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T320 Calculating Power Budget for Fiber-Optic Cable
To ensure that fiber-optic connections have sufficient power for correct operation, you must calculate the link's optical power budget, which is the maximum amount of optical power it can transmit. When you calculate the optical 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 optical power budget (PB), you assume minimum transmitter power (PT) and minimum receiver sensitivity (PR):
PB = PT – PR
The following hypothetical optical power budget equation uses values measured in decibels (dB) and decibels referred to one milliwatt (dBm):
PB = PT – PR
PB = –15 dBm – (–28 dBm)
PB = 13 dB
