Performs the analysis of a narrow band component of the RR signal using complex demodulation method.
results = CDM_Analysis(RR,Vt,freq_sampling,frequency_bounds,filterlength) results = CDM_Analysis(RR,freq,freq_sampling,frequency_bounds,filterlength)
a real vector of length N
: The vector
of re-sampled (see ResampleRR) interbeat
intervals of the R waves in the electrocardiogram (ms).
N
: The tidal
volume respiratory signal (sampled at the same frequency as
RR
. Its slowly varying frequency gives
the frequency reference. See the
Caution section for details.Vt
is not available. See the
Caution section for details.a real positive scalar, the sampling frequency (in Hz) of
the RR
and Vt
signals.
a real row vector of length 2
: the
frequency range of interest (in Hz). See the
Caution section for details.
"RRA"
with and
with the following fields:
N
, the time discretization associated
with the following signals.N
, the given RR
signalN
, the geiven Vt signal or the empty
matrix.N
, the shifted band-pass filtered
RR
signal.N
, the instaneous frequency of the
RR
signal (in Hz).N
, the instaneous amplitude of the
RR
signal.N
, the evolution of the instaneous
phase shift between the RR
and
Vt
signals.CDM_Analysis
Performs the analysis of a
narrow band component of the RR signal using complex
demodulation (CDM). It estimates the instanenous caracteristics
(amplitude, frequency, phase, dispersion) of the RR signal. The
base frequency can be given by a cosntant value or by an
auxiliary signal which have a slowly varying frequency, like the
respiration signal.
The returned data are shifted to make their time evolution comparable and easily drawn using the PlotSpectralAnalysis function.
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