ECG sensing with noise filtering
Various embodiments are directed to signal processing. In accordance with example embodiments, methods and apparatuses involve using at least two electrodes that sense an ECG signal. A denoising module is communicatively coupled to the at least two electrodes, and receives the ECG signal sensed by the sensing electrodes. The denoising module includes circuitry that conditions and digitizes the ECG signal, and a computing circuit that processes the digitized ECG signal to denoise the ECG signal. A communications circuit generates a communication including the denoised ECG signal for access by a remote device.
1. An apparatus comprising:
digitizing circuitry configured and arranged to generate a digitized ECG signal from an analog ECG signal; and
a computing circuit coupled to receive the digitized ECG signal from the digitizing circuitry and configured and arranged to generate a denoised ECG signal from the digitized ECG signal, the denoised ECG signal having, relative to the digitized ECG signal,
an improved signal-to-noise ratio of at least 15 dB as measured using the ANSI EC 57 standard, and
a quality of signal reconstruction greater than 95%.
2. The apparatus of claim 1 , wherein the computing circuit is configured and arranged to generate the denoised ECG signal from a digitized ECG signal that has a signal-to-noise ratio of 0 dB and that includes a substantially noise-free ECG with white noise added as prescribed in the ANSI EC 57 standard.
3. The apparatus of claim 2 , wherein the substantially noise-free ECG is an ECG having a signal-to-noise ratio of greater than 30 dB according to the ANSI EC 57 standard.
4. The apparatus of claim 1 , wherein the computing circuit is configured and arranged to generate the denoised ECG signal by:
decomposing the digitized ECG signal from a first domain into subcomponents in a second domain that is different than the first domain, and
selecting and combining ones of the subcomponents based upon a time-based distribution of the subcomponents.
5. The apparatus of claim 4 , wherein the computing circuit is configured and arranged to select and combine the ones of the subcomponents by:
identifying target subcomponents of the digitized ECG signal that are associated with a desired ECG signal based upon the time-based distribution of the subcomponents, and
reconstructing a denoised ECG signal in the first domain from at least two of the identified target subcomponents.
6. The apparatus of claim 1 , wherein the computing circuit is a portable or desktop computer.
7. The apparatus of claim 1 , wherein the computing circuit is a mobile telephone configured and arranged to receive the digitized ECG signal.
8. The apparatus of claim 1 , wherein the quality of signal reconstruction (QSR) is defined as
QSR
=
100
%
*
(
1
-
∑
i
(
x
cl
i
-
x
den
i
)
2
∑
i
(
x
cl
i
)
2
)
,
where x cl is the digitized ECG signal and x den is the denoised ECG signal.
9. The apparatus of claim 1 , wherein the computing circuit is configured and arranged to generate the denoised ECG signal from an analog ECG signal that is obtained via at least two electrodes and subsequently digitized.
10. An apparatus comprising:
at least two electrodes configured and arranged to sense an ECG signal; and
a computing circuit configured and arranged to generate a denoised ECG signal from the sensed ECG signal having, relative to the sensed ECG signal,
an improved signal-to-noise ratio of at least 15 dB as measured using the ANSI EC 57 standard, and
a quality of signal reconstruction greater than 95%.
11. An apparatus comprising:
an electrode circuit attached to an outer surface of a hand-held device, the electrode circuit configured and arranged to sense heart-related signals upon contact with a surface of a body of a living being and to convert the sensed heart-related signals to ECG electrical signals; and
a converter circuit integrated with and electrically connected to the electrode circuit, said converter circuit configured and arranged to receive the ECG electrical signals generated by the electrode circuit and to generate a digitized ECG signal based upon the ECG electrical signals; and
a computing circuit communicatively coupled to the converter circuit and configured and arranged to generate a denoised ECG signal from the digitized ECG signal, the denoised ECG signal having, relative to the digitized ECG signal,
an improved signal-to-noise ratio of at least 15 dB as measured using the ANSI EC 57 standard, and
a quality of signal reconstruction greater than 95%.
12. The apparatus of claim 11 , wherein the hand-held device is a smart phone.
13. The apparatus of claim 11 , wherein the computing circuit is included in the converter circuit and is configured and arranged to communicate a denoised ECG to said hand-held device.
14. The apparatus of claim 11 , wherein the computing circuit is incorporated into the hand-held device.
15. The apparatus of claim 11 , wherein the hand-held device is configured and arranged to diagnose or screen cardiac-related disease.
16. The apparatus of claim 10 , wherein the at least two electrodes are configured and arranged to contact and adhere to a surface of a patient's chest, and include an adhesive-backed patch as part of the electrodes.
17. The apparatus of claim 10 , wherein the at least two electrodes are configured and arranged to contact extremities of a patient's arms, and to sense the ECG signal therefrom.
18. An apparatus comprising:
an electrode circuit attached to an outer surface of a wearable device, the electrode circuit configured and arranged to sense heart-related signals upon contact with a surface of a body of a living being and to convert the sensed heart-related signals to ECG electrical signals; and
a converter circuit integrated with and electrically connected to the electrode circuit, said converter circuit configured and arranged to receive the ECG electrical signals generated by the electrode circuit and to generate a digitized ECG signal based upon the ECG electrical signals; and
a computing circuit communicatively coupled to the converter circuit and configured and arranged to generate a denoised ECG signal from the digitized ECG signal, the denoised ECG signal having, relative to the digitized ECG signal,
an improved signal-to-noise ratio of at least 15 dB as measured using the ANSI EC 57 standard, and
a quality of signal reconstruction greater than 95%.
19. The apparatus of claim 18 , wherein the electrode circuit is configured and arranged to attach to a patient's chest or arm extremities.