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ADS1192: Problem of QRS distortion at R points

İnanc Mert Altun
Prodigy 20 points
Part Number: ADS1192

Tool/software:

Hello,

We use the ADS1192 sensor. We get ECG records with this sensor. In the tests we perform, there are distortions in the R points in the ECG signals. Only the R point is distorted and it only occurs in Lead 2. While there is no distortion in Lead 1, the fact that this situation only occurs in Lead 2 makes us suspect that there is a problem with the sensor. I am sharing the relevant images below.
Also, data rate = 500 SPS

If you want to see detailed configuration information or schematics, we can share them.

  • 0
    TI__Guru 66566 points

    Hi Inanc,

    Thank you for your post. 

    It looks like the amplitude of the signal is larger on Lead II than Lead I and may be exceeding the ADC full-scale. What is the gain that you have configured in the PGA for that channel? Can you try reducing it?

    Regards,

    Ryan 

  • 0 in reply to Ryan Andrews
    Prodigy 20 points

    Channel gain 6 PGA.
    Reference voltage 4.24V.

    What could be the problem?

  • 0 in reply to İnanc Mert Altun
    TI__Guru 66566 points

    At the moment, I'm not sure if the amplitude of the waveform is scaling correctly (ignoring the R-peak glitch for now). Can you configure all channels to use the internal square wave test signal? This should give a consistent amplitude for all channels.

    Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Prodigy 20 points

    This ECG graph was taken using a simulation device. The amplitude of the signal produced by the simulation device for Lead 1 is low. In other words, the reason why the amplitude of Lead 1 is low is the simulation device.

    But this is not the problem for us.
    The problem is the distortions in the R points.
    What can you say about these distortions in the R points? What do you think could be the reason for this error in the R points?

  • 0 in reply to İnanc Mert Altun
    TI__Guru 66566 points

    Hi Inanc,

    I understand the simulation device is controlling the output signal amplitude. Is it possible to scale the output of the simulator to a lower amplitude and check if the problem is consistent?

    Alternatively, can you replace the simulator with a function generator and configure it for a sine wave output (i.e. try 200mVpp, mid-supply common-mode voltage).

    Regards,

    Ryan