Measurement Computing eZ-Analyst rev.14.1 - Manual (Page 25)

eZ-Analyst 878193 Menus 3-7
Columns on the Calibration Window
No. This column displays channel numbers [1, 2, 3, … etc.] for easy reference to
their associated cells. The channel numbers, being for display indication only,
are fixed and can not be edited.
Active When “Single Channel” is selected, you can click on a radio button in the
“Active” column to enable one channel for calibration. When the calibration is
complete, select the radio button for the next channel to be calibrated.
When “Multiple Channel” is selected, the radio buttons are replaced by
checkboxes. Ensure that each channel to be calibrated has the associated box
checked, and that the remaining channels remain unchecked. For multiple
channel applications note that you can click on the column label, i.e., the word
“Active” to simultaneously check or uncheck all channel checkboxes in the
column.
Note: The channel settings in the Calibration window are independent of the
selections that appear in the Input Channel Setup window. Only active
channel shows up at calibration window.
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)]