Larson Davis HVM100, Manual

Page: 161 / 174

4/11/03 E -3
NOTE: Using the typical values of 600 mV (1g) and 500 mV
(0.1g), the calculated sensitivity would be 5 mV/dB. Note
that the sensitivity is the same regardless of the DC output
setting (i.e. rms, sum, min, max, peak).
Step 11
To convert a DC output voltage to units of g, use
the following formula:
NOTE: The formula is the same regardless of whether the
DC output is being used to measure rms, min, max, or peak
acceleration. The only difference is the reference voltage
(i.e. the voltage @ 1g). If the DC output is set for rms, min,
or max, the reference voltage is the voltage @ 1g rms. If the
DC output is set to peak, the reference voltage is the voltage
@ 1g peak.
AC/DC Outputs
DC Output
For all of the Analog AC and Analog DC outputs, the output
impedance of the HVM100 is 475 ohms. For minimal error,
connect to instruments with an input impedance of greater
than 100,000 ohms when making AC or DC output measure-
ments.
DC output sensitivity = 5 mV/dB (typical). The level varies
between 0 Vdc to 1.0 Vdc.
Since the sensitivity is fixed at approximately 5 mV/dB, the
DC output signal is not affected by the user’s selection for
“display units” or the user’s selection of the dB reference
value (i.e. 10
-6
m/s
2
or 10
-5
m/s
2
).
DC output (g) = 10
[(present voltage) - (voltage @ 1g)] / (DC output sensitivity) x 20