Define Signal Dialog Box

Defines or edits a limit signal for the Limit Test step. In the Configuration page of the Limit Test step, click the Define Upper Limit, Define Lower Limit, or Define Single Limit buttons to display this dialog box.

You can specify the signal using a series of data points that represent the x, time or frequency, and y coordinates for the corner points of your signal. The resulting limit signal is composed of a series of straight line segments that connect these points.

This dialog box includes the following components:

• Data Points—Displays the values you enter to create the signal. You can enter values directly in the cells of the table or use the options in the Rescale limit section to create a signal.
• Insert—Adds a new row to the Data Points table.
• Delete—Removes the values in the Data Points table.
• Rescale limit—Contains the following options for defining values:
  • New min. Time—Specifies the minimum value for the x-axis scale.
  • New max. Time—Specifies the maximum value for the x-axis scale.
  • New min. Ampl.—Specifies the minimum value for the y-axis scale.
  • New max. Ampl.—Specifies the maximum value for the y-axis scale.
• Load Data—Prompts you to select a .lvm file that includes signal data you want to use to define a signal.
• Save Data—Saves the data you configured in Data Points to a .lvm file.
• Defined Limit—Displays the signal you define and a reference signal if you place a checkmark in the Show input signal checkbox.
• Show input signal—Displays a reference signal in the Defined Limit graph.
• Show interpolated values—Enables linear averaging and displays the interpolated values on the Defined Upper Limit or Defined Lower Limit graph.
• Frequency axis is logarithmic—Sets the graph frequency axis to logarithmic and, when the Limits source is User Defined Signals, computes the limit values between the definition points so the resulting segment appears as a straight line in a logarithmic frequency representation. For example, you can use this to create asymptotic limits fitting filter roll-off in decibels per decade. This option is only available if the input is a frequency-domain signal.

Note  If the input is a frequency-domain signal, place a checkmark in the Frequency axis is logarithmic checkbox to display your signal in a logarithmic frequency scale and create a limit signal connecting the corner points so that they appear as line segments in a logarithmic representation. This is useful if you want to define limits that follow an asymptotic frequency roll-off represented in decibel/decade.

Use this dialog box to define data values for a limit test.