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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. 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.

Source Code

View source code

Examples

% Estimate instantaneous heart rate from beat occurrence times
tkData = readtable('../../fixtures/ecg/ecg_tk.csv');
tn = tkData.tk(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 detailed example

See Also

Module: HRV | Last Updated: 2026-03-18