ECG Feature Extraction

[Strokes]

Hi,

I've recently downloaded the Biomedical startup kit 3.0 as it seemed on paper like just the NI toolkit I was looking for. I want to extract various parameters from an ECG signal, the main one being the R-R intervals. I imported my ECG data in .tmds format into the ECG Feature Extractor and played around with the settings but can't seem to acquire accurate results.

I've attached a tdms file below that contains my ECG data sampled at 256Hz. The first channel is timestamp, the second channel is the ECG lead RA-LL and the third channel is ECG lead LA-LL.

Maybe it's just a matter of configuring the ECG Feature Extractor in the right way but I don't seem to be able to get anything meaningful out of it.

If more information needs to be provided, just shout.

[ZJ.Gu]

Hello,

Where are you getting the tdms? It is because each channel in your tdms file has no sampling rate info. I modify your tdms and attach here. I assume the dt is 3.90625ms from your tdms file. You could have a try again.

[Strokes]

Thanks for the assistance.

I'm getting the tdms file using the Shimmer wireless sensor platform and an ECG signal generator.

Yes, your correct, the dt is 3.90625ms! I see you've edited the root group in the tdms file to provide the sampling rate info.  I assume you did this manually? If so is there anyway to achieve this programatically?

Thanks again

[ZJ.Gu]

Hi,

I did it using LabVIEW TDMS VIs. You could find it under FileIO -> TDMS Streaming. You could use set properties VI to set a "wf_increment" (dt) property to group or channel.

What is Shimmer wireless sensor platform?

ZJ Gu

[Strokes]

Thanks I will look into the tdms blocks you've mentioned (i've only used open/read/write/close etc. before)

The Shimmer wireless sensor platform is small lightweight (22g) sensor incorporating wireless ecg, emg, gsr, accelerometer, gyroscope, magnetometer, gps, tilt and vibration sensors.

LabVIEW support was recently released to benefit Shimmer users in the development of applications using LabVIEW

https://decibel.ni.com/content/groups/wire/blog/2011/07/11/new-shimmer-labview-library

I've one more question and if you could answer it, it would be great. Is it possible to access biomedical blocks like those used in biomedical workbench in LabVIEW's function palatte? I sent an email requesting the source code and if this does the trick, then great. The reason being is i'd like to incorporate the ECG feature extractor in LabVIEW.

[T2dei]

Hey Strokes,

I am acquiring ECG signals from Shimmer as well and I am facing the same problem. The features extracted are not meaningful. Could you advise me what to do based on your experience?