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In Historical graphs, there are often far too many lines or selections, making it difficult to troubleshoot an issue and narrow it down to the problem location. To simplify troubleshooting, this feature lets you quickly drill down through a large selection of modems to focus only on those that are changing by a significant amount.

For example, if a full fiber node is selected, you may see something like this:

This example displays lines criss-crossing over one another, which makes selection with the mouse difficult. If you try strumming across the graph, you may end up with this result:

However, you can also base a series selection on an overall change in value in the series. Each series is one line, one cable modem + channel combination. The change in value is the magnitude of the difference between the lowest and highest values over the period of time displayed in the graph, regardless of when these high and low values occurred. A series is selected when the change in value is greater than the value entered in either the change field or selected with the slider.

To select based on change in value
  1. Select an alarm in the Top Alarms table.
  2. Click the Historical tab.
  3. Drag one of the parameters to the graph view. In this example, Downstream SNR is used.
  4. Click the Display tab.
  5. In Selection Based on Change in Value, select a parameter from the drop-down. In this example, Downstream SNR is selected.

    Once a parameter is selected, the field to the right of the drop-down updates to indicate the units (for example, dB) that the change in value represents as well as choosing a value that is between the smallest change in value and the largest change in value.

    The resulting graph may look like this.

  6. Change the value in the right-hand field and press Enter; the slider position and the graph selection will update to reflect this change.

    You can adjust the slider to update the text field with the value that the position of the slider represents. The graph selections will also change accordingly. In the example below, a number higher than 0.65 was entered and the selections that meet this criteria are decreased.