Performs the analysis of a narrow band component of the RR signal using Smoothed Pseudo Wigner-Ville time-frequency distribution and complex demodulation methods.
result = CDM_SPWVD_Analysis(RR,Vt,freq_sampling,frequency_bounds,filterlength [,options])
N
: The vector
of interbeat intervals of the R waves in the
electrocardiogram (ms).N
: The
tidal volume respiratory signal. its slowly varying
frequency gives the frequency reference.2
: the
frequency range of interest (in Hz).See the
Caution section for details.wfir("lp",195,[0.01 0],"hm",[0,0])
."RRA"
and
with the following fields:
N
, the time discretization associated
with the following signals.N
, the shifted RR signalN
, the shifted Vt signal or the empty
matrix.N
, the shifted band-pass filtered RR
signal.N
, the instaneous frequency of the
RR signal (in Hz) estimated by complex demodulation
method.N
, the instaneous frequency of the
RR signal (in Hz) estimated by smoothed pseudo
Wigner-Ville method.N
, the instaneous amplitude of the
RR signal estimated by complex demodulation method.N
, the instaneous amplitude of the
RR signal estimated by smoothed pseudo Wigner-Ville
method.N
, the evolution of the instaneous
phase shift between the RR
and
Vt
signals.N
, the instaneous power of the RR
signal.N
, the instaneous
dispersion of the RR signal.CDM_SPWVD_Analysis
Performs the analysis of a
narrow band component of the RR signal using both Complex
demodulation and Smoothed Pseudo Wigner-Ville time-frequency
distribution methods. It estimates the instaneous frequency, the
instanenous amplitude, the instaneous power and the instaneous
dispersion of the RR signal. It allows a simple comparison of
both methods.
Vt
is available or if one can insure stable
breathing in a narrow frequency band. In other cases SPWVD_Analysis is more
suitable. See the examples below.
The following demos illustrate cases of available Vt: Controlled breathing of control subject (RR & Vt), Controlled breathing of intensive care patient (RR & Vt), Free breathing of control subject (RR & Vt), Tilt test (RR & Vt), Apnea (RR & Vt). CDM and SPWVD instantaneous frequency and energy are superimposable.
The following demos illustrate cases of not
available Vt: Controlled breathing, control subject (RR), Handgrip
(RR), Ergocycle (RR). For the controlled breathing, CDM and SPWVD
instantaneous frequency and energy are superposable. But for
ergocycle, the breathing frequency increase needs a large
frequency band, [0.35 1.5] Hz
, with a central frequency fixed to
0.7 Hz
. In this case, CDM is not able to follow the real changes
in breathing, unlike SPWVD.
Vt
is available
d=read(cardiovascularpath()+"demos/DATA/decubitus_03",-1,4)'; //read the data freq_sampling=4; RR=d(1,:);//RR signal Vt=d(3,:);//Tidal Volume signal //narrow band filter filterlength=355; frequency_bounds=[0.25 1.9]; result=CDM_SPWVD_Analysis(RR,Vt,freq_sampling,frequency_bounds,filterlength); PlotSpectralAnalysis(result,["RR","Vt"],"CDM decubitus_03") // Draw results | ![]() | ![]() |
Produces:
Vt
is not available and breathing frequency is varying
d=read(cardiovascularpath()+"demos/DATA/cycle_spont",-1,3)'; //read the data freq_sampling=8; RR=d(1,:);//RR signal filterlength=355; frequency_bounds=[0.35 1.5]; f=scf(winsid()+1); res=CDM_SPWVD_Analysis(RR,0.7,freq_sampling,frequency_bounds,filterlength) PlotSpectralAnalysis(res,"RR","Ergocycle rrpa-8Hz") | ![]() | ![]() |
Produces:
One can observe poor CDM results compared to SPWVD. SPWVD is here able to follow the frequency variations.
Short-term control of the cardiovascular system: modelling and signal analysis Alessandro Monti , Claire Médigue , Michel Sorine. Rapport de recherche n° 4427 April 12, 2002
"Instantaneous parameter estimation in cardiovascular time series by harmonic and time-frequency analysis", Alessandro Monti , Claire Médigue , Mangin Laurence,IEEE Trans Biomed Eng. 2002 Dec;49(12 Pt 2):1547-56.
"Instantaneous envelope and phase extraction from real signals: Theory, implementation, and an application to EEG analysis". Periklis Y. Ktonasa and Nicola Papp