PSD with dB ON: is it 10*log(x) or log(x) ?

[student_1]

The Power Spectral Density (PSD) in LabView has an option of outputing dB values. I have found that it do this: 10*log(x). I just want to confirm that this is the case in all versions of LabView (I have 8.6) because If I am to use that program in different system I do not want different outputs that may be confusing.

[MegaWatts]

I see no indication in the detailed help that it has since changed in more recent versions of LabVIEW, but I can't personally verify that it will behave exactly the same across mutliple versions.

[student_1]

Is it 10 Log or 20 Log?

[billko]

10 for power, 20 for volts, I believe.  This is related to Ohm's Law for power equations.

[JÞB]

PSD assumes 50 Ohms default when converting Vrms^2 to dBm (deciBels relative to the milliWatt).  in all versions of LabVIEW 8.6 to date.  I doubt that will ever change

E=I*R

P=I*E

can't really be changed too much