32Chapter 2 Calculating transmission distance

Table 5 shows typical loss values that can be used to calculate the transmission distance for the mesh ring network example in Figure 12.

Table 5 Mesh ring signal loss values

Signal loss element

value

 

 

Loss budget

30 dB

 

 

CWDM OADM insertion add loss

1.9 dB

 

 

CWDM OADM insertion passthrough loss

2.0 dB

 

 

CWDM OADM insertion drop loss

2.3 dB

 

 

System margin

3 dB

 

 

Fiber attenuation

.25 dB per km

 

 

Table 6 shows the calculations used to determine maximum transmission distance for the mesh ring network example in Figure 12.

Table 6 Mesh ring maximum transmission distance calculations

Result

Calculation

 

 

Passthrough nodes

nodes – 2

 

 

Passive loss

OADM add + OADM drop + (passthrough nodes × OADM passthrough loss )

 

 

Implied fiber loss

loss budget – passive loss – system margin

 

 

Maximum transmission

implied fiber loss ÷ attenuation per kilometer

distance

 

 

 

Transmission distance calculation for the mesh ring network example in

Figure 12:

8 nodes – 2= 6 Passthrough nodes

1.9 dB + 2.3 dB + (6 nodes × 2.0 dB)= 16.2 dB Passive Loss

30 dB – 16.2 dB –3 dB = 10.8 dB Implied Fiber Loss

10.8 dB ÷ .25 dB= 43.2 km Maximum Transmission Distance

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Nortel Networks 10292FA, 10396EA manual Mesh ring signal loss values, Mesh ring maximum transmission distance calculations