How to measure distance between R-R peaks

[infra444]

Kindly check the vi with these recorded signals wheather the vi is working properly, these are the recorded signals from my DAQ device.

thank you,

abi

[rpursley8]

I looked at your files and I do not see much in the way of ECG.  The signals are dominated by what I will assume to be a respiration signal.  The ECG is there, but of such small amplitude that your filtering cannot be selective enough to separate it from the respiration signal.

If this is the best signal for ECG that you can acquire, then you will have to figure out a new approach.

[infra444]

thanks you for your reply, ya this is the best signal I could get from Daq acqusition, in fact I have sent you only the better ones, so what method can I use with such a signal, as I am dealing with these signals only and the other conventional ECG I sent before was just used to compare both the ECG's.

ya your right here respiration signals are overlapping with ECG, so is there any way to deal in such a situation.

[Steve.J]

How are you measuring the ECG?  Is this signal acquired using regular contact electrodes/gel and a ECG amplifier connected to a DAQ board?

[infra444]

no this is contactless capacitively coupled ECG, plate electrodes are attached to car seat at the lower back and then the signal is extracted with a ECG amplifier, and a driven circuit which is then fed on to a DAQ acqusition device. This is completely contactless, not attached on to the body using any gel or so.

[Steve.J]

OK - that explains the waveform...

[rpursley8]

You should look into LMS adaptive filtering.  This should be able to filter out the respiration signal.

[rpursley8]

Take a look at the attached.  I have added a simple adaptive filter that effectively filters out the respiration.  The ECG signal is still pretty poor, but easier to see.

[infra444]

thank you for mod vi, I am not very well conversed with adaptive filter toolkit, can you expalin a bit about it and also is it not possible to measure the heart rate and R-R intervals with this adaptive filter concept.

[ZJ.Gu]

Hi,

I have a try of you signal of "R10-R10_closed cover_Bhavin1_1.lvm". ECG signal is very weak. However, choosing a suitable filter will help improve the SNR. Then using peak detection technique to find the heartbeats.

During the peak detection ,the threshold should be adaptive as the ECG signals are so weak and changing. Here I only set to a fixed threshold 0.02. For adaptive threshold in ECG QRS detection, you could refer to the paper (although it is very old :))

J. Pan and W.J. Tompkins, “A real-time QRS detection algorithm,” IEEE Trans. Biomed. Eng., vol. 32, pp. 230-236, 1985.