Larson Davis HVM100, Manual

Page: 47 / 174

4/11/03 Range Menu 4-3
Cal Level
Hint:
This setting is in the Range menu. To access the Range menu press the
RANGE
key and then use the
u
and
d
arrow keys to navigate
through the menu items.
NOTE: Calibrators operate at a variety
of frequencies. It is important that the
frequency weighting selection does not
affect the level of the calibration. In gen-
eral it is recommended to calibrate in the
Vibration mode, using the Fc frequency
weighting. This will only apply a band-
limiting filter from 6.3 Hz to 1250 Hz.
This should accommodate most vibration
calibrators.
The Cal Level screen will allow you to enter the operating
level of your calibrator. The frequency of the calibrator is
also important, please see the adjacent note. To enter a value
for your calibrator, go to the cal level screen, press the
c
key, use the
r
and
l
arrow keys to select the position
and use the
u
and
d
arrow keys to change the charac-
ters. When the proper level is entered, press the
c
key to
return to the Range menu.The level must always be entered
in g’s (rms).
During calibration the gain of the HVM100 should also be
set so that the level of the calibrator is within the HVM100’s
measurement range. For example, when using a 1.0 g rms
calibrator and an accelerometer with a sensitivity of approx-
imately 100mV/g, the gain should be set to 20 dB. For a 10
mV/g accelerometer, the gain should be set to 40 dB. A gain
of 60 dB is appropriate for a 1 mV/g accelerometer. See
appendix A for a complete listing of the HVM100’s mea-
surement range.
Calibrate X, Y, Z
Hint: This setting is in the Range menu. To access the Range menu press the
RANGE key and then use the
u
and
d
arrow keys to navigate
through the menu items.
The calibrate screens are used to calibrate individual chan-
nels using a calibrator attached to the accelerometer. To cali-
brate the HVM with the accelerometer’s published
sensitivity, see the next section in this manual. To calibrate:
C a l L e v e l
1 . 0 0 0 e + 0 0 g r m s
NOTE: To change the Cal Level parame-
ter, press the
c
key, use the
u
and
d
arrows to select the desired value, and
then use the
r
and
l
arrows to move
to the next position. Once all positions
are set press the
c
key or move to any
other part of the HVM100 to accept the
entry.