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Traces


Traces are used to display the data that is stored in a dataset and the results of equations. There are several trace formats available for displaying data. Selecting various combinations of traces and plot types enable you to analyze simulation results in a variety of ways. Typical trace types are shown in the following table.

Trace Type

Description

Auto

A default trace type that is assigned to the data during simulation is automatically selected.

Bus

Displays bus or long-word data in octal, decimal, or hexadecimal format.

Linear

Displays data as a line. Points between measured data points are interpolated linearly to create a connected trace.

Scatter

Displays data as discrete points.

Spectral

Each data point is represented as an arrow that is perpendicular to the x-axis, the base of each arrow is on the x-axis, and each arrow points in the positive direction.

Histogram

Displays data as a histogram or bar chart, which is useful for statistical or yield analyses.

Digital

Displays data in a stair format, similar to a digital pulse. The trace steps up or down depending upon the relative position of two adjacent points.

Sampled

Similar to a spectral trace, except that vectors point in the positive and negative direction, and you can specify the type of symbol used on the ends of the vectors.

Density

Displays swept data in different colors. You can choose the colors and sequence for colors.

Because an automatic trace type is selected for data, you can view simulation results with little effort. If you want to analyze data in different ways, you can choose other formats or use equations to perform computations with data. For more information, refer to Equations.

Examples of traces are displayed below.

Inserting a Trace

You can add a trace as you create a new plot, or you can add a trace to an existing plot.
To insert a trace onto a plot:

  1. Double-click on an existing plot or create a new plot by selecting a plot type from the palette, positioning the pointer over the display area, and clicking the mouse.
  2. The Plot Traces & Attributes dialog box appears. Select the dataset containing the data from the Datasets and Equations drop down list. There are two other choices:
    • Select Equations at the end of the Datasets and Equations list to display the results of an equation on a plot. Equations are discussed in Equations.
    • Click the Manage Datasets button to set up an alias to display data in datasets that are not in the current project. For more information, refer to Dataset Aliasing.


  3. The variables in the dataset are listed under the dataset name. To add a variable to the plot, double-click on the variable or select the variable and click the Add button. The selected variables appear under the Traces list.
  4. A trace type for each selected variable is automatically chosen based on the type of data in the variable. You can select a different trace type or change trace attributes such as color.
  5. Click OK to dismiss the dialog box and insert the trace.

Selecting Independent and Dependent Variables

When Add is used to add data to a plot, the data is plotted with respect to the independent variable of a simulation. For example, transient simulations are a function of time, so any data from a transient simulation that is added to a plot using Add would be plotted with respect to time.

If you want to use an independent variable other than the default, use Add vs. to add data to a plot. Note that the dependent variable must be the same length or size as the independent variable when using Add vs. to add data to a plot. Not doing so will result in an invalid trace. You can use Add vs. with rectangular plots and with lists. For rectangular plots, you select the variables to be plotted along the x-axis and y-axis. For lists, the independent and dependent variables appear in two separate columns.

To compare two variables, do the following:

  1. To compare two variables on a new plot, choose Insert > Plot, position the pointer, and click or select a plot type from the palette. To compare two variables on an existing plot, double-click on the plot. The Plot Traces & Attributes dialog box appears.
  2. If this is a new plot, select a plot type.
  3. For new and existing plots, select the dependent variable from the list below Datasets and Equations and click Add vs.
  4. If you are using a rectangular plot and the dependent variable you selected is a complex number, the Complex Data dialog box will appear. Select how the data is to be handled and click OK.
  5. The Select Independent Variable dialog box appears. Select the independent variable from the list. It can be from a different dataset or equation. Click OK.
  6. If the independent variable you selected is a complex number, the Complex Data dialog box will appear. Select how the data is to be handled and click OK.
  7. Click OK to dismiss the Plot Traces & Attributes dialog box and display the trace on the plot.

Viewing Complex Data on a Rectangular Plot

The data from frequency-domain simulations, such as S-parameter or harmonic balance simulations, is stored in complex format. You can plot data from these simulations on rectangular plots, but you must scale the data to one of the following formats:

  • dB
  • dBm
  • Magnitude
  • Phase
  • Real
  • Imaginary

When you select the data and click Add or Add vs, if the data must be scaled the dialog box shown below will automatically appear. Select a format and click OK, and continue with the plot as usual.

When adding one trace at a time, additional checking is performed based on the simulation type of the selected trace. For example, if a trace is associated with a swept harmonic balance simulation is selected and you click the Add button, the following dialog will appear:

Note that this additional check is made only when a single trace is selected. When several traces are selected, the check for the type of data being plotted is more general.

