Keysight Technologies N77 Series User Manual page 67

Keysight N77xx Series
Relative uncertainty of monitor power meter
When changing the output power of the attenuator, the relative power
meter uncertainty is the maximum error of the displayed output power
ratio to the actual output power ratio. This uncertainty is caused by the
internal power meter's nonlinearity and noise and by errors in the
sensing hardware, expressed as ± half the span of all possible errors
with an offset due to the noise level of the power meter. Symbol RU.
Conditions: Reference power level 1mW, wavelength and polarization
state constant; power limitations as in the Specifications; zeroing prior
to measurement.
Measurement: The nonlinearity is calculated using the displayed power
ratio D2 / D1 and the corresponding actual power ratio P2 / P1:
The relative power meter uncertainty is then calculated using:
RU is then expressed in dB and the offset is expressed in pW.
Absolute power accuracy attainable with the help of an external optical power
N O T E N O T E
meter.
Repeatability (of attenuation/total loss, or power level)
the uncertainty in reproducing the
"Attenuation" on page
"Total loss" on page 70 (or
59, or power level) after randomly changing
Specifications and Regulations
Compliance 3
Specifies
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