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specified for the type of link in the Telcordia Technologies document GR-253-CORE (Section 4.3) and
International Telecommunications Union (ITU) document G.957.
When chromatic dispersion is at the maximum allowed, its effect can be considered as a power penalty in
the power budget. The optical power budget must allow for the sum of component attenuation, power
penalties (including those from dispersion), and a safety margin for unexpected losses.
Calculating the Fiber-Optic Cable Power Budget for an MX10016
Calculate the link's power budget when planning fiber-optic cable layout and distances to ensure that
fiber-optic connections have sufficient power for correct operation. The power budget is the maximum
amount of power the link can transmit. When you calculate the power budget, you use a worst-case
analysis to provide a margin of error, even though all the parts of an actual system do not operate at the
worst-case levels.
To calculate the worst-case estimate for the fiber-optic cable power budget (P
1. Determine values for the link's minimum transmitter power (P
For example, here, (P
(dBm):
P
= –15 dBm
T
P
= –28 dBm
R
NOTE:
See the specifications for your transmitter and receiver to find the minimum transmitter
power and minimum receiver sensitivity.
2. Calculate the power budget (P
–15 dBm – (–28 dBm) = 13 dBm
Calculating the Fiber-Optic Cable Power Margin for an MX10016
Calculate the link's power margin when planning fiber-optic cable layout and distances to ensure that
fiber-optic connections have sufficient signal power to overcome system losses and still satisfy the minimum
input requirements of the receiver for the required performance level. The power margin (P
amount of power available after attenuation or link loss (LL) has been subtracted from the power budget
(P
).
B
) and (P
) are measured in decibels, and decibels are referenced to 1 milliwatt
T
R
) by subtracting (P
B
) and minimum receiver sensitivity (P
T
) from (P
):
R
T
) for the link:
B
) is the
M
118
).
R
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