Editing Traces


Trace options enable you to choose different trace formats and change trace attributes. If the trace is generated from an equation, you can also edit the equation.

The Trace Options dialog box is used to modify existing traces. Any changes made from this dialog box will only affect the currently selected trace. To change the options for all subsequent traces, refer to Setting Trace Preferences.

Note

Trace options for the chosen trace type are displayed automatically. If the trace options do not seem correct, click the Trace Type tab, click the button corresponding to the type of trace you want, then reselect the Trace Options tab.

To edit trace options:

  1. Double-click on the trace or select the trace and choose Edit > Item Options.
  2. The Trace Options dialog box appears.
  3. The Data Display enables you to change an existing trace's type. This is done by
    • Selecting the Trace Type tab.
    • Clicking the button above the desired trace type (see figure below).

      The suggested plot-trace combinations are:

      Plot Type

      Trace Types

      Rectangular and Stacked

      Any type

      Polar

      Linear and Scatter

      Smith Charts

      Linear and Scatter

      List

      None. Data is formatted from Plot Options

  4. You can keep the Auto trace type and still edit the attributes of the trace. Generally, the correct trace options will be displayed automatically. If you are not sure about the trace type or options, perform the following steps:
    • Click the Trace Options tab followed by the Auto tab.
    • Note the trace type shown in the Auto tab.
  5. The pattern, thickness, and color of a trace can be changed for all trace types except scatter. To modify a trace line, make the following selections:
    • Click the Trace Options tab followed by the tab that matches the trace type.
    • Select a line pattern from the Type list.
    • Select a line thickness by using the scroll bar or entering a value into the Points field.
    • Click the Color bar, select a new color, then click OK.
  6. In addition to editing the trace of a histogram, and you can also fill the histogram with a pattern. The color of the fill will be the same as the trace color. To fill a histogram:
    • Click the Trace Options tab followed by the Histogram tab.
    • Enable Use Fill Pattern.
    • Click the Pattern bar, select a fill pattern, then click OK.
  7. The type and number of symbols shown on a trace can be changed. Symbols are used with linear, scatter, and sampled traces to identify the data points that were measured during a simulation. To modify the frequency of symbols (for linear traces only), make the following selections:
    • Click the Trace Options tab followed by the tab that matches the trace type.
    • For linear traces, symbols can be displayed for some or all data points. Enable Auto Space Symbols (symbols are added for a subset of data points, selected to avoid overlap on the screen), or Place Symbols at all Data Points (symbols are added for all data points, regardless of overlap), or No Symbols.
    • Select a symbol from the Symbol Type list.
    • Click OK.
  8. The Data Display enables you to change the text properties and numeric format used in bus traces. This is done by clicking the Trace Options tab followed by the Bus tab and making the following selections:
    • Select a format for the data from the Format list. The choices are:
      Auto A default format is automatically chosen based on the data to be displayed.
      Dec Numbers are displayed in decimal (base 10).
      Hex Numbers are displayed in hexadecimal (base 16).
      Octal Numbers are displayed in octal (base 8).
      Binary Numbers are displayed in binary (base 2).
    • Select a font from the Font Type list.
    • Click the Text Color bar, select a color, then click OK.
  9. The Data Display trace labels are disabled by default. Trace labels are added to the display for linear and digital traces with subtraces (such as the curve tracer display) or plots with more than one independent variable along the x-axis.

    To turn on trace labels, do the following:
    • Click the Trace Options tab followed by the tab that matches the trace type.
    • Select Display Label.
  10. Data Display also provides options for displaying swept data (subtraces). These options are controlled by using the checkboxes in the Automatic Sequencing section of the Trace Options dialog box. For more information, refer to Setting Trace Preferences.
  11. When you have finished editing the trace, click the OK button to close the Trace Options dialog box and save the changes.

Deleting Traces

To remove a trace from a plot, do the following:

  1. To delete a single trace, single-click on the trace. For multiple traces, hold the Shift key down and single-click on each trace of interest.
  2. Press the Delete key or choose Edit > Delete.

Sometimes it is difficult to select a trace from a plot with multiple traces because the traces overlap. If you have trouble selecting a trace, use the steps listed below:

  1. Double-click on the plot.
  2. The Plot Traces & Attributes dialog box appears.
  3. Under Traces, select the variables used to generate the trace.
  4. Click Delete.
  5. Click OK to dismiss the dialog box and delete the trace.

