Juniper MX10003 Hardware Manual page 76

Table 30: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Connector
Splice
Fiber attenuation
The following sample calculation for a 2-km-long multimode link with a power budget (P
the estimated values from
(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
as follows:
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
uses the estimated values from
(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 ) is calculated as follows:
M
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.
Estimated Link-Loss Value
0.5 dB
0.5 dB
Single mode—0.5 dB/km
Multimode—1 dB/km
Table 30 on page 75 to calculate link loss (LL) as the sum of fiber attenuation
Table 30 on page 75 to calculate link loss (LL) as the sum of fiber attenuation
76
) of 13 dB uses
B
) is calculated
M
) of 13 dB
B