Automatic Data Processing in APEX DX Dynamic Data Analysis Software
By: Sam Nichol
In our product APEX DX, there are two workspaces created to streamline your dynamic data analysis process. The first is the designer tab where you can create an analysis design to process your data. The second workspace is called the viewer tab, where you can view your data with the analysis performed in the designer tab using a wide range of dynamically interactive plots. In this blog post, we are going to talk about the simplest way to view and interrogate data from a test, and what elements are automatically created when a file is processed to better understand the building blocks of DX.
When opening DX, the first thing that you are met with is the designer workspace. It consists of a canvas upon which you can place combinations of our 22 designer “elements” which can be used to create all kinds of processing flows to perform simple or complex dynamic data analysis. Designs are graphical, intuitive, easily created and reusable. Designs can be created manually, from supplied templates, saved designs, or by simply dragging a dynamic data file onto the canvas. We will explore this last method because it is amazingly simple and really powerful. All the other methods are easily understood once this basic concept is demonstrated.
Dragging and dropping a dynamic data file on the design canvas automatically creates a very simple design that will be used to automatically process the file and allow you to view the data. The automatically created design consists of five elements; a Signals element, a Parameters element, an FFT element, a Peaks element and a Scope.
Pictured: A real data file (321 MB) with 40 signals and 2 parameters is automatically processed by dragging the file onto the viewer.
The Signals Element tells DX what signals in the dynamic data file to process. It’s a powerful tool that allows users to process all, or a subset of signal from the file without having to create sub-files. There are two types a Signals elements; “Signals” and “Signals*. Using the Signals element allows the user to select individual signal names to process. Signal* does the same thing, but allows the user to take advantage of naming patterns in the signal name. This is done by using wildcards and regular expressions. Both elements provide settings for time domain processing that let you alter the signal type (AC, DC, AC1xInt, AC2xInt, AC Diff, IRIG), Coefficient, EU Scalar and Units. When automatically processing a file, DX will create a standard Signals element and populate it with the signal names of all the signals in the file and default time domain processing settings. You can edit this afterward to limit what signals are processed the next time or to adjust time domain processing options. Notice that this one element type has multiple functions. Some competing products make the user add separate elements for each of these functions which can clutter the workspace. Our approach simplifies the overall readability of the process while preserving sophisticated functionality.
Pictured: Easily add and remove signals that want to process or leave out of the process chain.
The Parameters element is similar to the Signals element in that it selects which parameters are included in the analysis. Parameters are measurements made at lower sample rates, like pressure, temperature, speed, and the like, which are sometimes available in a dynamic data file. Our offline data acquisition product, APEX-DX, easily merges low and high speed data together so users can perform analyses to understand how dynamic responses are affected by various parameters, like speed or pressure. Not all dynamic data files contain parameters, so if they aren’t present, DX may not automatically create a Parameters element.
Like the Signals Elements, the Parameters elements also can consist of a sensor name list, or can use wild cards and regular expressions to refine the list of data to be processed. Parameter settings include min and max value, Type (generic, speed (DC), speed (tach)), tach ratio, trigger threshold, average time and units. These latter settings can be used convert a tach pulse-train into speed value using powerful DX speed decoding algorithms.
The next basic element that is automatically created is the FFT Element – both the signals element and parameters element are automatically connected to it. When added to the design it runs an FFT algorithm on the signals. Available settings include Scaling (Peak, P2P, RMS), FFT Size (sometimes called ensemble size), FFT Overlap, and Window (Rectangular, Blackman Harris, Hamming, Hanning, Gaussian, Flat Top). As with the other elements, DX sets default settings for these properties which can later be edited for reprocessing, if desired.
The last processing element in the automatic file processing setup is the peaks element. This element performs spectral line interpolation to improve frequency and magnitude accuracy from the FFT. The FFT Element is automatically connected to it. Peaks provide additional spectral values beyond the normal spectral lines so your analysis is even more accurate. This element is not required (if you are only interested in the spectral line values), but is automatically created when you drag a file on the canvas. You can delete it later and reprocess, if desired. Available peaks element settings are Maximum Peaks, Peak Threshold, and frequency range – which can also be edited at any time.
Pictured: Available settings in the Peaks Element.
After all the elements have been connected, they are finally connected to a Scope element which basically tells DX to output the processed results to the view canvas. Scopes can be attached to various elements along the way. For example, you could add a Scope to output spectral line values from the FFT Element and another to the Peaks element to compare the output. When automatically processing a file, DX adds one Scope at the end of this simple process to provide output for viewing on the View Canvas.
Pictured: A demonstration of adding multiple scopes to a design for side-by-side viewing of FFT and Peaks Processed data.
One important thing to think about is that once the process is defined and the data file is processed (which is done automatically when you drag a dynamic data file on the design canvas), the processed results are ready for plotting in a large variety of ways – instantaneously. This give the user the ability to look at processed results and compare channels, create different kinds of plots, or otherwise interact with the processed results without having to define a plot in advance.
Pictured: Comparing the subtle differences between an FFT Element Scope (Top) and a Peaks Processed Scope (Bottom)
One last important feature to note – you can drag multiple files on the Designer canvas and process multiple files at the same time. This way you can easily compare any signal against any other signal from a group of files in a single work-session.
If you are interested in easily processing and viewing data, and would like to try out a free trial of DX, please contact our sales team at email@example.com