Juniper PTX1000 Hardware Manual page 68

Table 26: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Modal and chromatic dispersion
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
Single mode—None
Multimode—None, if product of bandwidth and distance is less than
500 MHz-km
0.5 dB
0.5 dB
Single mode—0.5 dB/km
Multimode—1 dB/km
Table 26 on page 67 to calculate link loss (LL) as the sum of fiber attenuation
Table 26 on page 67 to calculate link loss (LL) as the sum of fiber attenuation
68
) of 13 dB uses
B
) is calculated
M
) of 13 dB
B