Calibration

<p>ebook 9 is not written for specialists within calibration facilities. Rather, it is intended for those who use accelerometers (and microphones), so they will have some idea of uncertainties in their sensors. Their overall measurement uncertainties will no doubt be greater. </p>

<p>Calibration is an orderly procedure for determining the sensitivity of measurement systems including sensors. By sensitivity we mean the ratio between electrical output and mechanical input. </p>

<p>Examples include: </p>

<ul>

  <li>(acceleration) millivolts per g, millivolts per m/s2,</li>

  <li>(velocity) mv per in/sec, mv per mm/s, </li>

  <li>(displacement) mv per in, mv per mm,</li>

  <li>(force) mv per pound, mv/N. </li>

</ul>

<p>Ideally, this is an &ldquo;end to end&rdquo; calibration, displaying on a readout a value that matches the physical quantity that is being measured. </p>

<p>I&rsquo;m not using the word &ldquo;calibrate&rdquo; in another sense: an adjustment of sensitivity. No practical post-factory way to adjust the sensitivity of the vibration and shock sensors (pickups, transducers) described herein exists. </p>

<p>9.1. Do you use the word “calibrate” properly?


<p>9.2. Why must we calibrate?</p>

<p>9.3. Static calibration</p>

<p>9.4. Relatively crude checks</p>

<p>9.5. Absolute calibration</p>

<p>9.6. Accelerometer calibrations at NIST</p>

<p>9.7. Hand-held calibrators</p>

<p>9.8. Specialized shakers</p>

<p>9.9. Comparison calibration</p>

<p>9.10. Random vibration calibration</p>

<p>9.11. Calibrating at temperature extremes</p>

<p>9.12. “Chatter ball” calibration</p>

<p>9.13. Gravity calibrating an accelerometer</p>

<p>9.14. Hammer calibrating an accelerometer</p>

<p>9.15. Measuring transverse sensitivity</p>

<p>9.16. Shaker calibrating a force sensor</p>

<p>9.17. Gravity calibrating a force sensor</p>

<p>9.18. Hammer calibrating a force sensor</p>

<p>9.19. Microphone calibration by pistonphone</p>

<p>9.20. Comparison calibrating a microphone</p>

<p>9.21. Calibrate how often? </p>