ECG Waveform

TriggsTriggs Orlando, FL
edited April 2019 in Opportunities
Hey all! I'm pretty new to this and I was wondering if you had any tips on what I should get/how I should go about getting the waveform from an ECG and translating it into pulsecode modulation? I was looking at the OpenBCI pulse sensor, but I was also told by some colleagues that a Holter Monitor was necessary. If anyone could help with either the data obtaining or data manipulating side of my problem, I'd be thankful.

Comments

  • BillhBillh
    By pulsecode do you mean a PCM audio file like WAV or some type of EKG/ECG format?  Many modern Holter devices use the EDF or similar file format for recording.
  • TriggsTriggs Orlando, FL
    Yeah I'm talking about the audio file type. From what I understand EKG/ECG graphs are represented as voltage samples at a specific rate, and if one were to translate that into amplitude and increase the sample rate, it would be very similar to PCM waveform. My question would be how to make that leap (if possible).
  • wjcroftwjcroft Mount Shasta, CA
    Triggs, Bill, hi.

    There are some converter programs that go between EDF / BDF and WAV.


    OpenBCI GUI can output in BDF (which is the 24 bit version of 16 bit EDF). And BDF can be truncated to EDF as well.


    You can also convert the CSV output file from the GUI to WAV with some of these,


    Regards,

    William

  • wjcroftwjcroft Mount Shasta, CA
    The Pulse Sensor is a PPG, thus misses much of the detail of a true ECG. PPG can give you heart rate and fairly accurate HRV, but no more. 

    Can you elaborate why you are drawn to WAV? As Bill states, usually these recordings are in other formats. Is your app working from recordings, or does it analyze the ECG in live realtime?
  • BillhBillh
    edited April 2019
    Probably getting one or more bipolar lead EKG recordings from the chest using OpenBCI, saving to BDF, and then using EDFBrowser to make the BDF file into a WAV file would work for you. 

    I assume that you have your analysis pipeline working depending on having a WAV file on disk? If not, you might be able to just analyze from the BDF file. That is if you record first, then analyze a recorded file.

    If you need realtime analysis on ongoing recording of WAV data, that would be more involved.

  • TriggsTriggs Orlando, FL
    Hey Bill and wjcroft! Thanks for the replies. My interest in WAV/PCM is to discern and the sample the timbre of a heartbeat by taking the bpm and increasing it to a pitched note (ex. 440 Hz). It's my understanding that ECG/EKGs are sampled at a rate of 200 Hz or more, so if one were to take those samples and compress them into a shorter time period, then It would create a fundamental sound. That's the theory at least. If the waveform of a normal heartbeat at 60 bpm would be played it would sounds like a 1 Hz frequency wave but if sped up it would become a unique sound... yknow?
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