EXFO iOLM - Manual (Page 111)

Using the OTDR as a Source (Optional on Some Models)
intelligent Optical Link Mapper 105
3. Select the desired modulation from the Modulation list.
Select Continuous to receive the measurement loss with a power
meter at the other end.
Select 1 kHz or 2 kHz to identify the fiber under test, which could be
particularly useful when working with cables containing many fibers.
You can also select 1 kHz + Blink and 2 kHz + Blink for easier fiber
identification. If you select this pattern, the modulated signal (1 KHz or
2 KHz) is sent for 1 second, then is off for the next second, then be sent
again for 1 second, and so on.
4. Select Turn On to start emission.
Note: The application displays the source wavelength, source port, and the turn
on state in the status bar.