TMS Square sensor & calibration tips                                                                                      Your one-stop sound & vibration shop

Welcome to our next issue -
The goal of this monthly communication is to provide technical information and tips about the calibration and use of dynamic sensors in vibration, pressure and force.  The information is provided by the PCB Group of companies, as well as industry experts from research, government and academia.  Technical information is presented in a short, easy to read format and contains liberal links to further information should you desire a deeper dive into the technology.
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Tip of the Month

Importance of cable strain relief when calibrating...

A cable with proper strain relief is especially important when calibrating sensors at low frequencies.  At low frequencies, improperly attached cables can exert significant forces on the test sensor or even affect the electrical output of the sensor.  This can be easily remedied by using a little bit of putty to attach the cable to the side of the shaker.  The cable should be attached loose enough so that the shaker armature can still move freely, but tight enough that an excessive amount of cable does not vibrate with the test accelerometer.
Cable strain relief using putty
Quick Links
Newsletter Archive
May 2007 - Basics of Accelerometer Function; How Standards Link Together
June 2007 - Shear, Compression, Flexure; ISO 16063 Overview
July 2007 - Accelerometer Transduction Types (PE, PR, VC); Laser Primary Calibration
August 2007 - Quartz v Ceramic; Piggyback Calibration
September 2007 - between ICP and Charge, Shock calibration method
Behavior of Accelerometers...
...ideal, real world and what's the difference. 
T333B32 on Automobile FenderEver heard the old saying, "No one believes the results of a theoretical analysis except the analyst. And everyone believes the results of an experiment, except the experimentalist"?
In the test and measurement world this applies to the fact that vibration sensors are structures just like cars, computers, satellites and machinery that they are used to test.  This means that accelerometers undergo stress and show strain, they move, bend, deflect and often show signs of their real world behavior.  Test engineers and technicians need to understand the real world behavior of their measurement equipment to ensure that both valid data and valid results are produced.
Click here to learn more about ideal versus real world considerations in the behavior of accelerometers.
Primary versus Transfer Calibration...
...what it means and which is right for you 
Primary Laser CalibrationThe question often asked is, "When (or even why) do I need primary calibrations?"
Metrologists are also curious to know, "What does it cost?"
The short answer to "who needs it?", is that primary calibration is the standardized means to obtain the absolute minimum in uncertainty.  But to fully answer this question, one needs to first consider the reasons for calibration.  This month's discussion answers the question from the angle of uncertainties, costs and throughput rates
Click here for the answers to "who needs it?" and "how much does it cost?"...
As always, your satisfaction is at the pinnacle of our work.  If you have questions you would like answered, please contact us and we'll be glad to help out.  Your question may even be featured in a future month...
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Michael J. Lally
The Modal Shop
A PCB Group Company