Setting Trace Preferences

Trace preferences set the default trace properties and determine how traces will appear when inserted onto a plot.
Any changes made to the preferences will only affect subsequently created traces. To change an option for an existing trace, make the change using the Trace Options dialog box.
To save and reuse preference settings, you can create a preferences file that can be read by the data display. For more information on how to create and use such a file, refer to Setting Data Display Preferences.

To set trace preferences, use the following steps:

  1. Choose Options > Preferences.
  2. The Preference dialog box appears.
  3. Click the Main tab. Set the trace line and symbol preferences by making the following selections:
    • Select a line pattern from the Type list.
    • Select a line thickness by using the scroll bar or entering a value into the Points field.
  4. Click the Bus tab. Set the bus trace text and numbering preferences by using these steps:
    • Select a format for the data from the Format list. The choices are:
      Auto A default format is automatically chosen based on the data to be displayed.
      Dec Numbers are displayed in decimal (base 10).
      Hex Numbers are displayed in hexadecimal (base 16).
      Octal Numbers are displayed in octal (base 8).
      Binary Numbers are displayed in binary (base 2).
    • Select a font from the Font Type list.
    • Click the Text Color bar, select a color, then click OK.
  5. Click the Symbols tab. Set the label and symbol preferences by doing the following:
    • If you want to display labels, enable Display Label.
    • Select Display Arrowheads On Spectral Traces if you want arrowheads to appear on the measured data points on spectral traces.
    • If you want symbols to appear on the measured data points on linear traces, select Auto Space Symbols (symbols are added for a subset of data points, selected to avoid overlap on the screen), or Place Symbols at all Data Points (symbols are added for all data points, regardless of overlap). The default setting is No Symbols.
    • Select a symbol type from the Symbol Type list. This is the default symbol for linear, scatter, and sampled traces.
  6. Click the Histogram tab and set the histogram fill preferences by doing the following:
    • Enable Use Fill Pattern.
    • Click the Pattern bar, select a fill pattern, then click OK.
  7. Click the Parameter Sweeps tab and set the options that control the appearance of swept data (subtraces). The Automatic Sequencing options are:
    • Line Type - Overrides the default Line Type of the trace and automatically uses different line types for each sweep of the data.
    • Symbol Type - Overrides the default Symbol Type of the trace and automatically uses a different symbol for each sweep of the data.
    • Line Color - Overrides the default Line Color of the trace and automatically uses different colors for each sweep of the data.
      One or all of the Automatic Sequencing options described above can be enabled at any one time. If all three options are selected, the order in which they are sequenced is Line Type, Symbol Type and Line Color.

      Note

      The Automatic Sequencing options only apply to linear data. If you check more than one option, you will not see sequencing for the next option start until you have exhausted the previous option. There are many line and symbol types. Be aware that if you check all three options, trace color won't start to change until over a hundred subtraces exist, which is not a practical configuration.

  8. When you have finished setting preferences, click the OK button to close the Preference dialog box and save the changes.

History Traces

History traces enable you to perform a series of sequential simulations and have the resulting traces conveniently displayed in a single Data Display window.

You can turn trace history on, pause it, or turn it off completely. You can also have history mode enabled on some traces or plots, and disabled on others.

To enable history traces, select the plots or traces for which you want history traces gathered and then:

  • Choose History > On in the Data Display Window
    OR
  • Right-click and select History On from a popup menu

    Note

    If no plots and/or traces are pre-selected when you choose History > On in the Data Display window, history mode is enabled on all plots and traces in the window.

When history mode is enabled, an indicator appears at the top right hand corner of the plot and at the end of the axis label. The indicator on the plot is green when history is being gathered and red when history is paused. The indicator at the end of the axis label does not change color.

In history mode, the most recent data collected is represented by a thicker trace, and all previous traces become thinner.

To pause the gathering of trace history, choose History > Pause from the Data Display window menu.

To disable history traces, choose History > Off from the Data Display window menu. This command disables history mode and clears all existing history traces in the Data Display window.

You can change the default number of history traces displayed using the Preference dialog box. Choose Options > Preferences in the Data Display window, and use the History Traces area in the Main tab to change the number of traces.

Note

History traces are available to you as display only, and only for the duration of the session. Unlike the active trace, you cannot place markers on history traces, edit or save them.

Memory Traces

Memory Traces are primarily used in Advanced Design System tuning. For more information on using memory traces, refer to the Tuning section in the Advanced Design System " Tuning, Optimization, and Statistical Design " documentation.

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