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ADS1294R: Amplitude Inaccuracy at 8000 SPS in HR mode.

Santosh Kumar
Prodigy 20 points
Part Number: ADS1294R

Hi,

We are trying to acquire the ECG signal at 8000 SPS in HR mode, we are observing amplitude inaccuracy approx. +16% which is failing as per IEC 60601-2-47 (<5%).

We are able to get acceptable amplitude accuracy from 250~4000 SPS, but it is failing at 8000 SPS.

HR Mode; Gain =4 ; VREF=2.4V;  WCT_CHOP=Variable Chopping Frequency; WCTA/B/C = Enabled ; CLK= Internal Oscillator.

Please let us know if any setting or changes we need to do for getting accurate amplitude at 8000 SPS.

Regards,

Santosh

  • 0
    TI__Mastermind 19815 points

    Hi,

    Are you using the evaluation kit/board(EVM) or customer board in a product?

    What was the signal source(s)? Do you use an ECG simulator?

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

    May I ask what do you mean and how you calculate the "acquire the ECG signal at 8000 SPS in HR mode, we are observing amplitude inaccuracy approx. +16%?

    especially what do you mean and how do you calculate the accuracy?

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

    Have you tried the similar configurations with the EVM and an ECG simulator?

    Do you use the RLD?

    Do you use/enable the any of the Respiration and/or the AC lead off detection?   If yes, could you turn off/disable them to see whether the accuracy improves?

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

    Note:

    Signals integrity and performances and accuracy heavily depend on, but not limited to the following sources and factors -
    environment noises, EMI, electrodes, cables, gels, skin conditions, external circuits, board designs, RC/integrator circuit tuning, experiment setup,
    body, breathing, air in lung, walking/talking, skin conditions, environmental surroundings ,etc.

    A product design depends on many factors, variation, here are just listing some examples -

    electrodes, subjects' skin conditions, mechanical, enclosures, materials, surroundings and environments.

    Products'/systems power supplies, PCBAs, mechanical, chassis, shielding, grounding, enclosures designs, data transmission cables to computer, computer and/or any other power adapters, and the operating/usage environments.

    Then, when contacting with human, results depend on electrodes/patches materials/conditions, cables/wires materials/lengths, gels, skin conditions, body, breathing, air in lung, walking/talking, etc.

    Thanks