Juniper ACX500 Hardware Manual page 94

ACX500 Universal Access Router Hardware Guide
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Table 27: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Fiber attenuation
The following sample calculation for a 2-km-long multimode link with a power budget
(P ) of 13 dB uses the estimated values from
B
(LL) as the sum of fiber attenuation (2 km @ 1 dB/km, or 2 dB) and loss for five connectors
(0.5 dB per connector, or 2.5 dB) and two splices (0.5 dB per splice, or 1 dB) as well as
higher-order mode losses (0.5 dB). The power margin (P
P = P – LL
M B
P = 13 dB – 2 km (1 dB/km) – 5 (0.5 dB) – 2 (0.5 dB) – 0.5 dB
M
P = 13 dB – 2 dB – 2.5 dB – 1 dB – 0.5 dB
M
P = 7 dB
M
The following sample calculation for an 8-km-long single-mode link with a power budget
(P ) of 13 dB uses the estimated values from
B
(LL) as the sum of fiber attenuation (8 km @ 0.5 dB/km, or 4 dB) and loss for seven
connectors (0.5 dB per connector, or 3.5 dB). The power margin (P
follows:
P = P – LL
M B
P = 13 dB – 8 km (0.5 dB/km) – 7(0.5 dB)
M
P = 13 dB – 4 dB – 3.5 dB
M
P = 5.5 dB
M
In both examples, the calculated power margin is greater than zero, indicating that the
link has sufficient power for transmission and does not exceed the maximum receiver
input power.
Understanding Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion on page 71
Estimated Link-Loss Value
Single-mode—0.5 dB/km
Multimode—1 dB/km
Table 27 on page 73
) is calculated as follows:
M
Table 27 on page 73
Copyright © 2016, Juniper Networks, Inc.
to calculate link loss
to calculate link loss
) is calculated as
M