7.2 Loading FRF data

A similar process is used for loading and plotting FRF data as with the operational data. The FRF Data card shows basic information for all imported data, such as name, status (if imported or loaded), type, size, and bandwidth.

Importing and loading data

SOURCE uses a “lazy loading” procedure that allows the user to import the data’s header information before actually loading all of the (potentially very large) data. Thus we have a two-step process to get the data into the workspace:

1. To import data, simply drag and drop the desired FRF data file(s) into the FRF Data card. While the data is being imported, the taskbar on the bottom will show you the progress of the operation. When the task is finished, “Idle” will appear in the task bar, and the file information will appear in the FRF Data card along with a gray status indicator to show that the data have not been loaded yet.
2. Next, the data have to be loaded. This is required each time you re-open your SOURCE project, as the data are not stored locally. To load the data, right click on the desired file and press “Load data”. When it is loaded, the status will turn from grey to green. It is also possible to unload data by right clicking on the file and selecting “Unload data”.

FRFs imported from DIRAC

If the FRF data are loaded from a DIRAC project (export) specifically, several FRF datasets may be available within a single file. The nomenclature used for the names of these datasets is the following:

• Measured ($$ \mathbf{{Y}_{uf}} $$): contains raw, untransformed FRF data that were obtained in the measurement;
• VP ($$ \mathbf{{Y}_{qm}} $$): contains data in which both forces and responses have been transformed to the Virtual Point(s);
• Force-VP ($$ \mathbf{{Y}_{um}} $$): contains data in which the forces have been transformed to the Virtual Point(s), while the responses are left unchanged. This dataset is most often used for in-situ blocked force TPA;
• User defined ($$ \mathbf{{Y}_{Custom}} $$): contains data with a custom selection of channels and reference channels, some of which may be transformed to the Virtual Point(s).

The types of data available in the specific file will depend on how the export settings were chosen in the DIRAC project.