2.4.20. Tracking Plots

Tracking Plots display the collected spectral peak responses in one or more frequency bands from one or more channels. These plots:

  • Require the selection of the following items on the Plot Creation tab before adding them to the plot grid:

    • One or more primary data channels.
    • One optional X axis reference parameter or channel stat.
    • One phase reference channel or speed parameter.

  • Do not extend the Plot Menu with additional choices.

  • Add an extra page to the Plot Setup dialog with tracking plot specific settings.

  • Provide no additional user interaction mechanisms beyond the ‘standard’ ones described in the Plot Interactions section.

../_images/ptypetracking-f55dae38.png

Example Tracking Plot

Tracking plots collect and display spectral peak responses collected in user defined frequency bands. Three collection methods are supported:

  • DFT Order Tracking: This method requires that a speed parameter is used as the plot’s X axis. The plot will collect time domain data samples between two trigger pulses of the speed parameter. The collected data samples will then be analyzed using variable length DFT (Discrete Fourier Transform) processing to extract the response at the desired order. Response magnitudes and phases can be collected this way.
  • FFT Order Tracking: This method also requires that a speed parameter is used as the plot’s X axis. The plot will collect the largest FFT responses from each processed data block that match the specified order and tolerance interval. Response magnitudes and phases can be collected this way.
  • FFT Band Tracking: This method collects peak responses that match a user defined fixed nominal frequency and tolerance range. Response magnitudes and actual frequencies can be collected this way.

Collected response curves can be further refined using various sorting and filtering options.

../_images/ptypetracking-c867e32f.png

Example Tracking Plot Setup Page

Tracking plots have their own specific Plot Setup dialog page, The top part of this panel allows the definition of the collected tracking curves. For each channel a user defined number of tracking curves can be added. The collection method, nominal value, tolerance band and threshold of each curve is individually adjustable.

The bottom half of the panel controls global options that apply to each collected tracking curve.

  • Trace Sorting: Controls whether the plot collects tracking curve points in the order of arrival or sorted. In the second case the points can be filtered to produce a “smoother” tracking curve.
  • Trace Points: Optionally limit the maximum number of points for each tracking curve. This is done by finding the two points with the nearest X values and replacing them with a single point whose X and T values are the averages of the replaced ones.
  • Filter Interval: This is used for sorted and filtered tracking curves. Each newly added curve point’s Y value is replaced with the average of itself and all already existing points that fall within the specified parameter distance range.
  • Max Points: This is the maximum point used when trace size limiting is enabled.