problems about the PSD vi

[klhjkg]

I have two problems.

In labviews there are 2 vi models "spectral measurement" and "FFT power spectral density" which both can calculate PSD of noise. Is there any difference between them or they are the same about PSD values.

I can apply them to measure PSD of noise whose output unit is dB directly.How can obtain the PSD whose unit is v/sqrt(Hz).

Thanks

[EBL]

I would use "FFT Power Spectral Density." The "Spectral Measurements" VI has a whole lot more stuff, most of which you might not need.

I've attached an example VI that creates a noise waveform with a sample rate of 1 MS/s and a noise density of 1 nV/rt(Hz). It calls the spectral density VI and displays the result. Notice that I had to take the square root of the data, because we want voltage spectral density but the VI returns power spectral density.

Hope this helps,
Ed

[klhjkg]

Thank you very much!

[Ancle]

Dear Sir,

I want to the same PSD function in LabVIEW 7.1(Base Package). What kind of the functions can I use? Thank you!

[MikeS81]

Hi Ancle,
it´s also available in LabView 7.1, but i´m not sure if it exists in the Base Package.

Mike