The Observer: Modal Analysis for Any Structure Type!

The Observer Suite is your central structural and vibration monitoring platform, enabling efficient signal processing, modal analysis, and dynamic structural behavior visualization. Digitex designed it for structural engineers and researchers to streamline workflows—from measurement planning to modal parameter estimation—all in a clean, user-friendly, and intuitive interface.
However, our priority was optimizing and automating the software, critical for all structural health monitoring and civil engineering, including research activities. This way, you’ll be able to asses the long-term structural integrity of critical infrastructure like bridges, dams, high-rise buildings, and mines.
Our Observer enables multiple modal analysis methods, including three FDD (Frequency Domain Decomposition), two SSI (Stochastic Subspace Identification) methods, and the PLSCF method. Observer will easily and quickly transform your raw structural data into actionable insights and support your decision-making regarding the structure’s efficiency and people’s safety.
Stay tuned to find out how we optimized and automated our Observer OMA analysis software, enabling you to do modal analysis on any structure type!
Generate Your Geometry
Once you open the Observer software, you should navigate to the top bar and click “Model” and then “Initialization”. From there, you can import or create a new geometry for the structure you are analyzing and observing. The updated interface provides a powerful, intuitive toolkit to define your monitoring layout consisting of:
- Points: You can quickly place and configure individual sensor points and draw the instrumentation plan with precise control over coordinates and IDs.
- Lines: You can connect measurement points to reflect structural members or sensor pairings throughout the structure of interest.
- Surfaces: You can define the full 2D monitoring surfaces with mesh generation support for more advanced modal shapes and further analysis.
Each of these is configured in the Geometry Points, Geometry Lines, and Geometry Surfaces on the right of the Initialization window.
Once you define the points, lines, and surfaces, you’ll be able to integrate all elements seamlessly into your measurement configuration and feed it directly into the Observer OMA pipeline.
Lastly, the Observer OMA suite enables you to create a new geometry or adapt the existing one through the various features available.
Let’s dive deeper into how this is done!
Pre-OMA Configuration
Before diving into the different modal analysis methods, you should define your Observer setup by configuring the parameters and methods. This section of the workflow includes:
- Editing animation setup, such as Scale Factor, Magnification, and Auto Play in the “OMA General” settings.
- Enabling your preferred OMA method type (e.g., SSI, FDD, EFDD) in the “OMA Method Settings”. The Observer allows you to choose freely any of these methods or even combine them in a single analysis procedure.
- Adjusting the Filter Settings, such as Detrending, Decimation, Filter Type, and Filter Method, in the “OMA Filter Settings”.
- Setting up the Analysis Settings for Number of Frames, Number of Segments, Frequency Limit, Overlap, Block Rows, MAC Limit, and Resolution (NXSeg) in the “OMA Analysis Settings.”
- Lastly, you can configure the Point Size, Label Size, Display of Arrows & Labels, Surface Color & Transparency in the “OMA Geometry Settings”.
You can adjust all these by navigating to the “Geometry Properties” feature on the bottom left of your “Initialization of Operational Modal Analysis parameters and geometry” window.
This way, Digitex Systems provides you with an all-encompassing module for OMA analysis and user-friendly navigation through all the configuration parameters! We have optimized, unified, and simplified the process for structural health monitoring endeavors and user types.
Multi-Setup Configuration
The Observer Suite now supports multi-setup measurements, allowing you to analyze large structures using only a few sensors. No matter the number and setup of MEMS accelerometers, Observer keeps all setups organized, navigable, and easy to compare across frequency and mode shapes.
For the multi-setup configuration, you can add the reference sensor and all other sensors for the particular part or the whole structure.
Applying the Changes: Peak-Picking via SVD
Once your measurement and configuration are in place, the OMA Pre-Processing step begins. You can do this with a single action by clicking on the “Apply Changes” tab in your “Initialization” tab. The automated FDD OMA methodology will enable you to perform the following actions:
- The “Apply Changes” will enable you to initialize the post-processing analysis, calculate the OMA parameters, and generate the OMA Model.
- Once you generate the OMA Model, you can navigate to the “Analysis” bar and open the “OMA Calculation” window.
- Once you open the “OMA Calculation” window, you can choose the particular OMA method. In this case - the FDD methodology - you can choose between FDD, EFDD, and FSDD. However, keep in mind that you can’t implement the FSDD method in multiple-setup analysis. Once the Observer displays to you the SVD Diagram, you will be able to conduct the peak-picking procedure.
This step prepares your data for high-quality modal parameter extraction. You can use these features to determine the structure’s health with any of our systems and solutions.
Calculation: Frequency, Damping & Animation
The final stage is modal calculation and visualization. Observer now offers a refined engine for:
- Calculating natural frequencies and modal damping ratios
- Animating mode shapes with interactive 3D or wireframe overlays
- Exporting results in open formats for further processing or reporting
The updated modal viewer provides clear plots, exportable charts, and a smooth visual experience for identifying and communicating your results. You can do all this by just utilizing the peak-peaking method in the “OMA Calculation” window and clicking “Calculate.”
Digitex Systems’ Observer software also provides you with an in-depth analysis feature, displaying the following parameters for EFDD, for example:
- SodF Bell Function: You can now define the bell-shaped window applied to the time-domain signal during EFDD (Enhanced Frequency Domain Decomposition) for modal response isolation.
- Auto Correlation Function: You can also compute the autocorrelation of the inverse FFT signal for analysis of signal values and how they relate over time, aiding in the damping estimation.
- Portion For Fit – Specifies the auto-correlation function segment, which you can use for curve fitting during damping calculation.
- Frequency and Damping Fitting: You can perform curve fitting on the selected signal portion to extract the modal frequency and damping ratios.
Lastly but not least importantly, you can use the OMA calculation and analysis from the Observer software for further adjustments of the geometry and adjusting the frequency and damping.
For more info on our products and solutions, don’t hesitate to check our MEMS accelerometer, a weather station gateway, or a digitizing unit. You can implement any of these Digitex sensors to complement your modal analysis and crystallize your structural health monitoring efforts.