Measurement Computing eZ-Record rev.2.1 - Manual (Page 27)

27
January 2001 eZ-Record Manual
T
ASK
M
ENU
M
EASUREMENT
Select Measurement to activate the Record and Scope buttons on the Task bar.
P
LAYBACK
/ R
EVIEW
Select Playback/Review to activate the Playback Controls on the Task bar.
C
ALIBRATION
Transducer calibration may be performed when a calibration signal of a
known level or RMS content is available. The known signal can be applied to
the transducer connected to an input channel. Two types of calibrators are
commonly used; 1) desktop calibrators for transducers such as
accelerometers, strain gauge, etc. and 2) piston phones for microphone
calibration. Linear engineering units are commonly used for the former type
and dB engineering units for the latter type.
After calibration is finished, the measured voltage(s) for the selected
channel(s) is(are) displayed in the Volts field and used in the calculation of
EU/Volt.
Note: When using one calibrator, you can only calibrate one channel at a time.
No.: This column lists the channels of the Medallion Data Acquisition Module.
Active: True, False. Select True for each channel to be calibrated. Select False
for each channel not to be calibrated. Note: This is independent of
selections in the Input Channel Setup window.
Type: Peak, RMS. Highlight a cell, or range of cells, in the grid before selecting a
Calibration Type on the popup menu.
Peak uses the peak amplitude of the spectrum around the specified
frequency of the calibration signal. The measured peak voltage is entered
into the “Volt” field and further used to determine “EU/Volt”. Please see
the section, “Performing Calibration”, for examples. It searches total seven
spectral lines for the peak; three lines on either side of the specified
calibration frequency.
RMS uses a compensated overall level calculation to determine the RMS
level of the calibration signal, as specified in the Units field. The overall
calculation compensates for the effect of low frequency noise in the
calibration signal by ignoring the first four spectral lines.