ECG Feature Extractor VI

LabVIEW 2013 Biomedical Toolkit Help

Edition Date: June 2013

Part Number: 373696B-01

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Owning Palette: ECG VIs

Requires: Biomedical Toolkit

Detects QRS waves and extracts features from electrocardiogram (ECG) signals. This VI can process signals online. This VI needs signals of a complete heart beat cycle to extract features. The ECG features output might delay from the input signal, according to the input block size.

You must manually select the polymorphic instance to use.

Example

Use the pull-down menu to select an instance of this VI.

ECG Feature Extractor (Waveform QRS)

	rough highest heart rate specifies the approximate highest heart rate of the ECG signal, in beats per minute (bpm). rough highest heart rate initializes the internal parameters in order to obtain more accurate results for the first several cycles. The default is 60 bpm.
	initialize? specifies whether to initialize the internal state of the VI. This VI performs calculations that are dependent on all previous data since the VI last ran or since you set initialize? to TRUE. When initialize? is TRUE, this VI restarts the calculation dependency. The default is FALSE.
	ECG specifies the input ECG signal. ECG can be a raw signal or a preprocessed signal. This VI uses ECG only for detecting QRS waves.
	raw ECG specifies the raw ECG signal for feature extraction. raw ECG can be a raw ECG signal or a signal which has been de-noised using a low-pass filter. This VI uses raw ECG to extract features after detecting QRS waves using ECG.
	QRS detector parameters specifies the parameters that this VI uses to detect QRS waves. threshold factor specifies the factor that this VI uses to determine the threshold for separating noise peaks and QRS waves. threshold factor must be greater than 0 and less than 1. The default is 0.1. freq bands specifies the frequency band of the QRS wave of the input ECG signal. low specifies the low value of the frequency band in hertz. The default is 10. high specifies the high value of the frequency band in hertz. The default is 25. QRS onset offset specifies how this VI refines the QRS onset and QRS offset. QRS onset specifies the distance from QRS onset to R peak. QRS offset specifies the distance from R peak to QRS offset. QRS onset specifies the distance from QRS onset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long QRS offset specifies the distance from QRS offset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	ECG features returns the detected features in the ECG signal. Each array element contains the features of a single cycle of the ECG signal. P onset returns the onset time of the P wave. P onset is also the beat start time. P offset returns the offset time of the P wave. QRS onset returns the onset time of the QRS wave. R returns the time of the R wave. QRS offset returns the offset time of the QRS wave. T onset returns the onset time of the T wave. T offset returns the offset time of the T wave. T offset is also the beat end time. amplitude returns the amplitude of the QRS wave. iso level returns the isoelectric level. ST level returns the ST level. P wave? indicates whether the beat contains a P wave. T wave? indicates whether the beat contains a T wave.
	error out contains error information. This output provides standard error out functionality.

ECG Feature Extractor (Array QRS)

	rough highest heart rate specifies the approximate highest heart rate of the ECG signal, in beats per minute (bpm). rough highest heart rate initializes the internal parameters in order to obtain more accurate results for the first several cycles. The default is 60 bpm.
	initialize? specifies whether to initialize the internal state of the VI. This VI performs calculations that are dependent on all previous data since the VI last ran or since you set initialize? to TRUE. When initialize? is TRUE, this VI restarts the calculation dependency. The default is FALSE.
	ECG specifies the input ECG signal. ECG can be a raw signal or a preprocessed signal. This VI uses ECG only for detecting QRS waves.
	raw ECG specifies the raw ECG signal for feature extraction. This input must be raw signal. This VI uses raw ECG to extract other features after detecting QRS waves using ECG.
	QRS detector parameters specifies the parameters that this VI uses to detect QRS waves. threshold factor specifies the factor that this VI uses to determine the threshold for separating noise peaks and QRS waves. threshold factor must be greater than 0 and less than 1. The default is 0.1. freq bands specifies the frequency band of the QRS wave of the input ECG signal. low specifies the low value of the frequency band in hertz. The default is 10. high specifies the high value of the frequency band in hertz. The default is 25. QRS onset offset specifies how this VI refines the QRS onset and QRS offset. QRS onset specifies the distance from QRS onset to R peak. QRS offset specifies the distance from R peak to QRS offset. QRS onset specifies the distance from QRS onset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long QRS offset specifies the distance from QRS offset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	sampling rate specifies the sampling frequency of the ECG signal. sampling rate must be greater than 0. The default is 1.
	ECG features returns the detected features in the ECG signal. Each array element contains the features of a single cycle of the ECG signal. P onset returns the onset time of the P wave. P onset is also the beat start time. P offset returns the offset time of the P wave. QRS onset returns the onset time of the QRS wave. R returns the time of the R wave. QRS offset returns the offset time of the QRS wave. T onset returns the onset time of the T wave. T offset returns the offset time of the T wave. T offset is also the beat end time. amplitude returns the amplitude of the QRS wave. iso level returns the isoelectric level. ST level returns the ST level. P wave? indicates whether the beat contains a P wave. T wave? indicates whether the beat contains a T wave.
	error out contains error information. This output provides standard error out functionality.

