Displaying Data With Graphs
Graphs can display the following types of frequency response data in any combination for a given graph.
- A raw measurement as imported from disk
- A measurement filtered by the response of the filter channel to which it is associated
- The frequency response of a filter channel
- The frequency response of a measurement group. This is computed from the complex summation of the measurements in the group.
- The target curve (house curve), if any, assigned to a configuration.
To add a new graph, you can do either of the following:
- From the Graph menu, choose New Graph...
- In the Data View tab, right-click on the Graphs category node and choose New Graph... from the context menu.
This will launch a property sheet dialog having a tree display on its left side. The tree display contains category nodes which, when clicked, expand to show a list of property pages that can be activated to control various options for the new graph.
The Data category expands to show the four types of frequency response data sets you can add (Measurements, Filter Channels, Filtered Measurements, Measurement Groups and Target Curves). Selecting one of these subitems in the tree will cause an arrow icon to appear to its left, and the available data for that category will be shown in a property page on the right, with a checkbox for each one allowing persistent selection. Select the data you want to display. Pressing the Apply button will apply the changes without closing the property sheet, allowing experimentation with various settings.
The Format category allows for controlling various aspects affecting graph appearance (General, Axes and All Traces). The General property page allows for specifying the graph title and an option to hide it, whether or not a legend will be displayed, and the legend's location if visible. The Axes property page allows the properties of the x axis and left and right y axes to be set. This includes whether or not the axis is autoscaled, and the limits if manual scaling is used. It is suggested to start out with autoscaling of the y axis, then pressing the Apply button to see the results. Then switch to manual scaling if needed and adjust axis limits as desired, pressing Apply to test the changes each time. Grid visibility should be set to Automatic except for unusual cases. The All Traces property sheet controls how traces as a whole for this graph are displayed. You can display magnitude only, phase only, both, or elect to specify this individually for each trace. You can enable or disable phase unwrapping for the phase traces. Phase unwrapping presents the phase vs. frequency as a continuous curve without discontinuities near ±180°. When done modifying the graph properties, click the OK button to close the graph property sheet.
Appearance and behavior of individual traces of a graph are controlled via the Trace Properties property sheet. It can be launched in two ways.
- Right-click on the graph itself and choose Trace Properties... from the context menu.
- In the Meas View, locate the node of the graph, right-click on it and choose Trace Properties... from the context menu.
This property sheet allows selection of any trace by name and setting its magnitude and phase display offsets, whether or not you want the trace to update in real time as an optimization is running, and the trace color and line thickness.
A similar property sheet can be launched from the main menu by choosing Trace Properties... from the Graph menu. This property sheet differs from the one just discussed by allowing you to edit the traces of all defined graphs rather than just the selected one. This makes the Apply button less useful, as the desired graph may not be visible.
For more information about graphs, see Trying Out Graphs, A Second Look at Graphs, A Third Look at Graphs, and A Fourth Look at Graphs in the Tutorial.
Saving Graphs as PNG Files
A graph can be saved to disk as a PNG file without needing to use a screen capture program. To do so, ensure that the graph you want to save in this way is visible. The two ways to save a graph as PNG are:
- Right-click on the graph itself and choose Save as PNG File... from the context menu.
- From the main menu, choose Graph, Save as PNG File...
This will launch a dialog showing the existing dimensions of the graph's window in pixels. Change either the horzontal or vertical dimensions to change the pixel dimensions of the saved PNG file. The dimensions will be adjusted to retain the graph's aspect ratio. If you press OK, you'll be presented with a standard Save As dialog. Navigate to the desired directory, choose a name for the file to be saved, and press OK to save the file.