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How to Remove Electrical Offsets (Zero)
Keysight N77xx Series
The N7766A and N7768A multimode attenuators accept controlled
speeds between 0.1 and 80 dB/s and a full speed of about 1000 dB/s.
Settings above 80 dB/s will result in full-speed operation.
The optical power meters in the attenuator measure optical power by
converting optical power to electrical current, and then measuring
electrical current. An electrical offset is electrical current that is always
present, even if there is no optical power input. If electrical offsets are
not removed, they affect the accuracy of attenuation and power control,
especially at low optical power levels.
Performing a zero sets the zero power level to the average electrical
offset level for the current environmental conditions.
The environmental conditions and the temperature of the instrument affect
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electrical offset.
For the best results you must:
•
Allow the instrument time to acclimatize (around 24 hours).
•
Allow the instrument time to warm up (around 20 minutes).
•
Make sure that the optical input and output is not receiving any light.
If you are using multi-mode fiber-optic cable, you must disconnect
the cable and cover the input and the output of the attenuator to
perform a zero.
It is good practice to perform a zero before making any sensitive
measurements.
While zeroing an attenuator's power monitor or an integrated power meter, all
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attenuators in the unit are stopped and all shutters are closed to ensure the best
possible zeroing performance.
1 In the File menu, select Zeroing.
Attenuation 2
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