P
ref
is the chosen reference power value in Watts.
How to Set the Calibration Offset
This is a calibration offset that you can enter to compensate for external
optical circuitry, for example, an attenuator, switch, or a 3 dB coupler.
The calibration offset, [Cal], is automatically subtracted from the input
signal, as expressed in dB.
where,
P
measured
is the adjusted value of the signal read in dBm,
P
input
is the input signal level in dBm, and
CAL
is the calibration offset in decibels (dB).
How to Set the Reference Level
How to Input a Reference Level
dB results are shown relative to a reference level. Setting, or changing,
the reference only affects results that are returned in dB.
You can set the reference level in units of dBm or Watts. Depending on
which is selected the following equations are used to calculate the
power level in dB:
P
dB
= P
measured
(dBm) - REF(dBm)
or
where,
P
dB
is the returned relative power,
P
measured
is the absolute power level (see
), and
REF
is the reference level.
Power Measurement
2
Keysight N774x Series
49
Содержание N7744A
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