Table 38: Estimated Values for Factors Causing Link Loss
(Continued)
Link-Loss Factor
Estimated Link-Loss Value
Sample Link-Loss Calculation Values
Modal and chromatic
dispersion
Multimode—None, if product
of bandwidth and distance is
less than 500 MHz/km
0 dBm
Single mode—None
0 dBm
Connector
0.5 dBm
This example assumes five connectors. Loss for
five connectors: 5 (0.5 dBm) = 2.5 dBm.
Splice
0.5 dBm
This example assumes two splices. Loss for two
splices: 2 (0.5 dBm) = 1 dBm.
Fiber attenuation
Multimode—1 dBm/km
This example assumes the link is 2-km long. Fiber
attenuation for 2 km: 2 km (1 dBm/km) = 2 dBm.
Single-mode—0.5 dBm/km
This example assumes the link is 2-km long. Fiber
attenuation for 2 km: 2 km (0.5 dBm/
km) = 1 dBm.
Clock Recovery Module
(CRM)
1 dBm
1 dBm
NOTE: For information about the amount of signal loss caused by equipment and other
factors, see your vendor documentation for that equipment.
2. Calculate the (P
M
) by subtracting (LL) from (P
B
):
P
B
– LL = P
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
M
P
M
= 6 dBm
100
