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Table 25: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Modal and chromatic
dispersion
Connector
Splice
Fiber attenuation
Clock Recovery Module
(CRM)
NOTE:
For information about the actual amount of signal loss caused by equipment and
other factors, see your vendor documentation for that equipment.
2. Calculate the (P
) by subtracting (LL) from (P
M
P
– LL = P
B
M
13 dBm – 0.5 dBm [HOL] – 5 (0.5 dBm) – 2 (0.5 dBm) – 2 km (1.0 dBm/km) – 1 dB [CRM] = P
13 dBm – 0.5 dBm – 2.5 dBm – 1 dBm – 2 dBm – 1 dBm = P
P
= 6 dBm
M
The calculated power margin is greater than zero, indicating that the link has sufficient power for
transmission. Also, the power margin value does not exceed the maximum receiver input power. Refer
to the specifications for your receiver to find the maximum receiver input power.
Estimated Link-Loss Value
Multimode—None, if product of
bandwidth and distance is less
than 500 MHz/km
Single-mode—None
0.5 dBm
0.5 dBm
Multimode—1 dBm/km
Single-mode—0.5 dBm/km
1 dBm
):
B
Sample Link Loss (LL) Calculation Values
0 dBm
0 dBm
This example assumes five connectors. Loss for five
connectors: 5 (0.5 dBm) = 2.5 dBm.
This example assumes two splices. Loss for two
splices: 2 (0.5 dBm) = 1 dBm.
This example assumes the link is 2 km long. Fiber
attenuation for 2 km: 2 km (1 dBm/km) = 2 dBm.
This example assumes the link is 2 km long. Fiber
attenuation for 2 km: 2 km (0.5 dBm/km) = 1 dBm.
1 dBm
M
56
M
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