Measurement Computing eZ-PostView rev.2.0 User Manual
Page 66
3-8 Menus
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eZ-Analyst
Calibrator
Type
This column is used to select Peak or RMS* as the calibrator type. Highlight a
cell, or range of cells, in the grid, then select Peak or RMS from the popup
menu.
Peak Uses the peak amplitude of the spectrum around the specified frequency of the
calibration signal.
RMS Uses a compensated overall level calculation to determine the RMS level of the
calibration signal, as specified in the Units field.
*RMS – Root-mean-square, is the square root of the arithmetic mean of the
squares of a set of numbers.
Calibrator
Scale
This column is used to select the calibrator scale to linear or to decibel.
Lin Select Lin if the calibrator is in linear scale.
dB Select dB if the calibrator scale is dB.
Note: While there are several definitions to dB, in our application we are
using dB to express the ratio of the magnitudes of two quantities equal
to 20 times the common logarithm of the ratio.
The formula for dB is:
dB = 20 log (x/dBEUref)
EU dB
Reference
This field is used to enter the Engineering Units dB reference.
dB EU Reference is applied to displayed data when the Y-axis scale is set to dB.
This is valid only for frequency domain data.
Note: The dB Reference (Volt) can be changed simultaneously for all channels
from the associated entry box in the FFT Setup Tab. The tab is accessed
from the Configuration Window [via the Edit pull-down menu].
The formula for dB display for Unaveraged Spectrum, Averaged Spectrum, and
FRF is:
dB = 20 log (x/dBEUref)
The formula for dB display for Autospectrum, Cross Spectrum, and PSD is:
dB =10 log [x/((dBEUref)^2)]
Calibrator
EU
This field is used to set the Calibrator’s Engineering Units.
Measured
mV
Displays the measured value of the channel in milli-volts.
Transducer
mV/EU
The Transducer mV/EU value can be entered manually, or by the
measurement process. Highlight a cell, or cells, in the grid before typing a
value in the data entry box. Then press the
value. All other fields linked to this value are updated when the value is
accepted.
mV/EU= Volts/Units * Transducer Gain
EU Offset
EU Offset is used for DC signal compensation. Offset is added to, or
subtracted from the measured EU value.