Need VI to determine Q and Resonant Frequency

[sammy346]

The signal captured by the digitizer is approximately a decaying sinusoid, i.e. of thre form y = A(e^-x) sin(x) for x>0.

From the data points obtained, I wish to determine the Resonant frequency and Q (quality factor) from a measurement.

I have not been able to find a VI/VI's that can do this yet.

1. Is there one available.

2. If not... Do I need to implement a custom'curve fitting' type algorithmto determine these values instead.

Some direction as to where to proceed would be much appreciated.

Thanks in advance.

TTFN

[Dan_K]

Hello Sammy,

There isn't a specific function that will perform the operation you are looking for. I would recommend first finding the frequency and phase shift of the sin wave component and divide it out. You could find these components by comparing peaks to find the wavelength. With this information alone you can find the frequency of the sine wave component. Next by comparing the difference between the wavelength and the beginning of the waveform you can find the phase.

After dividing out the sine wave component you can use exponential curve fitting to get the rest of your parameters.