Calculating Power Budget And Power Margin For Fiber-Optic Cables; Calculating Power Budget For Fiber-Optic Cable - Juniper MX240 Hardware Manual

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 Power Budget and Power Margin for Fiber-Optic Cables

Use the information in this topic and the specifications for your optical interface to calculate the power
budget and power margin for fiber-optic cables.
TIP: You can use the
transceivers supported on your Juniper Networks device.
To calculate the power budget and power margin, perform the following tasks:

Calculating Power Budget for Fiber-Optic Cable | 202

1.
Calculating Power Margin for Fiber-Optic Cable | 203
2.
Calculating Power Budget for Fiber-Optic Cable
To ensure that fiber-optic connections have sufficient power for correct operation, you need to calculate
the link's power budget, which is the maximum amount of power it 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 of power
budget (P ), you assume minimum transmitter power (P
B
P = P – P
B T R
The following hypothetical power budget equation uses values measured in decibels (dB) and decibels
referred to one milliwatt (dBm):
P = P – P
B T R
P = –15 dBm – (–28 dBm)
B
P = 13 dB
B
Hardware Compatibility Tool to find information about the pluggable
) and minimum receiver sensitivity (P
T
202
):
R