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ADS1299: Collect EEG signals to find periodic noise interference issue

Liang Li
Prodigy 10 points
Part Number: ADS1299

I use the ADS1299 acquisition of EEG of body wih 3 electrodes , +,- and ref.  and connected methods like as fiure.:

 

The test result has some issues like as follow  and there are many glitches on the EEG signal, as shown in the figure below., as shown in the figure below.

Could you please help following:

1. There is such a weak interference signal of about 2uV, is there a way to suppress it for ADS1299?  I am  not sure where this inreference signals come from ? Could you provide the debugging methods?

2.  The interfering signal seems to be a power frequency 50Hz signal,and Does the ADS1299 have a way to suppress power frequency signals?

3. Is the application connection above correct?

4.In the application of ADS1299 EEG system, is there any design reference for suppressing 50Hz power frequency signal?

  • 0
    TI__Mastermind 19815 points

    Hi,

    Which board are you using?

    Do you have/use an ADS1299 evaluation kit/board(EVM)?

    Have you tried the same experiments&tests using ADS1299 evaluation kit/board (EVM)?

    If not, it's suggested to try the similar experiments&tests using ADS1299 evaluation kit/board to see whether the interference are there or not and establish some baseline&reference.

    Also, are the signals sources from human subject?  Have you tried with an EEG or ECG simulator first and see how the signal looks like e.g. noise level? And, how does the baseline&noise floor look like if without connecting to any sources and/or short(by internal(i.e. set CHnSET register's 2:0 MUXn[2:0]  to 001 or external) the inputs?

    Consider using shorter length of cable/wire.

    Electrode materias&skin conditions&environment also maters.

    Do a FFT on the waveforms you recorded and figure out what might be the frequency of the interference.

    ----------------------

    ADS1299 has high CMRR to suppress common mode noises - datasheet page 9

    CMRR Common-mode rejection ratio fCM = 50 Hz and 60 Hz(2) –110 –120 dB

    SNR Signal-to-noise ratio VIN = –2 dBFs, fIN = 10-Hz input, gain = 12 121 dB

    -------------------------------------------------------------------

    By the way, the picture resolution is very low, so it's hard to read. Please upload better resolution pictures/screenshots in the future.

    Thanks