Vibration measurement of rotating blade

In a vibration measurement of a rotating blade, I have the following information. The vibration signal is measured using an ICP accelerometer which has the following specification

• Measurement range: 50g
• Sensitivity: 100 mV/g
• max output voltage: ±5V
• Broadband resolution: 100e-6g

The variance of the acquired signal is

$$var_{aq} = var_{acl} + var_{adc} + var_{sig} approx 6.2e-4 g$$

• $var_{acl}$ = variance of noise in the accelerometer
• $var_{adc}$ = variance of the ADC noise (quantization, jitter)
• $var_{sig}$ = variance of the vibration acceleration of the blade.

Assuming that $var_{acl} approx sqrt{text{broadband noise of accelerometer}} = 1e-8 text{g_rms}$.

From the specification sheet of the ADC, for the used input gain of 30db and sampling frequency = 51.2Hz, the $var_{adc} = 1e-12 text{V_rms}$

Can anyone please help, how can I calculate the variance of vibration acceleration of the blade $var_{sig}$?