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Spectral Based Diagnostics: FFTDiag

Whatever the machine you deal with, you have to take care about its noise and vibration related to machine health and health assessment. OROS provides instruments with cepstrum, envelope demodulation, FRF, ORF, correlation and indicators dedicated to diagnostics and predictive maintenance of industrial machinery.



A complete toolset dedicated to machinery diagnostics: rotating machine trains, transmissions, gears and roller bearings


  • ShaftView
  • Kinematics’ markers
  • Levels & profiles 15
  • Cepstrum
  • Envelope demodulation

Time Domain Analysis

The TDA software module extracts the whole significance of signals in the time domain. It provides both overview and detailed statistical levels extraction. This approach immediately gives the nature and quality of acquired signals.
It allows surveying various tests and machine operations with the user define observation duration (time base) which range from 1/3rd of a second to an entire week.  This module can run independently from the run/stop, for continuous monitoring.

Time view

The Time View shows the signal envelope used for control and shocks identification. The statistics of the signal is available during the acquisition on any selected part of viewed signal.


The indicators profiles (DC, RMS, Pk, Pk-Pk, Crest factor skew and kurtosis) trace the main statistics of the signal with user define sampling and averaging. These profiles show the place and level of defect signatures. View meters are also available for indicators based supervision.

Spectral Diagnostics Toolset

The FFTDiag software module enriches your NVGate FFT with powerful computations, graphs, markers and signal indicators. It offers a complete tool set for diagnostic purpose on steady-state or low speed variation machines.

Time Domain

First statistical indicators are extracted from the trigger blocks. Such levels easily indicate offset (DC), shocks/clicks (crest factor), maximum excursion (Pk, Pk-Pk) and the true RMS.
The shaftview plots transducers time series along the shaft axis. This representation simplifies angular position understating showing the actual rotor, shaft, pulley and gears mechanics.
The envelope demodulation and periodic markers measure the periodicity of shocks form roller bearings and rotating parts.



The auto and cross-correlation are the right tools to identify a repeated or transmitted pattern in vibration or noise. Cross-correlation allows localizing the source position between 2 transducers.

Spectral Domain

The Cepstrum is a powerful tool which gathers each harmonics-set in one line. This technique enables the separation of multiple harmonic sets in one line each. Adapted to multi-shafts machines like gearboxes the Cepstrum makes such signatures clearer.
Based on an Excel description the kinematic marker helps in matching the significant frequencies with the machine parts.  Applying on spectra and cross functions (FRF, Coherence) this live marker is a must for rotating machineries diagnostics.

Order Diagnostics Toolset

The SOADiag software module provides an unrivalled investigation tool for measuring transmitted vibrations in rotating machineries for diagnostics and R&D purpose. Based on the OROS Synchronous Order Analysis, SOADiag supports super-fast speed variation machines like engines or motion motors.

These tools reject naturally the frequencies transmitted or generated (resonances) from the structure showing only shaft and transmission vibration.


Synchronous Statistics

These indicators (DC, RMS, Min, Max, Peak, Peak to peak and Crest-factor) are computed on the angular resampled trigger block. They compute the same number of revolutions whatever the RPM speed. They are useful to track the effects of variable speed and load.


Angular Domain

The shaftview plots time series along the shaft axis. Used on resampled signal the SOADiag shaftview shows high accuracy angular resolution which fits high variation cyclic machines like engine or piston compressors.



Similar to time domain correlation, the angular domain correlation support speed variation. They help identifying belt sliding for example.


Order Domain

The Copstrum™ reveals forced vibrations (≠resonances) from gears, strokes or bearing failure. It separates angular speed excitation from periodic shocks and clicks.
Order FRF so called ORF work like the spectra of angular cross correlation. This analysis shows the matching orders from 2 positions of a transmission. It helps identifying where torsional behavior damps or amplifies the cyclic speed variation.

OROS Software
R&D, Acceptance, Diagnostics

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