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HP4402.book : chapter2.fm 36 Wed Apr 23 15:29:05 1997
Power Meter Operation
Making Difference Measurements
2-36 HP EPM-442A User’s Guide
Making Difference Measurements
Dual channel difference measurements can be made on the currently
selected window by pressing , , and selecting
or . The power meter always carries out “Maths” calculations in
Watts. The power meter displays the numerical difference of the power
values of both channels in dBm or Watts. The power value for each
channel includes offsets, calibration factors and duty cycle in addition to
measured power. The filter, range (where applicable), offset, duty cycle
and calibration factor are set individually for each channel.
Logarithmic units (dBm) can be used in A-B difference measurements
where the channel A power level is less than the channel B power level.
Likewise, logarithmic units can be used in B-A difference measurements
where the channel B power level is less than the channel A power level.
However, the negative sign is ignored and a log error is displayed on the
status line and in the error queue.
Difference measurements can be displayed relative to a stored reference.
In relative mode readings are displayed in either dB or %. Refer to
“Making Relative Measurements”, on page 2-24 for further information.
Meas
Setup
Input Select
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A-B B-A