Analysis of ECG signal

[Luanna]

Hello, Randall.
I´ve been using your EKG Processor vi and when i input some of my data i noticed that the EKG peaks appear to have their Time Location shifted, mainly at the end. I used that formula Time[i] = t0 + dt * Location[i] and i plot my waveform using time location instead of just location. Have you experienced that? I´ve attached a part of the waveform.
Please, if you could help me, i´d very much appreciate it.
Regards,

Luanna

[Luanna]

Sorry, forgot to send the image.

Regards,

Luanna

[rpursley8]

Take a look at where the peak is in the Enhanced EKG signal.  Is it also shifted with respect to the input signal?

If it is then the shift is just a result of the processing and as long as it is about the same, your heart rate measurements are fine.

[Luanna]

Randall, i´ll test what you asked (the enhanced signal) but i noticed that on the original ECG signal the peak locations are shifted since the beginning, but it gets worse as the signal advances in time, that is, the shift is not always the same size.

Actually, my main corcern is not this shifted time locations, but the power spectrum. I ran your example and i dont know if im wrong, but shouldnt the spectrum have just one major peak?

Thanks again for your help!
Regards,

Luanna

[rpursley8]

Can you post an example of your data?  I don't see how the spacing between peaks can increase, the enhanced signal is generated from the  original.

[Luanna]

Hello, Randall. Here it goes a piece of data. Thank you!

Regards,

Luanna

[rpursley8]

I think you forgot to attach the data.

[Luanna]

Sorry again...i´ve attached it on the other thread and i forgot this one. Here it goes!

Thank you!

Luanna

[rpursley8]

Attached is a copy of the EKG Processor vi with your data in it.  I may have modified it some to get the heart rate.  The results look good to me.  I had to modify the level for the peak detection to eliminate a false peak from the glitch in the middle of your data.  I don't not see any shift between the original data and the enhanced data.

[Luanna]

Hi, Randall. Thank you for the vi. Considering i´m using almost exactly your algorithm with the difference that instead of Locations i calculate Time Locations, do you think that this formula TimeLocations[i] = t0 + dt*Locations[i] may be the cause of the shift?

Regards,

Luanna