Aquknowledge 4.1 gives HRV frequency domain statistics in units of "sec^2/Hz":
e.g. "Power in the high frequency band: 0.000374971 sec^2/Hz"
However, the recommended way to report frequency domain stats seems to be "msec^2":
"The measurement of VLF, LF, and HF power components is usually made in absolute values of power (milliseconds squared)". see: http://circ.ahajournals.org/content/93/5/1043.full
Can someone walk me through what I should do here?
Dear Niall, sec^2/hz = sec^2*sec = sec^3 = (1.0e+3*msec)^3 = 1.0e+9*msec^3
your power should be in watts or mv2/sec (with unitary load), usually sec2 is (103 msec)2 = 106 msec2
Hi NIall,
The msec^2/Hz represent the power spectral density of a signal (whatever HRV or other), in a band of "delta f" spectral resolution. The total power (msec^2) is obtained by integrating (sum) the power spectral density and you should obtain exactly the same power (msec^2) as in time domain by doing the (RMS(time signal))^2 (Root Mean Squares)^2 =Parceval theorem). Surprising the Biopac does that way.
Check out if you want CODESNA_HRV :
http://www.codesna.com/fr/produits/logiciel-danalyse-de-variabilite-cardiaque-codesna_hrv-telecharger/
Cheers,
Vasile
Hi Niall Mcloughlin,
Philip Cusimano, Technical Support form Biopac said me this:
If the data is in sec^2, multiply by 10^6.
If the data is in ms^2, multiply by 10^-6
Do you have found another way?
Best,
Hi Niall,
I hope that it will help you:
https://www.biopac.com/knowledge-base/unexpected-hrv-results/
Hi all, just wanted to say a belated thank you for your help with this issue. Much appreciated.
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