Hi,
I am currently working with the ADPD6000 Kit for PPG signal acquisition (Green, Red, IR).
Observed Behaviour:
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The PPG waveform polarity is not constant
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The signal:
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Sometimes appears as expected (systolic peak upwards)
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Sometimes appears inverted (systolic peak downwards)
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More importantly:
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The inversion can change during runtime
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It is also different across subjects and even between hands of the same subject
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Example:
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Red LED appears consistently inverted for some subjects
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Green LED may be inverted on one hand but not the other
This behaviour makes it difficult to rely on simple post-processing inversion.
Questions:
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What could cause dynamic polarity inversion in PPG signals on ADPD6000?
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Are there recommended register settings or debugging methods to ensure stable polarity?
Could you please suggest:
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Possible root causes
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Debugging steps (register-level if possible)
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Recommended signal conditioning approach
Thanks in advance!