rs = level reduction of sound carrier in dBrelative to video carrier.

If the last items of a line are omitted, the simulatorassumes the default values. These are 0 dB for levelreductions and no sound carrier.

2. Add a [REF] section.

In order to define a level backoff for each service (e.g.64 QAM channels are normally reduced by 10 dBagainst analog video carriers), add an entry in thefollowing form:

[REF]

FM=4

64QAM=10


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NOTICE

It is important to set the references to proper values, becausethe simulated CNR, CSO, CTB, MER and BER are always

related to the level backoff of the selected service !

3. To specify other channel bandwidths as the integrated defaultvalues, add a [BANDWIDTHS] section containing entries for eachservice bandwidth. The example below illustrates this:

[BANDWIDTHS]

VSBAM=4e6

The default values relate to VSBAM 5 MHz, FM 150

kHz, 16QAM 3,2 MHz, 64QAM 8 MHz, DQPSK 2,25MHz, QPSK 3,2 MHz, FSK and PSK 300 kHz

Sample with 2 TV channels ( K2 and K4) but no levelreduction, sound carrier at 5.5 MHz above with 13 dBlevel reduction, FM channels with 4 dB level reduction,QAM channels with 10 dB level reduction.

4. Sample channel list file

Sample with 2 TV channels ( K2 and K4) with no levelreduction, sound carrier at 5.5 MHz above with 13 dBlevel reduction, FM channels with 4 dB level reduction,QAM channels with 10 dB level reduction.

[REF]

FM=4

64QAM=10

[VSB-AM]

K2=48.25,0,5.5,13

K4=62.25,0,5.5,13

.

.

[FM]

U1=87.55

U2=87.85

.

.

[64QAM]

K38=610.00

K39=618.00


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7 IM Simulator

7.1 Using the IM Simulator

After activating the IM simulator in the IM Simulator menu, theCSO, CTB and MER contributions are calculated and displayed inthe schematic.

The simulator is initialized when the SPAC is started up. Thesimulator requests a channel allocation through the Read ChannelList dialog. After selecting a channel list, the simulator completes

its initialization. For an automatic initialization at startup with thelast used channel list file, select Always use last channel list atstartup from the Channels Menu. The following icon appears forthe IM Simulator:

Figure 27 IM Simulator Icon

The IM spectrum at the output of the last module is displayed inthe IM simulator window (to display the simulator window press+ or use the IM Simulator menu in the main menu ofSPAC). To show the contributions of a single module, simplyselect the IM button in the modules edit dialog.

Use the vertical and horizontal scroll bars in the simulator windowto scroll through it. To scroll vertically, use the and keys. No scrolling is possible when the spectrum is

displayed at full scale.

Information on the current marker position is displayed below thesimulator window:

Indicates the CSO or CTB at the marker position.

Indicates the sum of the CSO and CTB at the marker position.

CSO/CTB

TOT


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7.2 IM Calculating Options

The Calculating Options dialog box can be used to change theband li

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