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IWRL6432AOP: Regarding c_NumOfChirpsAccum in rl_sensFrameCfg

user4810817
Intellectual 301 points
Part Number: IWRL6432AOP

Tool/software:


I would like to confirm whether increasing c_NumOfChirpsAccum leads to more chirps being transmitted as RF signals from the Tx antenna.
The manual includes the following description:

Section: Calculating Burst and Frame Period
Total Number of Chirps in a Burst = h_NumOfChirpsInBurst × max(1, c_NumOfChirpsAccum)

Does "Total Number of Chirps in a Burst" refer to the number of chirps transmitted as RF signals during the burst period?

[Example]
If c_NumOfChirpsAccum = 4 and h_NumOfChirpsInBurst = 8,
then Total Number of Chirps in a Burst = 32.
Does this mean that 32 chirps are transmitted as RF signals during the burst period?

[Referenced]
MMWAVE_L_SDK_05_05_03_00
mmwave_dfp_interface_control_document.pdf

  • 0
    TI__Mastermind 23177 points

    Hello,

    A burst is just a series of chirps, and the number of chirps accumulated does NOT increase the number of chirps.

    Best Regards,

    Pedrhom

  • 0 in reply to Pedrhom Nafisi
    Intellectual 301 points

    Dear Mr. Nafisi,

    Thank you very much for your response.
    Based on the information you provided, I understand that increasing c_NumOfChirpsAccum does not result in an increase in the number of chirps transmitted from the RF.
    With that in mind, I would like to ask an additional question, as there may be a discrepancy in the manual.

    Why is TotalNumChirps described in the manual as h_NumOfChirpsInBurst multiplied by max(1, c_NumOfChirpsAccum)?
    My understanding is that TotalNumChirps = h_NumOfChirpsInBurst, so I would like to confirm whether this might be a documentation error？

  • 0 in reply to user4810817
    TI__Mastermind 23177 points

    Hello,

    I see the confusion here. The analog front end does physically emit more chirps, but then the extra chirps are accumulated and averaged before being passed onto the digital end that does the processing. The extra chirping provides a higher SNR without an increase in processing load. The DFP/firmware revolves around the antenna and analog portions of the radar sensor pipeline, while the SDK and example demos revolve around the cpu cores and digital portions of the radar sensor pipeline.

    Best Regards,

    Pedrhom

  • 0 in reply to Pedrhom Nafisi
    Intellectual 301 points

    Thank you for your explanation.
    Just to clarify, does c_NumOfChirpsAccum cause the RF to emit more physical chirps, even though the digital processing only sees the averaged result?

    If so, then the manual's formula TotalNumChirps = h_NumOfChirpsInBurst × max(1, c_NumOfChirpsAccum) makes sense from a physical transmission perspective.

    Could you please confirm whether this formula refers to the number of physical chirps emitted or the number of chirps processed digitally?

  • 0 in reply to user4810817
    TI__Mastermind 23177 points

    You are correct. The formula is for physical chirps emitted. To reiterate, that formula comes from the Interface Control Document, which is for the DFP and is a representation of the function calls for the analog front end.

    Later on, when looking at the software SDK which is for the digital ARM core and example demos, completely separate from the DFP, you may not see the mention of chirps accumulated because it is averaged out by design.

    Best Regards,

    Pedrhom