Method for arbitrary two-dimensional scaling of phonocardiographic signals
First Claim
1. A method for arbitrary time and/or frequency scaling of phonocardiographic signals obtained from a transducer and subjected to digital spectral analysis, characterised in that the signals are converted on a running basis to a sinusoidal model representation, that a time and/or frequency axis scaling is defined and used to control the amplitudes and phases of the sinusoids, which are subsequently added to create a time and/or frequency scaled representation of the phonocardiographic signal.
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Abstract
A heart signal comprising both first and second heart sounds and murmurs occurring due to various heart conditions is modelled by a sum of sinusoids automatically selected to represent the heart sound without a noise component. In an analysis step the signal parameters are measured, in an interpolation and transformation part Ω(t) and A(t) are interpolated from one window position to the next window position, and a synthesis part reconstructs the transformed heart signal. The transformations are transformations in either time scale (with unchanged frequency content) or frequency scale (with unchanged time progression), or both. Furthermore a dynamic transformation of an arbitrary heart signal to a fixed number of beats per minute is made possible.
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8 Claims
- 1. A method for arbitrary time and/or frequency scaling of phonocardiographic signals obtained from a transducer and subjected to digital spectral analysis, characterised in that the signals are converted on a running basis to a sinusoidal model representation, that a time and/or frequency axis scaling is defined and used to control the amplitudes and phases of the sinusoids, which are subsequently added to create a time and/or frequency scaled representation of the phonocardiographic signal.
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