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Tip of the Month:
Portable Accelerometer Calibrator Validates Both Low and High Frequencies
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Even though accelerometer reference frequencies are at a single point (either 100 hz or 159.2 hz), it is beneficial to have a portable vibration calibrator with selectable excitation frequency. This allows users to validate both the low- and high-end of the frequency response ranges of most accelerometers, as well as their nominal calibration at reference frequency.
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Technical Exchanges
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By Bob Metz, PCB Piezotronics
June 17, 2015
Buffalo, NY
June 22-25, 2015
Grand Rapids, MI
July 19-23, 2015
Grapevine, TX
By The Modal Shop, Inc.
July 24, 2015
Dallas, TX
August 3-6, 2015
Austin, TX
August 9-12, 2015
San Francisco, CA
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Quick Links
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ISO TC 108 - Mechanical vibration, shock and condition monitoring
ISO TC 108/SC 3 - Use and calibration of vibration and shock measuring instruments
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Previous Newsletters
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Why is 100 Hz or 159.2 Hz the Reference Frequency?; Sound Power Basics
ICP vs Charge Mode Sensors; Percent Difference vs Deviation in Accelerometer Calibration
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Select Newsletter Articles
by Topic
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Accelerometer Calibration from a
Risk Management Perspective
By Mike Dillon, Calibration Product Manager
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Recently, I was asked the question: "I dropped
my accelerometer from a tabletop to a concrete floor. What is the risk of damage?"
Since the question was asked in terms of risk, I gave the rather long answer I give here in terms of risk management, rather than a short answer of "high or low."
When we think of risk, we think of it first as risk assessment and then risk management.
Define the Risk
First we define what the hypothetical risk event is: For this case, we will say - "My accelerometer was damaged when it fell from the table, and the damage is such that it will affect the interpretation of the data I collect with it..."
Click to read full article
modalshop.com/calibration.asp?ID=1054
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Microphone Calibration Part 1:
The Insert Voltage Technique
By Bryan Butsch, Engineer
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In this month's article, we will discuss  microphone calibration using the insert voltage technique to calculate the open circuit sensitivity of a precision condenser microphone. Let us first define open circuit sensitivity before explaining how to calculate it. The open circuit voltage of a microphone, according to IEC 1094-1, is the unloaded alternating voltage as measured at the electrical output terminals of the microphone. The open circuit sensitivity of a microphone is the ratio of the microphone's open circuit voltage to the sound pressure level applied to the microphone by a sound source. Because it is impossible to measure the open circuit voltage from a microphone directly at its electrical terminals, the insert voltage technique (as described in section 5.3 of IEC 1094-2) must be applied...
modalshop.com/calibration.asp?ID=1055
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Blast from the Past:
The Devil is in the Accelerometer
Calibration Details
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 When seeking the best uncertainties and most consistent daily verification and operation of your accelerometer calibration system, it pays to know your sensor details. The key to accelerometer calibration is ensuring that everything starts from a "flat line." This means no relative motion between Reference Accelerometer and Sensor-Under-Test, as well as no local resonances and...
modalshop.com/calibration.asp?ID=653
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Thanks for joining us for another issue of "Dynamic Sensors & Calibration Tips". As always, please speak up and let us know what you like. We appreciate all feedback: positive, critical or otherwise. Take care!
Sincerely,
 Michael J. Lally A PCB Group Company |
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