How to Calculate the Fiber-Optic Cable Power Budget for EX Series Switches
To ensure that fiber-optic connections have sufficient power for correct operation, 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 fiber-optic cable power budget (PB) for the link:
- Determine values for the link's minimum transmitter power
(PT) and minimum receiver
sensitivity (PR). For
example, here, (PT) and
(PR ) are measured in
decibels, and decibels are referred to one milliwatt (dBm).
PT = – 15 dBm
PR = – 28 dBm
See the specifications for your transmitter and receiver to find the minimum transmitter power and minimum receiver sensitivity.
- Calculate the power budget (PB) by subtracting (PR) from (PT):
– 15 dBm – (–28 dBm) = 13 dBm