ECG Signal Filtering

[Bildavid]

How you guys doing ?

Well to put it bluntly , i just need some help right here , i hope you can cooperate guys .

I am working on a thesis for my final year project . and i am using labview in it, but i am facing some dificulties .

I have implemented an ECG circuit that detedts the tiny electrical impulses of the human heart . I am trying to acquire the ECG signal via serial port in order to display it using labview .

I did it . but i am experiencing some dificulties while designing the filters . I have implemented buterworth filters with 10-25 HZ as low and high cutoff frequencies. i have also used so many ways but none of them had helped .

Could you please suggest anything useful ?

Any help would be greatly appreciated .

Thank you

Bill David

[Matt_McLaughlin]

Hi Bill,

I just want to quickly point you to a couple of resources where you are more likely to get assistance with your questions. There are several similar discussion and a lot of knowledgeable users within the Biomedical User Group. The NI Discussion Forums are another option. There is a very active community on the forums and you will likely see a very quick response to your questions.

Thanks,

Matt

[Bildavid]

Thanl you Matt for the reply yes i will follow the links hoping that i get some help .

Again thank you .

[rpursley8]

Can you post your code?  I can take a look at it if you like.  You can also send it to my email in my profile if you would prefer.

[Bildavid]

Dear friend

i would love to attach my VI to have a look at it but the web browser that i am using is not allowing me to attach any file . can you please provide me some filtering techniques samples taht i can find useful in my application ?

I wanted to use the discrete wavelet transform to denoise the signal . but just need some instructions to follow in order to denoise my signal .

Thanks alot .

Bill David

[rpursley8]

Well, a 10 Hz low cutoff seems really high for ECG.  If this is in humans, ECG usually ranges between 1 and 2 Hz repetition rate with a minmum bandwidth of about 20 Hz to get a good representation of the signal.  A low cutoff around 0.1 Hz might be more appropriate to remove baseline drift.  Sampling rate of about 50 Hz would good enough for ECG, but I don't know what kind of noise sources you are trying to filter out.  Do you have a hardware filter built into your ECG detection circuit.  If so, what is the cutoff of that circuit?

[Bildavid]

Dear friend thank you for the very fast reply

YES i do have a filter in my built circuit . I actually used a second order low passive filter with cutoff frequency of 15.9 HZ . now when trying to acquire the signal via  serial port the QRS COMPLEX could be distinguished from the signal . I mean they 25 % appear in the signal . but it seems that noises are disturbing the signal .

Talking about the kind of noise I am dealing with I am sure that even ECG's that you can find in clinics and hospitals give you a signal with baseline wandering . this is the first noise i am facing . and we do not have a doubt the power line interference .

I JUST need  a specialized filter design to obtain readable ECG signal with clean QRS complex.

any suggestions

REGARDS

[rpursley8]

Do you have the Wavelet Analysis toolkit, or are you planning on using the Wavelet Transform in the Signal Processing Toolkit?

[Bildavid]

yes sir i have it . registered version

[rpursley8]

Send me an email and I will send you a vi that you can look at for denoising.  What version of LabVIEW do you run?

mailto:pursley@helix.nih.gov