Larson Davis HVM100, Manual

Page: 160 / 174

E-2 HVM100 User Manual 4/11/03
nels) based on the sensitivity of the accelerometer.
The values in the table assume that a calibrator
that vibrates 1g rms and 159.15 Hz, will be used.
Gain setting for various accelerometer sensitivities
Step 4
Connect a DC rms voltmeter to the DC output.
Step 5
Turn on the calibrator and start the HVM100 run-
ning. The HVM100 should display an Arms level
of 1 g.
Step 6
Note the voltage reading on the voltmeter. The
voltage corresponds to 1 g rms of acceleration.
The voltage will typically be about 600 mV for a 1
g rms input signal.
Step 7
Stop and Reset the HVM100. Reduce the calibra-
tor’s output level to 0.1 g rms. If this isn’t possi-
ble, change the HVM100’s weighting to Wh
(Hand-Arm mode). The Wh weighting will attenu-
ate the calibrator’s signal to 0.1 g rms (an attenua-
tion of 20.0 dB).
Step 8
Turn on the calibrator and start the HVM100 run-
ning. The HVM100 should display an Arms level
of 0.1 g.
Step 9
Note the voltage reading on the voltmeter. The
voltage corresponds to 0.1 g rms of acceleration.
The voltage will typically be about 500 mV for a
0.1 g rms input signal.
Step 10
The DC output uses a logarithmic scale. The for-
mula for the sensitivity is:
1 mV/g 10 mV/g 100 mV/g
Gain 60 dB 40 dB 20 dB
DC output sensitivity =
(voltage at 1g) - (voltage at 0.1g)
__________________________
20 dB