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Original question:

IWR6843ISK: what is the elevation resolution ?

IWR6843ISK: Elevation angle resolution issue

Cagri Tanriover
Intellectual 885 points
Part Number: IWR6843ISK

Hi,

It is mentioned in the following thread that the elevation FoV is 44 degrees while the elevation angle resolution is 58 degrees.

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/784351/iwr6843isk-what-is-the-elevation-resolution

I am trying to make sense of these figures from a practical perspective and things don't make sense. According to my understanding, based on the elevation FoV angle of 44 degrees, no two objects (at the same range and the same velocity) separated by more than 44 degrees in the elevation dimension can be detected by the radar at the same time. Therefore, even if two objects are separated by 58 degrees in the elevation direction and one of those objects is within the elevation field of view, the other one will not be detectable anyways. So the elevation resolution seems to be a redundant measure in this example.

What this tells me from a practical perspective is, if two objects (at the same range and velocity) are within 44 degrees or less with respect to each other along the elevation direction, they cannot be differentiated at all. In other words, trying to differentiate two such objects within the elevation FoV using IWR6843ISK device is not possible.

Can you please confirm and if my understanding is not correct, can you please elaborate using real world examples of how this would work?

Thank you for your help.

Regards,
Cagri

  • 0
    TI__Mastermind 36485 points

    Hi, Cagri:

    Yes, if the two subjects falls into same range bin and same Doppler bin, and can not separate in azimuth angle as well, then yes, they probably will not be able to separate in elevation.   But if these two objects can separate by range, or Doppler or azimuth, then the elevation estimation accuracy can be still good. Because angle accuracy is a function of SNR as well as a function of angle resolution.    

    Hope it makes sense to you.  Most of the case, target are already separated by range, and Doppler.  

    Best,

    Zigang

  • 0 in reply to zigang Yang
    Intellectual 885 points

    Hi Zigang,

    Thank you for your insights. I have one more clarifying question based on your following statement:

    "But if these two objects can separate by range, or Doppler or azimuth, then the elevation estimation accuracy can be still good. Because angle accuracy is a function of SNR as well as a function of angle resolution."

    Does this mean if I get good separation say by range between two objects, it may be possible to get accurate elevation separation below the stated 58 degrees? In other words, 58 degrees of elevation resolution is not a hard lower limit but depends on the SNR in a detection scenario. Is this true?

    Regards,

    Cagri

  • +1 in reply to Cagri Tanriover
    TI__Mastermind 36485 points

    HI, Cagri:

    If you can separate the two targets by range, then they are all ready separated.  You will likely to estimate the angle for two different range, so there is no elevation separation needed here.   Again angle separation only involves when two targets falls into same range bin, and same Doppler bin. 

    On the other hand, If there are two targets falls into the same range bin, and same Doppler bin, (the angle difference is smaller than azimuth angle resolution and elevation angle resolution), then regular Bartlett beamforming will not be able to separate the two targets ((even the SNR are strong).  But if advanced angle algorithm, like MUSIC, is used, there are still chance to separate them.   

    Best,

    Zigang