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Welcome to Issue #94    

 

Welcome to the 94th edition of our Dynamic Sensors & Calibration Tips newsletter!  That means we've been sharing education, tips and tricks for more than seven years now. You can see that we link to the most recent two issues in the left-hand column and include a "Blast from the Past" article. If you are a more recent member of our subscription list, please visit our newsletter web page for the full suite of almost 200 archived newsletter articles sorted by topic.
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Tip of the Month: 

Always Look for the Laser Etching on the Sensor

Sensors can easily be placed in the wrong boxes. When calibrating a sensor, always look for the laser etching on the sensor for the model number and serial number information. If the serial number cannot be read from the sensor, it should be sent back to the manufacturer for proper marking.

Technical Exchanges

August 3-6, 2015
Austin, TX

August 9-12, 2015
San Francisco, CA


Structural Measurements
August 12-14, 2015 

Modal Analysis
August 17-19, 2015
Cincinnati, OH

By The Modal Shop, Inc.
August 13, 2015
Phoenix, AZ

August 30-September 4, 2015
Prague, Czech Republic

October 5-8
Orlando, FL

October 20-22, 2015
Novi, MI

Quick Links
PTB 
ISO TC 108 - Mechanical vibration, shock and condition monitoring
ISO TC 108/SC 3 - Use and calibration of vibration and shock measuring instruments
ISO TC 108/SC 6 - Vibration and shock generating systems
Previous Newsletters
Small Arms Ammunition Manufacturer's Institute
(SAAMI) Discusses High Pressure Sensors and Calibration; Microphone Calibration Part II

Calibration from the Risk Management Perspective; Microphone Calibration Part I
Select Newsletter Articles 
by Topic
PCB Group Companies
How Does Relative Motion Affect My Calibration?
By Patrick Timmons, Calibration Systems Engineer

A frequent calibration question we receive here at The Modal Shop, Inc. is: "Should I bolt my shaker to a heavy table?" The difference in answer depends on which reference you are using with the shaker.  For back-to-back calibration, we typically answer "no;" for optical encoder calibrations we typically answer "yes." The reason we require bolting a shaker with an encoder displacement reference to a table or large mass is reference motion, often called relative motion... 


 

Click to read full article

modalshop.com/calibration.asp?ID=1060
Accelerometer Frequency Range: 
A Tale of Two Specs 
By Mike Dillon, Calibration Product Manager
In a previous article titled "Percent Difference vs Deviation in Calibration: What Do They Mean for Your Accelerometer Calibrations?," we reviewed the meaning of "percent deviation" when interpreting the frequency range specifications of accelerometers. The previous article included Figure 1 (below). 
This article will take a slightly deeper look at this and explain the accelerometer design choices that affect this specification.... 

modalshop.com/calibration.asp?ID=1064
Blast from the Past:
Why Proper Mounting is Essential to Calibration
A calibration laboratory was having a hard time calibrating a particular accelerometer. The sensor's specification according to the manufacturer's website, indicated a sensitivity value of 100 mV/g  (�10%) and a frequency response up to 6500 Hz (�10%). The initial calibration results at the reference frequency (100 Hz) were good and a sensitivity value of 99.97mV/g was measured, really close to the sensor's nominal sensitivity. Surprisingly enough, the sensor would repeatedly fail its frequency response calibration... 


modalshop.com/calibration.asp?ID=800
 

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,


Mike Lally signature
TMS 25 Years Michael J. Lally
The Modal Shop, Inc.
A PCB Group Company