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ADS1299 EVM power supply - 60 Hz, 120Hz, 180 Hz noises

José Jair Alves Mendes Júnior
Intellectual 460 points
Other Parts Discussed in Thread: ADS1299

Hello!

I used ADS1299 EVM to capture an EMG signal of my own arm (biceps). I am using differential mode, with a third electrode connected to REF (pin 6 of JP25). SRB1 is enabled (let me know if there is something wrong with this setup).

I am using +- 2.5V supply mode and most jumpers are as default.

Looking at my raw signal, (and the FFT) I noticed that most noises are coming from 60,120,180, 240 Hz.

Data sample rate is 1000 SPS.

The picture below already has a 60Hz notch filter, otherwise it would be much worse (I used the filter built-in the software that came with the board). Also, let me know if you wanna look at the raw signal without 60Hz filter.

In the recording below I made 3 contractions:

I exported these data to matlab so I could apply two other notch filters at 120 Hz and 180 Hz. This is the result:

I just want to make sure that I am getting the lowest noise possible before applying the filters.

So my question is: is it possible to supply the board with some sort of battery instead of using the power brick that came with the board?

I am doing theses experiments in a lab in my university.

Thanks in advance

  • 0
    TI__Mastermind 38745 points
    Hey JJ,

    First, I will not be able to guide you on matters related to human testing since this EVM is to be used for device evaluation with a patient simulator or other signal source.

    For the more generic question about power supplies, I doubt the noise is coupling in through the device power supplies. The PSRR on this device is very small. In addition, properly decoupled power supplies will filter out noise on the rails as well. My hypothesis is that all the noise related to the wall power frequency is coupling in through the inputs by way of fluorescent lights or lab machines. Using digital filters to eliminate harmonics related to the mains frequency is standard operating procedure for many similar applications.

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    Intellectual 460 points
    I see, so it seems that's the right procedure.

    Thanks =]