Juniper EX4200 Hardware Manual page 77

Table 22: 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
M
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 specification 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 (LL) Calculation Values
0 dBm
0 dBm
This example assumes 5 connectors.
Loss for 5 connectors:
(5) * (0.5 dBm) = 2.5 dBm
This example assumes 2 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) * (1.0 dBm/km) = 2 dBm
(2 km) * (0.5 dBm/km) = 1 dBm
1 dBm
M
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