How to Create and Import Target Curve Files

Created by Jake Bedard, Modified on Tue, 18 Jun 2024 at 03:00 PM by Casey Guli

How to Create and Import Target Curve Files


This article will walk you through creating both spectrum and transfer function target curves for use in Smaart, then importing them.


Please note that transfer function target curves are only available in measurement-capable editions of Smaart 9.4 and above as well as Smaart Data Modeler. For ease of reading, these will collectively be referred to as "Smaart/DM".


Creating Target Curves


To import a target curve file into Smaart, it must be a .crv file in either the correct spectrum or transfer function format. Below you will find guidelines and examples for both spectrum and transfer function target curve file creation from scratch using a text editor application.


Spectrum Target Curves


Spectrum target curve files are created with four heading lines, then two columns of data separated by a tab. The four heading lines are as follows:


  • Line:
    • The Line header represents the line thickness of the target curve after import, from 1 to 5. I recommend starting starting with a size 2, as this value can be changed in Smaart/DM later. 
  • Color:
    • The Color header represents the color of your target curve after import. It should be entered in HEX format. This can also be changed in Smaart/DM later.
  • Show:
    • The Show header represents if the target curve will be shown on the plot or not directly after import. I recommend a value of 1 (shown) here, but you can show and hide target curves using a checkbox in the target curve manager after import.
  • Band:
    • Spectrum target curves require their banding to be specified prior to being imported into Smaart. This is because spectrum target curves are locked to SPL values. When the banding setting is adjusted, so is the level at which the target curve is shown on the RTA plot. Please be sure to note what banding your data was set to on export if you are using exported data to create your target curve. Allowable values are 1, 3, 6, 12, 24 or 48 (full octave through 1/48-Octave). For example, a value of “3” means 1/3 octave banding. 
  • Type (Optional):
    • Spectrum target curves have an optional line for "Type" in the header. If the Type header is not present, files are assumed to be in spectrum format. 



Once the heading is complete, data can be added to the file in "Frequency    Decibel" format (separated by a [Tab] indentation). Target curves require a minimum of 2 data entries with both frequency and decibel information in each. An example spectrum target curve is shown below:





Transfer Function Target Curves


Transfer function target curves are created with six heading lines, then two columns for frequency and level. The six heading lines are as follows:


  • Type:
    • The Type header is what differentiates between Spectrum and Transfer Function target curves. When importing a transfer function target curve, please ensure that it has Type: TF
  • Line:
    • The Line header represents the line thickness of the target curve after import. I recommend starting starting with a size 2, as this value can be changed in Smaart/DM later. 
  • Color:
    • The Color header represents the color of your target curve after import. It should be entered in HEX format. This can also be changed in Smaart/DM later.
  • Show:
    • The Show header represents if the target curve will be shown on the plot or not directly after import. We recommend a value of 1 here so the target curve is automatically set to show but you can show and hide target curves using a checkbox in the target curve manager after import. Only values of 0 or 1 are accepted.
  • Tolerance:
    • The Tolerance header is set up for a future feature. For now, please put a value of 0 here.
  • Offset:
    • The Offset header determines the y offset for the target curve. Offset is normalized to 1kHz. 


Once the heading is complete, data can be added to the file in "Frequency    Magnitude" (dB) format (again separated by a [Tab] indentation). Target curves require a minimum of 2 data entries with both frequency and magnitude information in each. Transfer function target curves accept both positive and negative magnitude values.  An example excerpt of a transfer function target curve has been shown below: 






Creating TF Target Curves from a Trace


If you are looking to create a target curve from an already captured trace, please follow the steps below:

  1. Right click on the trace in question in Smaart's data bar and select Export to ASCII.
  2. Open the exported text file on your computer.
  3. Remove the Phase and Coherence columns of data. Ensure to keep the Frequency and Magnitude columns. 
    • Depending on your operating system and text editor of choice you can do this by holding down the Alt/Option key while clicking and dragging over the last two columns of data only. 
    • Once the columns are highlighted, use the delete key to remove them.
  4. Remove all headers at the top of the file.
  5. Add the new TF Target Curve header. An example has been provided below:




  6. Ensure there is one blank line between the bottom of the header and the start of data points.
  7. Save the file in .crv format. All target curves must be in .crv format.

Once saved as .crv, the file is ready to be imported into Smaart using the instructions in the Importing Target Curves section of this article


Importing Target Curves


Target curves are imported and managed from the Target Curve manager, accessible via via selecting "Target Curves" from the Options menu or by using the [ALT/OPT]+[X] hotkey. In the target curve manager, ensure that you are on the correct tab for your data type: "Spectrum" or "Transfer Function", then select the "Import" button. A window will appear with your operating system's file browser.


To display your Target Curve, ensure that its "Show" box is checked in the Target Curve Manager. Then, click the appropriate window (RTA for Spectrum Target Curves or Magnitude for TF Target Curves) and use the [X] hotkey.


Note: Target curves will not be visible if "No Banding" is selected on the plot.


Note that this menu also presents a visual interface to view and adjust the name, line thickness, offset, color, and offset of your target curves, as needed.





Sample Target Curves


Smaart includes with it a set of Spectrum target curves.

These include Min/Max/Target curves for both LFE (Low Frequency Effect) and X-curves, most commonly used for tuning cinema sound systems.




Here is what these look like on the RTA plot (toggled with the [X] hotkey):





Smaart v9.4 (including the current Beta) and later will also come with a set of sample TF target curves, pictured below:






Here is what these look like on the Magnitude plot:





 



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