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IWR6843ISK-ODS: Definition of CFAR Threshold scale

Smart Fountain
Intellectual 320 points
Part Number: IWR6843ISK-ODS

Hi,

I have a few questions about cfar threshold scale.

Q1

In the MMWAVE SDK User Guide section 3.4 Configuration (.cfg) File Format, Threshold scale.parameter of cfarCfg command is defined as following.
----
Tcli = 512 x TdB / 6 x N / N'
where N is numVirtualAntennas
----

In the case of using "\ti\mmwave_industrial_toolbox_3_4_0\labs\lab0020_pplcount_Overhead\GUI_A_base_no_logic"
what is the value of the N (numVirtualAnntennas) ?


Q2

In the case of using " \ti\mmwave_sdk_03_01_01_02\packages\ti\demo\xwr68xx\mmw\xwr68xx_mmw_demo.bin"
is the value of N same as lab0020 ?

It seems that cfar function is not same module for lab0020 and SDK. (it seems done on DSP for lab0020, HWA for SDK)

Best regards,
Fountain

  • 0
    TI__Mastermind 28055 points

    Hi Fountain,

    For ODS demo (lab 20), there are 12 virtual antennas. (3 Tx by 4 Rx). 

    For OOB demo, number virtual antennas depends on the configuration.

    Regards,

    Justin

  • 0 in reply to Justin Curewitz
    Intellectual 320 points

    Hi Justin,

    I understood that number of virtual antenna is 12 for lab20, and also it depends on the other configurations for OOB demo.

    (1) Can I confirm that the calculation of the threshold for lab20 and OOB demo are the same ?

    (2) The default value of the Tcli is 7120 for lab20 configuration.

    According to the equation, the threshold TdB is

    TdB = Tcli / 512 * 6 * N' / N = 7120 / 512 * 6 * 16 / 12 = 111.25 dB

    It is felt that 111.25 dB is such a huge number, is it the right value ?

    Best regards,

    Fountain

  • 0 in reply to Smart Fountain
    TI__Mastermind 28055 points

    Hi Fountain,

    Lab20 calculation is the same as SDK 1.2.0.5 OOB demo.  Signal chain has been used from that demo to provide point cloud to the tracker in lab0020.

    For the new SDK OOB demos, the threshold is different - for example, entering 12 is 12 dB. 

    For the dB calculation in lab0020 - from the SDK 1.2.0.5 documentation, we need to look at the xwr16xx calculation, so

    Tcli = 256 * numVirtualAntennas * TdB/6 then TdB = 6*Tcli/(256*numVirtualAntennas) = 7120*6/(256*12) = 13.9 dB

    Regards,

    Justin

  • 0 in reply to Justin Curewitz
    Intellectual 320 points

    Hi, Justin,

    Thank you for your reply. I understood.

    By the way, how can I know which is the reference documentation for each lab ?

    Best regards,

    Fountain

  • 0 in reply to Smart Fountain
    TI__Mastermind 28055 points

    Hi Fountain,

    Each lab has a user's guide.  Besides that, we are updating other documents in TIREX to support all people counting demos. Demos are in the process of being moved to newer SDK architecture to alleviate the issue you faced.

    Regards,

    Justin