Plomb command and how I convert units!!

Hallo after applying the plomb command to a non-uniform sample and I got the PSD that I wanted! The thing I want to know is want are the units of the Power at the y axis? And how can I convert them to dB or at dBW/Hz?? Thanks!!

Answer 1

[Star Strider]

The documentation for the plomb function allows you to specify the output as 'psd', 'power' or 'normalized' (see the section on the spectrumtype (link) argument). Since the 'psd' option is the default, that will give you the result in units of db/Hz. If your original data are in Volts (amplitude) the output will be in terms of Watts (power). Choose the output option you want.

At least that is how I always understood power spectral density calculations.

[Panos Ale]

thank you very much! You are very helpful and always on time :)

[Star Strider]

As always, my pleasure!

[Panos Ale]

Another problem occured with the same command! When I use use the command plomp(x,ts) that get the pxx properly scaled! BUT when I type [pxx,f]=plomb(x,ts) I don't! For my project I need to know what are the units of pxx and how I convert them into Power! Thanks :)

[Star Strider]

My pleasure.

I believe I already mentioned that in my original Answer. See the documentation on the spectrumtype argument.

Remember that to convert power to dB, use ‘10*log10(power)’. This works for ‘power/Hz’ units as well, to convert them to ‘dBW/Hz’.

[Panos Ale]

Indeed you mentioned! Now I understand! Thanks for the clarifiction!

[Star Strider]

As always, my pleasure!