Using Simcenter Testlab Time Signal Calculator? Here are some tips for you!
The Simcenter Testlab Time Signal Calculator (formerly LMS Test.Lab Time Signal Calculator) is loaded with functions to condition and perform calculations on time files.
Operations include filtering, integration, envelopes, rosette, math, logic operations, and more!
To turn it on, choose “Tools -> Add-ins -> Time Signal Calculator” (Picture 1). If using token licensing, this will check out 26 tokens.
Go to the “Time Data Selection” workbook and load up some time history data (Picture 2):
The time data is now available for processing. Each channel is listed under Data Set as shown as Picture 3.
Note the following about the time data list:
Formulas can be entered in the Time Signal Calculator to manipulate data in the list (Picture 4).
When creating formulas in the Time Signal Calculator, there are some key fields that can be filled out:
Once channels are loaded, notice that they are assigned identifications, for example, CH1, CH3, etc. CH is short for Channel.
The math operations ( +, -, /, * ) can be used with these "CH" identifications (Picture 5).
When doing these operations, it is not necessary to use the assigned channel identification. Instead, one can use the Point Identification:
The desired engineering unit can be assigned to the result of any math operation. Use the bracket signs to assign the unit, for example [g]
To ensure the data is handled properly, the assigned unit needs to be a valid unit that exists in the Simcenter Testlab Unit system. If you are not certain what units are valid, go to “Start -> Programs -> Configuration and Unit System…” to get the available list. Note that the units are case-sensitive (Picture 6).
There will be a warning if the unit specified is not available/valid, and the status on the formula will be colored red.
Create additional cells for formula using F key with a yellow star. There is no limit to the number of formulas. You can also delete the formulas using the F key with a red X.
To save formula sets and recall them for later, use the buttons.
In addition to math functions, many other operations can be performed on time data. To access the other functions, highlight the cell for which to create the functions and press the button with “f(x)” showing on it (Picture 7).
A list of functions appears. The left side of the menu are categories for the functions, while the right side is the list of individual functions as shown in Picture 8.
As an example, to create a high pass filter, select the FILTER_HP function (Picture 9).
For a filter function, the following can be filled in:
Information about these fields are found in the the knowledge base article: FIR versus IIR Filtering.
Press “OK” when finished.
To perform the filtering operation, press the “Calculate” button to perform all functions in the list. “Calculate Selected” can be used to perform only the highlighted function.
More Advanced Functions
Other popular processing functions include:
Multiple Functions - CHX
Sometimes the same operation may need to be performed on multiple channels. However, it is not necessary to create 20 separate FILTER_HP functions to filter 20 channels. This can be done in one step as shown in Picture 10.
Here is how:
Note that the “Repeat for…” field may require using the slider bar in the lower left corner to scroll over to see the field. It may not be visible by default.
Using CHX with an Offset
CHX can be used with an offset on the variable X. For example, for X equal to 1:
CHX3 means that 3 is added to the current value of X. This could be used to do math between two triaxial accelerometers as shown in Picture 11.
In the example shown in Picture 11, the X direction of Accel1 will be subtracted from the X direction of Accel2. The same will be done for the Y and Z directions because of the "Repeat for..." being set to "1:3".
Expand CHX to Individual Formulas
After creating a formula using the CHX convention, it can be expanded into individual formula rows using the expand button.
This can be convenient for naming the results of individual calculations as shown in Picture 12.
When a single formula is used with the CHX convention, the Point Ids are generated automatically. The user has no control of the names. The expand button allows individual Point Ids to be entered.
Temporary Data Storage
Sometimes an intermediate calculation is performed enroute to a final calculation. For example, a high pass filter might be applied to data before integrating as shown in Picture 13.
Instead of using a destination id of CH3 to store the high pass filtered data, the destination id is given as VAR3. This stores the data on a temporary basis. It will not be permanently stored and take up disk space.
The data that is calculated in VAR3 can be referenced by other commands, even though it is not permanently stored.
Simcenter Testlab Processing Tips
Simcenter Testlab Display tips: