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Original question:

IWR6843: Phase shift in TX path

IWR6843: Beam switching between frames

Nimo1
Prodigy 20 points
Part Number: IWR6843

Hi,

Two quick questions regarding TX beam forming/beam steering in 6843 chip:

1- Is it possible to switch beam (or phase of channels) between frames?

2- How fast we can do beam switch (in terms of us, ms or in terms of fps)? 

Thanks

  • 0
    TI__Guru 50240 points

    Hi Nimo,

    I've asked an expert to look into this and we should have an answer for you in the next few days.

     

    Cheers,

    Akash

  • 0
    TI__Mastermind 40495 points

    Hi, there:

    Yes, the mmWave SDK support per profile based beam steering, and up to 4 subframes.  You can program different beam steering for different subframe. 

    An example for sub frame configuration is given below.  You can search each command details inside the mmWave SDK users guide at C:\ti\mmwave_sdk_03_03_00_03\docs\mmwave_sdk_user_guide.pdf

    profileCfg 0 61.0 10 6 135 0 14970880 2.5 1 256 2000 0 0 48
    profileCfg 1 61.0 10 6 135 0 10276864 2.5 1 256 2000 0 0 48
    profileCfg 2 61.0 10 6 135 0 6565888 2.5 1 256 2000 0 0 48
    profileCfg 3 61.0 10 6 135 0 1871872 2.5 1 256 2000 0 0 48
    chirpCfg 0 0 0 0 0 0 0 7
    chirpCfg 1 1 1 0 0 0 0 7
    chirpCfg 2 2 2 0 0 0 0 7
    chirpCfg 3 3 3 0 0 0 0 7
    advFrameCfg 4 0 0 1 0
    subFrameCfg 0 0 0 1 128 80 0 1 1 80
    subFrameCfg 1 0 1 1 128 80 0 1 1 80
    subFrameCfg 2 0 2 1 128 80 0 1 1 80
    subFrameCfg 3 0 3 1 128 80 0 1 1 80

    In the example above, different profile is given different phase shifting angle (marked in red), and all 3 TX antenna are transmit at the same time to achieve the beam steering.   

    The subframe period is set to 80ms in the above example.  You can modify the subframe periodicity to switch faster between sub-frames. 

    Another method is per chirp phase shifting.   You can program different chirp steering at different beam angle within one frame.  But then the Doppler FFT have to change for this type of configuration, that is why it is not supported yet in mmwave SDK.   But you can use DCA1000 + radar studio to do raw data capture using this mode and do post processing offline. 

    Best,

    Zigang

  • 0 in reply to zigang Yang
    Prodigy 20 points

    Awesome,

    Thank you for your quick response.

    Very helpful