amplitude detection in signal which contains several frequencies

[mike_w]

Hello!

I have a problem that I hope someone could help me with. I am using a daqmx-9233, the signal I am measuring contains around 10-15 frequencies and I want to measure the amplitudes of thoose frequencies. The problem I discovered is that all solutions I have tried will scale the amplitudes. The easiet one seemd to be the power spectrum under signal express/analysis/frequency domain (I have also used just FFT and various amplitude detectors).

When I the power spectrum which is set to detect peak values it seems to be able to detect an amplitude correctly if there is only one frequency in the signal. Otherwise it seems as the amplitudes is divided by the number of frequency components in the signal, why is that and how can I do to get the real values?

I tried to connect a peak search to simply multiply with the number of peaks but it detected peaks around the actual peaks aswell, as for a peak at 100Hz the peak detector found peaks like on 99; 99.5;100; 101 (not the actual values but I hope you got the idea).

With the number of times I have banged my head in the wall I am soon to tunnel through:), I would greatly appriciate any help!

Yours Sincerely

Mikael

[tbd]

Hi Mikael,

      Did you find a solution?  If I understand you post, the "Extract Multiple Tone Information.vi" seems to do what you need(?)

Cheers.

[mike_w]

Hello tbd!

Tank you for your interest, well I did try the solution you suggested but it didn't work as I hoped. However the solution was more simple than i thought, I just took the fft of the signal and scaled it properly which gave me results I am happy with.

Best regards

Mikael