• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 355 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1299EEGFE-PDK: How to process data in ECG implementation

mmWaves
Intellectual 260 points
Part Number: ADS1299EEGFE-PDK
Other Parts Discussed in Thread: ADS1299

I have an ADS1299EEG FE Rev A board and I am trying to use it as an ECG front end.

I have three electrodes attached to a person with this placement.

They are connected to the ADS1299 through the J6 jumpers like so:

  • LA  -> CH1+
  • RA -> CH2+
  • LL -> CH3+

I collected data for 30 seconds, but the frequency was really high. While the average resting heart rate is 60 bpm or 1 Hz the signal I collected reported had a frequency of 60 Hz.

When I looked at the scope tab I saw that the signal did in fact have a very high frequency and the peaks were ~30 samples apart.

I'm not familiar with this hardware so I'm unsure if this is a mistake or if I should be performing some kind of post processing on the data.

Any suggestions on why I am getting such and odd recording?

  • 0
    TI__Guru 63196 points

    Hello,

    Thanks for your post.

    Each channel on the ADS1299 is truly differential and expects an input signal applied to both the (+) and (-) input pins. From the description above, it sounds like you only connected signals to the positive inputs, so the negative inputs are likely floating. This allows 60-Hz power line noise to couple into the device and convert to a differential noise signal. This is what you are seeing in the FFT - it's just a coincidence that 60 BPM is your ECG input signal. ECG frequency content actually ranges from near DC (0.05 Hz) up to ~150 Hz, independent of the cardiac cycle period.

    ECG leads are differential, so I would connect the electrode inputs as defined by standard ECG lead equations (i.e. Lead I = LA - RA, so IN1P = LA and IN1N = RA). This will help to reduce the noise coupling.

    Best regards,

  • 0 in reply to Ryan Andrews
    Intellectual 260 points

    Thank you, that makes a lot of sense. This signal is much better than what I had before, but do you have any other recommendations on how I can reduce noise? Do I even need to plug the LL electrode into the board?

  • 0 in reply to mmWaves
    TI__Guru 63196 points

    That depends on what you're trying to measure. At a minimum, each channel is expecting a differential input, and the common-mode voltage of those inputs should sit near mid-supply of the PGAs to maintain linear operation.

    We have some training material that may help you learn more about bio-potential applications on our ADS129x BIOFAQ E2E page.

    Best regards,