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Original question:

IWR1443BOOST: some related question about IWR 1443 signal

IWR1443BOOST: Range Resolution confusion (IWR1443Boost EVM)

Abdelwahed KHamis
Prodigy 60 points
Part Number: IWR1443BOOST

I set the the EVM to the following configuration 

which should allow range resolution of 4.2 cm, right?

However the plots show range bins spaced by about 2.3 cm (example screenshots below) ! better than allowed by IWR1443Boost according to my understanding. 

How could this happen? any explanations

  • 0
    TI__Guru 50240 points
    Hi Abdelwahed,

    So I think there is confusion on the difference between resolution and accuracy. What you are thinking is likely the accuracy of the sensor which can be accurate to within <1 mm in some instances.

    Resolution refers to the minimum range between two objects in order for the sensor to distinguish they are two distinct objects. This number is is constrained by chirp bandwidth and as a result cannot be improved to better than 2.5 cm.


    Let me know if you have more questions.


    Cheers,
    Akash
  • 0 in reply to Akash Gondalia
    Prodigy 60 points

    Thanks Akash for your response

    I understand that millimetre level motion can be tracked using the EVM and I am asking about range resolution ( minimum range between two objects as you put it)

    the question is concerning the best resolution. You are saying that the best value is 2.5 cm and the plots above is about 2.3 cm ! 

    Also, how this is calculated ? as the chirp width can be 5Ghz in 1443Boost, does this make the best resolution 299792458/(2*5000000000)  = 0.029 meters (according to equation 9 below)?

  • 0 in reply to Abdelwahed KHamis
    TI__Guru 50240 points
    Hi Abdelwahed,

    What you are referring to is accuracy, not resolution. Resolution is going to be mostly fixed as a result of the chirp bandwidth, although there are a variety of ways to improve accuracy.


    Cheers,
    Akash
  • 0 in reply to Abdelwahed KHamis
    TI__Expert 5320 points
    Hi Abdelwahed

    if you look at the profileCfg command that is sent to the device for this config, I believe it is same as what I see on my setup:

    >>profileCfg 0 77 442 7 72.73 0 0 55 1 144 2224 0 0 30

    The numAdcSamples in the above config is 144 which will result in a Range FFT size of 256. As Akash mentioned, this is what causes the range accuracy to be better than the range resolution.

    So rangeAccuracy or the rangeStep that can be seen on the rangeProfile plot (i.e. output of 1D FFT for the first chirp) is (0.042*144/256)=0.023625 which is roughly what you see in the Visualizer.

    Hope this clarifies further for you.

    -Madhvi