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LMS Test.LAB: Acoustic order tracking measurement with a weighting


Dear all,


I had measured an acoustic order tracking. Then I can create a picture with the acoustic order. In this picture I can calculate on the y-axis under processing a weighting e.g. like A. When I want the same with the overall level of the acoustic channel then I get the message from the program: Weighting can only be applied on frequency spectra.


My question: Why can I calculate only the orders not the the overall level with a weighting?


The weighting with an overall level I can only create with the a measurement under Online Processing. It is not possible, when I forgot a weighting e.g. A at the measurement with an overall level, to make a subsequent calculation in a picture.


Why not?


The only way to calculate it later, is the detour via the Time Data Processing.


Is there an easier way ?


Thank you for your reply



Re: LMS Test.LAB: Acoustic order tracking measurement with a weighting

Siemens Genius Siemens Genius
Siemens Genius

Hi Kurt - As an overall level function is a calculation of the total energy in the frequency range measured, the underlying frequency content is lost.  Therefore, any weighting desired can no longer be applied, as of course the curves for A-, B-, etc. are frequency dependant.  As documented in the online help, the Common Overall Level is described as:


This function is based on the frequency domain computation of the rms of the block being acquired. The rms (root mean square) is computed by squaring values over the frequency range. Then the square root of the mean is taken. So, for a frequency spectrum block, the OA level is given by:

OA Level.jpg



I'll ask around to see if anyone has suggestions for weighting overall level curves in an easier fashion that recalculating in Time Data Processing.

Re: LMS Test.LAB: Acoustic order tracking measurement with a weighting

Siemens Phenom Siemens Phenom
Siemens Phenom

In addition to Jason's reply of reprocessing the throughput data on the Time Data Processing worksheet, you can also calcualte the A weighted Overall Level on the Post Processing worksheet that is available in Signature Testing Standard or Advanced or available via the Signature Data Post-Processing Add in.  Highlight the waterfall data and then calculate the overall level after setting the frequency range Min and Max via the "Set as processing parameter" button.  The overall level will be stored in the active section in a Processing folder as shown below.