dB Magnitude/ deg Phase to Real /Imaginary components

[ProfAlex]

Hello All,

I am developing a VI to process force and acceleration data acquired via a NI 9233 USB card to Frequency Response Functions, display as Bode and  then export this data to a SDRC Universal type 58 File....

This will support the Dynamic Vib and Modal Analysis undergrad teaching Lab being set up at the University of Central Florida in Orlando.

Using LV 8.2 and Sound and Vib Toolkit 5.0.

The only piece I cannot seem to find is a VI which will convert the Mag/Phase components from the FRF VI to Real/Imaginary as required by the UFF58  Export VI..   The real time display is using the FRF Mag/Phase (Bode) VI, I wish to then pass the averaged data for Re/Im conversion.

There is a Polar to Real/Imag VI but I have been unable to set up the correct data input formats for this as it needs Magnitude in amplitude rather than dB,

and  phase in Radians rather than Degrees..

I found  VIs for SVFA Unit Conversion ( dB to Linear ) and SVFA  Phase Unit Conversion (degrees to radians) to condition the data prior to the Polar to R/I VI, but am unable to satisfy the requirements of these . The VI runs, but I get no output from then into the UFF58 exporter.

I have done major searches, but not found a solution.

Thanks for your assistance:

I have 10+ years experience with Matlab, but only 3 weeks use with  LabView. Some simple tasks seem the most difficult in LV.

[dsb@NI]

Please try the attached VIs and let me know how they work for you. I recommend that you compute the Real and Imaginary components of the FRFs and then convert to Mag and Phase as needed for display. If you compute Mag and Phase and then convert to Real and Imaginary, the application has to perform an extra conversion from dB to linear scale in order to write to UFF. What program and analyses do you perform on the FRFs after you have written them to UFF58? Contact me at doug.bendele@ni.com if you need VIs that will operate on multiple channels.