EXFO PPM-350C PON Power Meter - Manual (Page 18)

Getting Started with Your PON Power Meter 12
Nulling Electrical Offsets
Temperature and humidity variations affect the performance of electronic circuits
and optical detectors. Nulling the electrical offsets eliminates these effects. Your
unit has been designed not to require offset nulling under normal operation, but you
should perform it whenever environmental conditions change significantly or when
measuring very low power values.
Note: Factory-defined values will be reinstated when you turn the unit off.
To perform an offset nulling:
Hold down and a few seconds.
The unit displays NULL and vertical bars move at
the top of the display, indicating the nulling is in
progress.
Note: Keypad is disabled during the operation.
The unit will then return to your previous mode (Pass/Fail or Normal).
I
MPORTANT
If light reaches the detector when nulling offsets, LIGH appears on
the display and the nulling is not performed. You will need to press a
key to return to the previous display.
Threshold/
 
Select