EXFO FTB-1 - Manual (Page 127)

FTB-1 117
6 Using the Optional Built-In
Power Meter and VFL
The FTB-1 can be equipped with an optical power meter to measure
absolute power (dBm or W) or insertion loss (dB). The power meter can
detect modulated signals (1 kHz, 2 kHz, and 270 Hz).
The FTB-1 can also include a visual fault locator (VFL) to inspect or identify
fibers.
If you have purchased a module with an inline power meter, you can also
take measurements with this power meter instead of using the built-in
power meter.
For more information on how to use the power meter or the VFL, refer to
the power meter online help.
Note: The appearance of your application may vary depending on the options
that you have purchased and the module you are using. The illustrations
presented hereafter show the application as it appears when the unit is
equipped with a built-in power meter, a built-in VFL, and a module with an
inline power meter.