ipfm¶

Estimate instantaneous heart rate using the integral pulse frequency modulation model.

Syntax¶

function [outputSignal, m] = ipfm(tn, varargin)

Description¶

SP = IPFM(TN) estimates the spline representation of instantaneous heart rate from the normal beat occurrence time series TN using the integral pulse frequency modulation model. TN is a vector of normal beat occurrence times in seconds. SP is a spline representation that can be evaluated with SPVAL.

IHR = IPFM(TN, FS) evaluates the IPFM spline at the uniformly sampled time vector TM = TN(1):1/FS:TN(end), where FS is the desired sampling frequency in hertz. FS must be positive. IHR is the instantaneous heart rate in hertz.

SP = IPFM(TN, 'SplineOrder', SPLINEORDER) uses the specified spline order for the spline interpolation stage. The default spline order is 14.

IHR = IPFM(TN, FS, 'SplineOrder', SPLINEORDER) evaluates the IPFM spline using the specified spline order.

[IHR, M] = IPFM(TN, FS, ...) also returns M, the modulating signal obtained by removing the low-frequency trend of IHR and normalizing the residual by that trend. This output requires FS greater than 0.06 Hz and at least 13 samples on the output grid.

Source¶

View source code

Example¶

% Estimate instantaneous heart rate from beat occurrence times
tkData = readtable('../../fixtures/ecg/medicom_mtd_r_wave_timing.csv');
tn = tkData.r_wave_times(1:100);
fs = 4;

% Evaluate the IPFM spline and compute the modulating signal
[ihr, m] = ipfm(tn, fs);
tm = (tn(1):1/fs:tn(end))';

% Plot results
figure;
subplot(2,1,1);
plot(tm, ihr);
ylabel('Heart rate (Hz)');
title('IPFM-Based Instantaneous Heart Rate');

subplot(2,1,2);
plot(tm, m);
xlabel('Time (s)');
ylabel('Modulating signal');
title('IPFM Modulating Signal');

View executable example

See also¶

• SPAPI
• SPVAL
• FNDER