The OTDR 980MAS-P2 is with wavelength filter on its working wavelength 1610nm, so it can test active fibers (with signals in it). It is used for any normal situations, but you can not connected it with EDFA directly, because EDFA’s output power level is too high. The so high level laser will damage OTDR’s optical parts, and processing electronic circuits.

The permitted input power level for OTDR model 980MAS-P2 is 0dBm in max. For normal power level at subscriber side, it is around -20 to -35 dBm. So, 0dBm is enough for normal testing.