US 7,353,127 B2 · Apparatus and method for detection and quantification of oscillatory signals

Abstract

A method of determining the location in time of maxima and/or minima of an oscillatory signal. The method may have application to measurement of biological signals, in particular measurement of heart rate from a pulsatile blood signal. The method includes a first stage including the steps of observation over a measurement period, identifying large local maxima or minima and computing an average interval between the identified local maxima or minima. One or more exclusion periods are located in time in the oscillatory signal, having a duration dependent on the average interval, the exclusion periods used to reject false maxima or minima. Maxima or minima may also be detected as an absolute maximum or minimum between crossing points of a fast and a slow moving average of the oscillatory signal. An exclusion period may also be used to reject false maxima or minima when crossing points are used. Apparatus for performing the method is also claimed.

Claims26

Dependent claims

A method of determining the frequency or period of a heartbeat, the method including the steps of:

a) using a sensor to generate an electrical oscillatory signal representative of variation of the heartbeat, and using a computing apparatus to:
b) observe the oscillatory signal by detecting the amplitude of the oscillatory signal;
c) compute a first and a second moving average of the oscillatory signal, the first moving average having a first averaging time interval and the second moving average having a second averaging time interval longer than the first averaging time interval;
d) determine the location in time of a plurality of crossing points, wherein a crossing point is a point of intersection between the first and second moving averages;
e) define at least one measurement period as the interval between two crossing points;
and
f) determine the location in time of an absolute maximum or minimum of the oscillatory signal within the or each measurement period;
and
g) use the location in time of an absolute maximum from step f) to determine the frequency or period of the heartbeat.

6 more elements

Dependencies are inferred from the claim text.

Apparatus and method for detection and quantification of oscillatory signals

Life of this patent

Apparatus and method for detection and quantification of oscillatory signals

Life of this patent

Abstract

Claims26