Auto Threshold does not implement artifact rejection

Tech Note: TN0168
Product: OpenController
Version: All
Date Added: 2005-02-08

Issue

When OpenController's spike detection feature is implemented using the SortSpike component, auto thresholding only sets the minimum threshold for spike detection (green threshold line). Although the SortSpike component supports artifact rejection, implemented by setting a maximum threshold value, the auto threshold feature does not set this value and does not display the maximum threshold or artifact rejection marker (pink threshold line).

Workaround

To control the artifact rejection threshold and display the marker in the plot, you will need to set the value of the tag going into the second threshold line of the SortSpike component. One way to do this is to control the value using a slider.

Use the following steps to set the high threshold and display the threshold marker:

  1. In Controller, Click the Controls menu, click sliders/knobs, and click slider.

  2. Click the workspace to add a slider, then double-click the new control to open the properties dialog box.

  3. Click the browse button (...) next to Primary Target.

  4. Select Devices>Amp1>Scalars>bEA~ and click OK.

  5. Enter a Position Max of 0.005 and a Position Min of 0.

  6. Enter a Tick Precision of 4.

  7. Save the changes and run the project.

  8. Right-click the Scrolling Threshold plot (not the Snippet Sort Plot) and select Auto Threshold.

  9. The green threshold line will appear in both the scrolling threshold and snippet sort plots.

  10. Use the slider to set the threshold, bringing the second threshold (pink) into view in the snippet sort plot. Note that you cannot set the artifact rejection using the scrolling threshold plot.