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AFE4490: There is a 50Hz noise in my signal even when every thing is disconnected from power line

Part Number: AFE4490

Hi,

My Laptop is disconnected from the power line operating on battery. The AFE4490EVM is powered through the USB port from my laptop. So everything is decoupled from power line. And yet, I see a peak on the 50Hz frequency in the FFT of my signal.

Have somebody an explanation for that? Is that due to EMI?

  • Hello Farzad,

    Can you disconnect the spo2 cable attached to the EVM and check the FFT of the signal to see if there are any 50Hz tone?

    If the noise pickup is from the spo2 cable, then you will probably need to shield the cable from picking up noise from room lights or other instruments in the vicinity.

  • Hi Praveen,

    There was already no light in surrounding.

    I disconnected the cable and the 50Hz was gone.

    I shut down the Monitors, etc and disconnected them from power line. Now the Spo2 cable does not pick up any 50 Hz noise.