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ADS1292R: 50Hz noise in some situations

Rafael Raya
Prodigy 10 points
Part Number: ADS1292R

Hi forum!

I have designed a sensor to measure muscle activity (EMG) using ADS1292R. The signal is correct in most cases, but sometimes, the noise of 50Hz appears with high amplitude. I would like to ask for a review of my hardware design and software configuration just in case there is something that I can improve to reduce this noise.

 I am using RLD with Ground electrode connected to RLDout and RLDsens is 0b00101111

I attach schematics and register configuration.

I real appreciate your support,

bestPCB_EMG_MDR_v23.pdfads1292r.cpp

  • 0
    TI__Mastermind 19815 points

    Hi,

    ADS1292R is not designed for EMG application.

    Do you have/use ADS1292R evaluation board/kit(EVM)?

    What is the data rate(DR) do you select?

    Can you do a external short and internal short to see if 50/60 Hz noise are there?

    Can you probe the nodes from the electrodes along the path to input channels to see where do you see the 50 Hz noise?

    I see AVDD is setup by MIC5205? Can you check whether VCC, AVDD is clean/free of 50/60Hz noise?

    What voltage do you select for the RLDREF? GND or AVSS or (AVDD+AVSS)/2? Can you check whether RLDREF is clean/free of 50/60Hz noise?

    Can you try use GND or AVSS or (AVDD+AVSS)/2 as reference electrode and observe the results?

    I see you have 470pF, 680k Ohm Low Pass Filter(LPF) with cutoff frequency around 0.5Hz.

    If this is for EMG(i.e. usually higher frequency band) application, Do you want to try use the LPF with cutoff frequency at 50 or 60Hz?

    In the meantime, please take a look of this thread - 

    e2e.ti.com/.../ads1198ecgfe-pdk-elimination-of-50hz-noise

    EVM user guide may suggest use Multiband-pass Filter -
    Multiband-pass filter (MBF) is used for removing unwanted signals and power line noise from the live data.
    The MBF digital filter is a 161 order FIR filter with Hamming window having cut-off at 150Hz and notch at
    50/60 Hz. The notch frequency is selectable from the PC application. This filter provides a very sharp cutoff
    around 150 Hz with attenuation more than 30 dB at the stop band. The notch at 50/60 Hz provides
    attenuation of more than 30 dB. Sampling frequency is 500 samples/ second.

    Thanks.

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Hi,

    This ticket/thread has been pending for more than 1 week.

    For house cleaning, I am closing this ticket/thread.
    If you may have other question, feel free to open another ticket/thread.

    Thanks