Forum: help

RE: frequency analysis [ Reply ]
By: Abraham Otero on 2024-07-22 15:02

Different packages or tools oftewn produce different results for HRV indexes due to variations in implementation details and/or the usage of different default parameters. Besides the lack of standardization in the values of the parameters (for example, frequency band ranges), implementation details also affect the results. Some examples are how exactly ectopic beats are filtered, the algorithm used to interpolate the RR intervals to obtain a time series of constant sampling frequency (linear, quadratic, cubic, and cubic spline functions...), the interpolation freuquecy ( 2, 4, 8... Hz), how to remove the DC component (from all the RR series, from each window...), the window type (Hamming, Welch, Flattop,...), window size and window overlap used in the Fast Fourier Transform, or the mother wavelet used. With RHEV being open source, everyone can inspect those details. and since it's free, everyone can reproduce the results obtained with it.

frequency analysis [ Reply ]
By: paolo maccallini on 2024-07-22 13:15

[forum:49946]

Good morning,

I am a RHRV user with an issue with the frequency analysis of five-minute recordings.

I noted that HF and LF from RHRV analysis are substantially lower than expected, based on the literature on five-minute recordings. Comparing the output of RHRV with the calculations made on the same RR series by a common APP, I find the same results for the time domain analysis and LF/HF, but LF and HF from RHRV are about 1/5 of the output of the APP.

I followed what was indicated in the Springer book and other sources:

hrv.data<-BuildNIHR(hrv.data)
hrv.data<-FilterNIHR(hrv.data)
hrv.data<-InterpolateNIHR(hrv.data,freqhr=4)
hrv.data<-CreateFreqAnalysis(hrv.data)
hrv.data<-CalculatePowerBand(hrv.data,indexFreqAnalysis=1,LFmin=0.05, LFmax=0.15,HFmin=0.15,HFmax=0.4,size=300,shift=30,type="fourier")

Any suggestion is welcome. Thank you!