Name: 
 

Fiber Optic Design Case Study 2



Completion
Complete each statement.
 

 1. 

This is The FOA Online Design Self-Study Program Case Study No. 2.

This exercise covers the design of a Metropolitan Telecom Network

A medium sized town is connecting two COs with fiber optics, upgrading from old copper cables. 

co001-1.jpgco001-2.jpg

Basic System Information:
The total fiber/cable distance is 16 km. The cable is pulled underground in existing ducts and fusion spliced at 9 different points, plus 2 pigtails are spliced on the ends for termination.
The system will be transmitting at OC-48 speeds (2.5 Gb/s) and at some point will be using DWDM for maximum fiber utilization.


Please enter your name, CFOT/Membership number and date to begin this exercise.
 

 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 2. 

The system will be transmitting at OC-48 speeds (2.5 Gb/s) and will be using DWDM for maximum fiber utilization.

What will be the wavelength used for transmission?
a.
1310 nm
b.
1490 nm
c.
1550 nm
d.
1310 and 1550 nm
 

 3. 

Which one of the following fibers are appropriate for this network?

ITU G.652     
ITU G.653      
ITU G.654     
ITU G.655 
a.
Any of these fibers will work since the link is short
b.
Only non-zero dispersion shifted fiber
c.
Only low water peak fiber
d.
Only cutoff shifted fiber
 

 4. 

If the network is planned for upgrades to 10, 40 or even 100 Gb/s, which  fibers are the best choice for this network?

a.
Any  fiber will work since the link is short
b.
Only non-zero dispersion shifted fiber
c.
Only low water peak fiber
d.
Only cutoff shifted fiber
 

 5. 

The cable chosen is a loose-tube design because the cable must be _____.
a.
Water-blocked and armored
b.
Water-blocked and rated for high pulling tension
c.
Rated for aerial installation without a messenger
d.
UL Listed for flame retardance
 

 6. 

How many fibers should be in the cable?
a.
As few as possible to reduce cable size and weight
b.
As few as possible to reduce cable and splicing cost
c.
As many as possible to allow maximum flexibility and upgrades
d.
Only as many as needed
 

 7. 

In order to ensure the system will work on the cable plant being designed, it is necessary to have what information on the communication system intended for use on the cable plant?
a.
Wavelength
b.
Transmitter min/max power output
c.
Receiver min/max input powers
d.
All of the above
 
 
Typical Specifications
Provided for use as case studies for design labs in FOA courses.

Component Specifications
  
Fiber Loss 
Singlemode at 1310 nm0.4 dB/km (TIA 568: 1 dB/km)
Singlemode at 1550 nm0.25 dB/km
  
Splice Loss(TIA 568: 0.3 dB, all types)
Singlemode, fusion0.05 dB
Singlemode, mechanical0.3 dB
  
Connector Loss(TIA 568: 0.75 dB, all types)
Singlemode, adhesive/polish0.3 dB


Active Device and System Specifications
  
Digital Transceiver Specs1Power (dBm), T=transmit, R=receive
1310 laser  (>1 Gb/s)T: +3 to -3 dBm, R: -10 > -20
1550 laser  (>1 Gb/s)T: +3 to -3 dBm,  R: -10 > -20
Fiber AmplifierGain +17 dB
DWDM Module Loss  #channels/dB8 ch/4 dB, 16 ch/5dB, 32 ch/6 dB

Link margin specifications for most standardized fiber optic networks are on the FOA Tech Topics Site (http://www.thefoa.org/tech/Linkspec.htm). It should be used as a reference for designers and for the courses.
 

 8. 

Using the information supplied, calculate the cable plant loss budget for this link.
Use the infomation in the "Typical Specifications" narrative above.
a.
7.55 dB
b.
5.15 dB
c.
6.05 dB
d.
20.8 dB
 

 9. 

With just a single wavelength,  the transmitter output power may be between +3 and -3 dBm and the receiver needs power level to be between -10 and -20 dBm, will the system operate on this cable plant?
a.
Yes
b.
Yes, but only with a 5 dB attenuator at the transmitter end
c.
Yes, but only with a 5 dB attenuator at the receiver end
d.
No, it cannot work under any circumstances
 

 10. 

If DWDM is used,  with the transmitter output power and the receiver power level listed, the 32 channel DWDM module, will the system operate on this cable plant?
a.
Yes
b.
Yes, but only with an attenuator at the transmitter end
c.
Yes, but only with an attenuator at the receiver end
d.
No, it cannot work under any circumstances
 

Multiple Response
Identify one or more choices that best complete the statement or answer the question.
 

 11. 

What parameters should be tested and documented to confirm proper installation?
 a.
Continuity and polarity
 b.
Insertion Loss
 c.
OTDR traces
 d.
CD and PMD
 

 12. 

Testing of each fiber should be done as follows:
(Choose all the correct answers)
 a.
Insertion loss with a light souce and power meter at 1310 and 1550 nm
 b.
Insertion loss with a light souce and power meter, looking for insertion loss around 5.15 dB at 1550 nm
 c.
Take OTDR traces for each fiber to ensure each splcie is properly made and no excess stress was used in cable installation
 d.
Storage of OTDR traces for future reference and restoration
 

 13. 

If the links were to be installed aerially, what are the options for cable installation?
 a.
ADSS cable with appropriate hardware
 b.
Cable lashed to messengers or current cables
 c.
Figure 8 aerial cable
 d.
OFNR cable
 

 14. 

What should be included in the design documents to have the customer prepare for restoration in case of an outage?
 a.
Store complete link documentation
 b.
Save leftover cable for splicing
 c.
Save several splice closures
 d.
Post emergency contact information for techs who can do restoration.
 



 
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