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ADS1298 modulated noise

Al Luis
Prodigy 225 points
Other Parts Discussed in Thread: ADS1298

Hello, I am using ADS1298. When I conect an input signal it appears a multiplicative modulated noise in the output.

When I do the FFT on matlab it appears the noise components around 50 Hz, 100 Hz, 150 Hz....  Like an AM modulation...

What could be the reason of this?

I show you the pictures :

This is the FFT when my input signal is a 8Hz 100mVpp from the signal generator

and this is the same signal in time domain:

Please help me.

Thank you very much.

  • 0
    TI__Guru 66446 points
    Hi Al - Welcome to our forum!

    I would assume that this noise is coming from your 50Hz main power lines. The ADS1298 will not reject 50Hz/60Hz power line noise on its own, so this is typically filtered out in the digital domain using (very) high-order notch filters.

    Check that your grounding is sound. If you can operate your system from DC battery power, that would be best. Additionally, you might try shielding your setup to reduce how much 50Hz noise couples into the system from the surrounding lighting.

    Best Regards,