0
$\begingroup$

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 $var_{sig}$?

Improve this question
$\endgroup$
2
  • $\begingroup$ Hi, welcome to Engineering. If I understand correctly your question can be reduced to "How can I convert $var_{adc}$ units ($V_{rms}$) to $g_{rms}$ which are compatible with the rest of the quantities. " $\endgroup$
    – NMech
    Dec 11, 2020 at 6:47
  • $\begingroup$ Yes that would be one thing to conver the Vrms to grms. Do i need to consider any other factors or it is just straight forward substituition into the summation equation and calculate the unknown $\endgroup$
    – Elvir Peco
    Dec 11, 2020 at 21:27

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.