Method and device for analyzing a periodic or semi-periodic signal

A device for reducing noise in signals having successive substantially repetitive portions, comprising:

• an aligner for aligning at least some of said substantially repetitive portions one with another,
• a repetitive portion selector for selecting repetitive portions for passing to said iterative averager on the basis of a comparison with a reference portion, and
• an iterative averager operative to superimpose and average said aligned, selected portions to produce a running average thereof.

A waveform frequency component alignment device for aligning first frequency components of waveforms having first frequency and second frequency components, the device comprising:

• Band pass filters for extracting respective first and second frequency components of said waveform,
• a first frequency component aligner for determining a first frequency alignment point of a current waveform with another waveform based on respective first frequency components,
• and a second frequency aligner for aligning said second frequency components of said respective waveforms based on said first frequency alignment point.

A device for analyzing high frequency components of ECG signals, comprising

• a data extractor for extracting said high frequency components and
• a data analyzer for determining, from a change over time in at least a part of said high frequency component, whether said ECG signal contains an indication of the presence of ischemia.

A method for reducing noise in signals having successive substantially repetitive portions, comprising:

• aligning at least some of said substantially repetitive portions one with another,
• selecting repetitive portions for passing to said iterative averager on the basis of a comparison with a reference portion, and
• superimposing and averaging said aligned, selected portions to produce a running average thereof.

A method of aligning waveforms having first and second frequency components, said second frequency components being more subject to noise than said first frequency components, the method comprising:

• extracting respective first and second frequency components of said waveform,
• determining an alignment point of a current waveform with another waveform based on respective first frequency components, and
• aligning said second frequency components of said respective waveforms based on said alignment point.

A method for analyzing high frequency components of ECG signals, comprising the steps of:

• extracting said high frequency components and
• determining, from a change over time in at least a part of said high frequency component, whether said ECG signal contains an indication of the presence of ischemia.

A method of producing a noise reduced waveform from a series of substantially similar repeated waveforms having superimposed noise, the method comprising:

• selecting waveforms having a highest cross-correlation with a preselected reference waveform, and
• carrying out iterative averaging steps using said selected waveforms.