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IWR6843AOP: CFAR threshold and minimum value of magnitude detection

user6220621
Prodigy 190 points
Part Number: IWR6843AOP

Hi everyone,

I am working with the SDK 3.2.0.6.AOP and the IWR6843AOP radar on the configuration file and more precisely on the CFAR parameter.

I would like to calculate the 'trigger' thanks to the cfar threshold value.

I read in the user guide this calcul (following) but I am not sure that this one is the answer I am looking for and neither what are the parameters corresponding to in this calcul (MMWAVE SDK User Guide p.28):

CUT > (Threshold scale converted from dB to Q8) + (noise sum / 2^x)


To sum up, if I put 15 as range cfar threshold, I would like to know the minimum value of the CUT which will detect an object (by looking the graph, it seems that for a threshold = 15dB, we have something close to 3000 in magnitude as a minimum value of detection.)

How could I calculate this minimal value of magnitude and how could I find the parameters needed to calculate it?

Thanks by advance,

Have a good day!

  • 0
    TI__Mastermind 30405 points

    Hi Melanie,

    Please look at the following thread:

    IWR1443BOOST: CFAR Threshold format clarification

    CFAR works on a relative difference between the Cell Under Test (CUT) and it's neighboring cells as defined by the CFAR type and configuration (Threshold, Window Size and Guard Length).

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    Prodigy 190 points

    Thank you Nitin,

    If I well understand, if I put (for exemple) 15 as CFAR Threshold, I will get a "TCLI" as a result of a calcul with the threshold ( = 15dB ) and this TCLI will be add to the 'surrounding noise average' and if the reflection of the CUT is higher than this result, it will be considered as an object ? 

    Thank you by advance!

  • 0 in reply to user6220621
    TI__Mastermind 30405 points

    Hi Melanie,

    Conceptually yes, but please note that SDK 3.x uses the threshold directly in dB. So the peak value for the CUT is converted to Log and then compared against the specified CFAR criteria.

    For example,with reference to the DSP based implantation, please look at the following functions in the CFAR DPU

    C:\ti\mmwave_sdk_03_04_00_03\packages\ti\datapath\dpc\dpu\cfarcaproc\src\cfarcaprocdsp.c

    DPU_CFARCAProcDSP_process()

    ---> CFARCADSP_processRangeDomain()

           ---->CFARCADSP_cfarCadB_SOGO()

    CFAR DPU doxygen documentation: C:\ti\mmwave_sdk_03_04_00_03\packages\ti\datapath\dpc\dpu\cfarcaproc\docs\doxygen\html\index.html

    Regards

    -Nitin