• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 48 subscribers
  • Views 477 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AFE4404: motion and ambient light changes

CYL
Prodigy 50 points

Part Number: AFE4404

Hi,

 

From AFE4404 datasheet, what does it mean in yellow paragraph below?

Does it means on the design need to take care on the motion and ambient light changes, the TI IC cannot filtered such noise?

9.2.1 Design Requirements The AFE architecture is very flexible, and can be used for both high-performance saturation of peripheral capillary oxygen (SpO2) applications as well as low-power, battery-operated heart-rate monitoring (HRM) applications as a result of this flexibility. The high dynamic range of the AFE enables excellent SNR for the signal of interest (usually small in amplitude) even in the presence of large-signal artifacts resulting from ambient and motion changes.

 

9.2.2 Detailed Design Procedure

The following important factors are key to extracting the full performance benefit from the AFE: 1. Good optics including bright LEDs and high-sensitivity photodiodes 2. Good mechanical design 3. A calibration loop that sets the optimal AFE settings based on the signal conditions

TI recommends that a system-level budgeting of dynamic range be initially done based on the following factors: 1. The range of the dc signal currents that are input to the AFE 2. The range of ac-to-dc ratio across different users 3. Signal current changes expected from artifacts (such as motion and ambient light changes) 4. The SNR required for heart-rate extraction algorithms to function successfully Based on the above analysis, the available dynamic range from the AFE (approximately 100 dB) can be partitioned

Thanks

  • 0
    TI__Genius 12575 points
    Hi Jayue,

    The PPG signal's quality will differ from user to user, so a calibration routine is needed that dynamically adjust the AFE's parameters to acquire a better signal from any given individual.
    The highlighted paragraphs talks about all the factors that should be considered while writing the calibration routine such a change in ambient light, disturbance due to motion, DC of the received signal etc.

    Regards,
    Prabin