EXFO FPM-300 Power Meter - Manual (Page 16)

Measuring Power or Loss (FPM-300 and FOT-300) 11
Referencing Your Power Meter to a Source
In reference mode, your unit displays the loss created by the fiber under test only,
since a reference value is subtracted from the measured power.
Note: You must set a reference value separately for each wavelength.
Compatible sources (such as FOT-300 and FLS-300) can transmit a power value to
your power meter, avoiding the need for manual referencing.
To receive the reference power value from a compatible source:
1. Connect a compatible source to your power meter
(as shown below, with or without a fiber under
test).
2. Use the source to emit the signal that contains its
power value (see To change the signal modulation:
on page 16).

If reference value or units change, the power
meter beeps and displays
REF while detecting the special signal.

The new reference power is displayed in the top right corner (in dBm) and
current loss reading is automatically switched to dB.
Note: When using this feature, you cannot change the power meter’s
wavelength, units or reference power manually. The power meter
behavior is totally determined by the source.
I
MPORTANT
The value sent is not the source’s actual power. It is a user-defined
value that may not take the optical link’s loss into account.