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28 Chapter 2 Calculating transmission distance
212257-B
How to calculate expected loss budget
To calculate the expected loss budget for a proposed network configuration:
1 Identify all points where signal strength will be lost.
2 Calculate the expected loss for each point.
3 Add the expected losses together.
How to calculate maximum transmission distance
The examples in this chapter use the following assumptions and procedure for
calculating the maximum transmission distances for networks with CWDM
GBICs, CWDM OADMs, and CWDM OMUXs.
Assumptions
The examples assume use of the values and information listed in Table 2.
Table 2 Assumptions used in calculating maximum transmission distance
Item Assumption
Cable Single mode fiber optic cable (SMF)
Repair margin 0
1
1 Use your organization’s expected repair margin for percentage of the total fiber plant loss for each
site-to-site fiber span.
Maximum link budget 30 dB
2
2 From specifications in
Installing CWDM Gigabit Interface Converters,
part number 212256-B
System margin 3 dB (allowance for misc. network loss)
Fiber attenuation .25 dB per kilometer
Operating temperature 0 - 40°C (32 - 104°F)
CWDM OADM expected loss
3
3 Multiplexer loss values include connector loss.
Use of “CWDM OADM specifications” on page 45
CWDM OMUX expected loss
3
Use of “CWDM OMUX specifications” on page 47