Juniper MX10008 Hardware Manual page 123

Table 47: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
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
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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.
SEE ALSO
Understanding Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion
Estimated Link Loss Value
Multimode—1 dBm/km
Single-mode—0.5 dBm/km
1 dBm
):
B
Sample Link Loss (LL) Calculation Values
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
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