FFT Spectrum Analyzer and Frequency Analyzer
- REAL-TIME FFT SPECTRUM ANALYSIS: The Dewesoft spectrum analyzer offers real-time FFT analysis on unlimited input channels.
- UNLIMITED INPUT CHANNELS: Our DAQ systems offer virtually unlimited input channel configurations and our DAQ software can perform FFT analysis on any or all of them at the same time.
- AVERAGING: Overall (averaged) FFT with linear, peak and exponential averaging or block-based calculation is available.
- ANY LINE RESOLUTION: Selectable line resolution up to 64.000 lines for most demanding tasks.
- CURSORS AND MARKERS: The FFT visual control can display values of the currently selected point with the markers. Available markers are a maximum marker, free marker, zoom marker, sideband marker, harmonic marker, RMS marker, delta marker and more.
- CURSOR VALUE ESTIMATE: Innovative window interpolation technique allows precise amplitude and frequency estimation.
- ADVANCED MATH: Auto spectrum, cross-spectrum, complex spectrum, waterfall spectrum, cepstrum (for bearing faults, speech processing), two-sided full FFT (for rotor whirl analysis), STFT (for non-stationary signals), envelope detection (for bearing fault analysis).
- LIFETIME FREE SOFTWARE UPGRADES AND SUPPORT: Our data acquisition systems come bundled with award-winning Dewesoft X data acquisition software. The software package is always evolving and new features are being added. We offer lifetime FREE software upgrades and technical support to all our users.
FFT Spectrum Analyzer Overview - Performance and Flexibility
Dewesoft FFT spectrum analyzer provides all main functions for spectral analysis with advanced averaging, selectable resolution (64.000 lines and more), or direct specification of the bandwidth (e.g. 0.01 Hz). Multiple channels can be displayed and analyzed in one FFT analyzer instrument for easy comparison.
It offers either real-time direct online frequency spectrum analysis during the measurement or offline frequency analysis on the stored data.
Check the video on the left to get a brief overview and see why our spectrum analyzer is the best performing and most flexible spectrum analyzer in the world.
Multipurpose Frequency Cursor Functions
The Dewesoft FFT analyzer allows setting multiple markers for automatic detection of different parameters. Our frequency analyzer offers the following markers:
- Free marker: free markers can be freely added. The marker shows us the frequency of the peak at which it stands and its amplitude.
- Maximum marker: the maximum marker finds the highest amplitude in the spectrum.
- RMS marker: RMS marker will sum up all the FFT lines in the selected band and calculates the RMS value.
- Sideband marker: the sideband marker monitors the modulated frequencies to the left and right from the selected centerline.
- Harmonic marker: the harmonic marker is a great help when identifying the fundamentals of the frequency.
- Damping marker: damping markers are best to use in modal testing when we want to find out how our transfer curve is damped. We select it when we are interested in the quality factor, damping ration or attenuation rate of a selected peak.
- Delta marker: shows the difference in channel values between two positions of the marker.
- Zoom marker: with zoom marker you can easily zoom into the selected region of a channel.
- Bearing cursor: identify the bearing frequencies (envelope detection)
FFT Analysis Settings
The DewesoftX FFT analyzer module allows several parameters to be set up before the calculation:
- Output channels - complex, amplitude, overall RMS
- Calculation type - block history or overall
- Windowing - Rectangular, Hanning, Hamming, Flattop, Triangle, Blackman, Exponent down, Transient
- Resolution - up to 64.000 lines (64k)
- Amplitude type - peak, peak-peak, RMS, PSD, Power
- DC cutoff - remove DC or low-frequency components
- Overlap - define the percentage of time signal that has already been calculated and it is used again for calculation
- Weighting - calculate the sound weighting in the frequency domain (A, B, C, D)
- Averaging type - linear, exponential, peak-hold
Bearing Fault Detection
Envelope detection is a procedure for the early detection of faults on ball bearings.
When a failure of the ball bearing occurs, it will produce ringing with a frequency that corresponds to its natural frequency. This ringing will repeat each time when a damaged part of the ball hits the ring or vice versa. We have to know also that the inner ring, outer ring, cage, and balls have different typical repeating frequencies depending on the geometry of the bearing and the rotational frequency.
Short-time Fourier Transform (STFT)
Short-time Fourier transform or shorter STFT is a well-known technique in signal processing to analyze non-stationary signals. STFT is segmenting the signal into narrow time intervals and takes the Fourier transform of each segment.
When the signal changes fast, you need a small time to calculate the frequency spectrum faster. But you still want better frequency resolution and here STFT comes in place (we get 16 times better frequency resolution for the same time frame.).
Full Spectrum transform (two-sided Fourier) changes complex input signal from time to complex frequency domain. The input signal should be in the form of complex synchronous data (re, im). Real and imaginary parts are usually gathered from two proximity probes installed in the X and Y direction. Traditional spectrum provides no information regarding the direction of motion of individual frequency components on rotating shafts and here is where full spectrum steps in.
Full-spectrum is used for signal modulation, signal demodulation, and rotor whirl analysis.
- the single value or block history
- overlap and DC cutoff
The cepstrum analysis calculation (also used to determine characteristics in speech analysis) helps to identify vibration signatures, such as frequencies in the gearbox and bearing analysis. Dewesoft provides mirror spectrum, low and high-frequency output.
- selectable block size
- overlap and averaging
The video on the right side shows Cepstrum math being used on a microphone input signal to determine the speaker's name.
Auto-spectrum and Cross-spectrum
Power spectral density (PSD) is the measure of the signal's power content versus frequency.
A PSD is typically used to characterize broadband random signals. The amplitude of the PSD is normalized by the spectral resolution.
Additional FFT Analysis Resources
Check the following links for additional resources and material regarding our FFT spectrum analysis solution: