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IWR6843AOP: What do the parsed TLV timestamps refer to?

Minghui Ye
Prodigy 30 points
Part Number: IWR6843AOP

Tool/software:

Hello,

I am using IWR6843AOP for vital signs detection and after extracting values in the recorded .json file for the frames, I found the timestamps intervals vary a lot and they seem to have minimum difference of 14. However, according the chirp configuration I used, the frame periodicity should be 90ms, which means the timestamps intervals should be 90ms *n. I don't understand why would this extremely small intervals happen, assuming this could be caused by periodicity inconsistency that happens probably among certain amount of frames recorded. It would be really appreciated if someone can help me understand this phenomenon. 

Thanks !

Kind regards,

Minghui

  • 0
    TI__Genius 11900 points

    Hi

    Vital signs TLV update rate will be much slower than the normal point cloud TLV. Point cloud TLV will be sent every frame but vital signs TLV depends on the update rate of the vitals. This could range from 5s. Past 20s data is considered for the current computation of vitals. Hence, Vitals TLV update will be much slower.

    Regards

  • 0 in reply to Abhishek Karkisaval
    Prodigy 30 points

    Hi Abhishek,

    I understand that the vital sign point clouds are re-calculated every 15 frames, but my question is even when I put all the point cloud TLVs together, I still observe timestamp intervals which are smaller than 90ms. The 90ms timestamp interval is determined by the configuration file intuitively, however, a very small amount of timestamp interval during my 7-minutes json file are in smaller values, some are even as small as 14. That's something I don't understand. Is it a kind of inconsistency  (bias?maybe) of frame periodicity during a long range of time? 

    Thanks.

  • 0 in reply to Minghui Ye
    TI__Genius 11900 points

    Hi

    Timestamp could be artefact of the PC. The device sends the uart data out of the device at the frame rate. UART task itself is called once per frame at the end of all the processing.

    Regards