ECG Feature Extractor (Waveform All)

	rough highest heart rate specifies the approximate highest heart rate of the ECG signal, in beats per minute (bpm). rough highest heart rate initializes the internal parameters in order to obtain more accurate results for the first several cycles. The default is 60 bpm.
	initialize? specifies whether to initialize the internal state of the VI. This VI performs calculations that are dependent on all previous data since the VI last ran or since you set initialize? to TRUE. When initialize? is TRUE, this VI restarts the calculation dependency. The default is FALSE.
	ECG specifies the input ECG signal. ECG can be a raw signal or a preprocessed signal. This VI uses ECG only for detecting QRS waves.
	raw ECG specifies the raw ECG signal for feature extraction. raw ECG can be a raw ECG signal or a signal which has been de-noised using a low-pass filter. This VI uses raw ECG to extract features after detecting QRS waves using ECG.
	QRS detector parameters specifies the parameters that this VI uses to detect QRS waves. threshold factor specifies the factor that this VI uses to determine the threshold for separating noise peaks and QRS waves. threshold factor must be greater than 0 and less than 1. The default is 0.1. freq bands specifies the frequency band of the QRS wave of the input ECG signal. low specifies the low value of the frequency band in hertz. The default is 10. high specifies the high value of the frequency band in hertz. The default is 25. QRS onset offset specifies how this VI refines the QRS onset and QRS offset. QRS onset specifies the distance from QRS onset to R peak. QRS offset specifies the distance from R peak to QRS offset. QRS onset specifies the distance from QRS onset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long QRS offset specifies the distance from QRS offset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	feature extractor parameters specifies the parameters that this VI uses to extract ECG features. isoelectric limit specifies the limit of amplitude that this VI uses to determine the isoelectric. The unit of isoelectric limit is the same as the unit of the input ECG and raw ECG signals, which is usually in millivolts. If the difference between the maximal and minimal amplitudes within a time period is less than isoelectric limit, the time period is considered as isoelectric. This VI uses isoelectric limit only for the isoelectric between QRS and P waves or between QRS and T waves. isoelectric limit must be greater than 0. The default is 0.05. PR interval specifies the PR interval type of the input ECG signal. This VI uses PR interval to refine P wave detection. The default is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long QT interval specifies the QT interval type of the input ECG signal. This VI uses QT interval to refine T wave detection. The default is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long
	ECG features returns the detected features in the ECG signal. Each array element contains the features of a single cycle of the ECG signal. P onset returns the onset time of the P wave. P onset is also the beat start time. P offset returns the offset time of the P wave. QRS onset returns the onset time of the QRS wave. R returns the time of the R wave. QRS offset returns the offset time of the QRS wave. T onset returns the onset time of the T wave. T offset returns the offset time of the T wave. T offset is also the beat end time. amplitude returns the amplitude of the QRS wave. iso level returns the isoelectric level. ST level returns the ST level. P wave? indicates whether the beat contains a P wave. T wave? indicates whether the beat contains a T wave.
	error out contains error information. This output provides standard error out functionality.

ECG Feature Extractor (Array All)

	rough highest heart rate specifies the approximate highest heart rate of the ECG signal, in beats per minute (bpm). rough highest heart rate initializes the internal parameters in order to obtain more accurate results for the first several cycles. The default is 60 bpm.
	initialize? specifies whether to initialize the internal state of the VI. This VI performs calculations that are dependent on all previous data since the VI last ran or since you set initialize? to TRUE. When initialize? is TRUE, this VI restarts the calculation dependency. The default is FALSE.
	ECG specifies the input ECG signal. ECG can be a raw signal or a preprocessed signal. This VI uses ECG only for detecting QRS waves.
	raw ECG specifies the raw ECG signal for feature extraction. This input must be raw signal. This VI uses raw ECG to extract other features after detecting QRS waves using ECG.
	QRS detector parameters specifies the parameters that this VI uses to detect QRS waves. threshold factor specifies the factor that this VI uses to determine the threshold for separating noise peaks and QRS waves. threshold factor must be greater than 0 and less than 1. The default is 0.1. freq bands specifies the frequency band of the QRS wave of the input ECG signal. low specifies the low value of the frequency band in hertz. The default is 10. high specifies the high value of the frequency band in hertz. The default is 25. QRS onset offset specifies how this VI refines the QRS onset and QRS offset. QRS onset specifies the distance from QRS onset to R peak. QRS offset specifies the distance from R peak to QRS offset. QRS onset specifies the distance from QRS onset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long QRS offset specifies the distance from QRS offset to R peak. The default value is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	sampling rate specifies the sampling frequency of the ECG signal. sampling rate must be greater than 0. The default is 1.
	feature extractor parameters specifies the parameters that this VI uses to extract ECG features. isoelectric limit specifies the limit of amplitude that this VI uses to determine the isoelectric. The unit of isoelectric limit is the same as the unit of the input ECG and raw ECG signals, which is usually in millivolts. If the difference between the maximal and minimal amplitudes within a time period is less than isoelectric limit, the time period is considered as isoelectric. This VI uses isoelectric limit only for the isoelectric between QRS and P waves or between QRS and T waves. isoelectric limit must be greater than 0. The default is 0.05. PR interval specifies the PR interval type of the input ECG signal. This VI uses PR interval to refine P wave detection. The default is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long QT interval specifies the QT interval type of the input ECG signal. This VI uses QT interval to refine T wave detection. The default is Middle. 0 Very short 1 Short 2 Middle (default) 3 Long 4 Very long
	ECG features returns the detected features in the ECG signal. Each array element contains the features of a single cycle of the ECG signal. P onset returns the onset time of the P wave. P onset is also the beat start time. P offset returns the offset time of the P wave. QRS onset returns the onset time of the QRS wave. R returns the time of the R wave. QRS offset returns the offset time of the QRS wave. T onset returns the onset time of the T wave. T offset returns the offset time of the T wave. T offset is also the beat end time. amplitude returns the amplitude of the QRS wave. iso level returns the isoelectric level. ST level returns the ST level. P wave? indicates whether the beat contains a P wave. T wave? indicates whether the beat contains a T wave.
	error out contains error information. This output provides standard error out functionality.

Example

Refer to the ECG Feature Extractor VI in the labview\examples\Biomedical\Biosignal directory for an example of using the ECG Feature Extractor VI.