Calculating The Fiber-Optic Cable Power Budget For A Qfx Series Device; Calculating The Fiber-Optic Cable Power Margin For A Qfx Series Device - Juniper QFX5200 Hardware Manual

QFX5200 Switch Hardware Guide
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Calculating the Fiber-Optic Cable Power Budget for a QFX Series Device

Related
Documentation

Calculating the Fiber-Optic Cable Power Margin for a QFX Series Device

48
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 a QFX Series Device on page 48
Calculating the Fiber-Optic Cable Power Margin for a QFX Series Device on page 48
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
link:
Determine values for the link's minimum transmitter power (P
1.
sensitivity (P ). For example, here, (P
R
are referenced to 1 milliwatt (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.
Calculate the power budget (P
2.
–15 dBm – (–28 dBm) = 13 dBm
Understanding QFX Series Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion
on page 46
Calculating the Fiber-Optic Cable Power Margin for a QFX Series Device on page 48
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
) and (P ) are measured in decibels, and decibels
T R
B
) by subtracting (P ) from (P
R
Copyright © 2017, Juniper Networks, Inc.
B
) for the
) and minimum receiver
T
):
T