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Vibration Testing
Calibration of Shakers &Vibration Transducers
The Minirator MR-PRO generates low frequency 1 - 10 Hzsine wave-files in 1 Hz steps. These test signals are typicallyrequired for low frequency vibration or seismic applications
such as driving a vibration source. This application note describes how to utilize the MR-PRO for calibration of vibration
applications.

Shaker calibration with Minirator
MR-PRO

The Minirator generates low distortion test signals from 1 to 10 Hz.
These signals are tailored for driving vibration shakers and for thecalibration of vibration transducers. Shakers and vibrations transducers are typically used in automotive, aviation and machineryindustry.

1. Calibration of vibration transducers
Vibrations sensors typically operate in the frequency range from
1 Hz to 20 kHz. In order to calibrate a vibration accelerometer its
sensitivity needs accurately be determined in mV/g or pC/g. Additionally the amplitude-frequency response shall be recorded andthe resulting flatness tolerance verified with the manufacturer
specifications.
The portable signal generator MR-PRO is the ideal test signal
source providing accurate sinusoidal signals from 1 Hz – 20 kHz
for the calibration of vibration transducers.

www.nti-audio.com

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Test configuration:
vibration
sensorpower supply& amplifier

shakerCalibration of vibration transducer with MR-PRO & XL2

The Minirator drives the shaker and a wideband voltmeter reads
the output signal of the vibration transducer (alternatively the NTi
Audio XL2 measures the vibration frequency and signal level).

How to measure the transducer sensitivity?
Adjust the MR-PRO output frequency to 159.2 Hz (=1000 rad/s,the typical calibration frequency).
• Set the MR-PRO output level according the technical specifications of the shaker and the vibration transducer, the resulting
shaker vibration is for example 10 g = 10x 9.81 m2/sec.
• Measure the vibration transducer output signal with the XL2(select the RMS/THD+N function).
• The sensitivity of vibration accelerometer is calculated assensitivity = measured voltage / 10g = x V/g• Verify the specified operation range of the shaker and vibration
sensor and measure the frequency response in this range. The
Minirator MR-PRO generates the following test signals:- for frequencies > 10 Hz to SINE signal- for frequencies < 10 Hz to WAVE
(load 1-10 Hz wav files into the internal MR-PRO memory)www.nti-audio.com

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2. Testing of vibration shakers
The operation verification of shakers is vice versa to the above described calibration guideline of vibrations transducers. A calibrated
transducer is utilized and mounted on the shaker. In this manner
the sensitivity and operation of the shaker can be verified.
Test configuration:
vibration
sensorpower supply& amplifier

shakerCalibration of shakers with MR-PRO & XL2

How to calibrate the shaker?
• Adjust the MR-PRO output frequency to 159.2 Hz (=1000rad/s, the typical calibration frequency).
• Set the MR-PRO output level according the technical specifications of the shaker and the vibration transducer, the resulting
shaker vibration is for example 10 g = 10x 9.81 m2/sec.
• Measure the output signal of the reference vibration transducer with the XL2 (select the RMS/THD+N function).
• The sensitivity of the reference vibration accelerometer islisted in the product specifications. The vibration frequency isshown in the XL2 display. The actual vibration level is calculated as• vibration level = measured voltage/(10x sensitivity) = x m/s^2• Verify the specified operation range of the shaker and vibration
sensor and measure the frequency response in this range. The
Minirator MR-PRO generates the following test signals:- for frequencies > 10 Hz to SINE signal- for frequencies < 10 Hz to WAVE
(load 1-10 Hz wav files into the internal MR-PRO memory)www.nti-audio.com

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The wave file set with sinusoidal subsonic frequencies 1 – 10 Hz
is available for download at NTi Audio website.

This application note has been developed in cooperation with theNTi Audio partner in Czech, Mr. Bedrich Votypka, Spectris. Many
thanks!

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