NI Labview, SignalExpress, Power Spectrum (Spectra)

[dho]

the top plot is in time domain the signal from an accelerometer. the bottom plot is in frequency domain.
i do not understand the unit of the power, (dB ref 1.0E+0 V/sqrt (Hz).
can anyone shine me some light?
thanks.

 

[GregLocock]

The answer in your other thread was correct. you need to enter a calibration for your accelerometer, telling the ADC how many g a given 1V signal represents.

Cheers

Greg Locock


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[dho]

would you please explain it "mathematically" ?
thanks.

 

[IRstuff]

Please refrain from double posting. Your question was already answered: thread31-384452

TTFN
faq731-376

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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com:

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[GregLocock]

dB=20*log10(psd in engineering units per sqrt(Hz)/1.0)

The slight oddity is they have use V/sqrt(Hz) rather than V^2/Hz, but that is not uncommon, and the relationship is obvious.

I suggest you read and understand the section on engineering units and dB in this

https://www.google.com.au/url?sa=t&...5AtK3c-4w_dlPdM51zfcNIQ&bvm=bv.90491159,d.dGY

Cheers

Greg Locock


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[GregLocock]

Sorry that equation assumes you want dBref = 1 engineering unit, if you wanted 0 dB to be at any other reference replace the 1.0 by that figure

Cheers

Greg Locock


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