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Original question:

IWR1843: Export data of Scatter plot and Range Profile

IWR6843AOPEVM: Range profile acquisition with Matlab

Fabien Berland
Prodigy 90 points
Part Number: IWR6843AOPEVM
Other Parts Discussed in Thread: DCA1000EVM, MMWAVEICBOOST

Hi,
I am using an IWR6843AOPEVM and I would like to acquire the range profile information with Matlab but without DCA1000EVM or MMwaveICboost.
To do this, I start with the area_scanner_visualize demo that is available in the labs.
I understood that it was necessary to change the cfg file to ask the sensor to send the distance profile but then I do not understand how to transform the information received into dB values to display the profile.

Can you help me ?

  • +1
    TI__Mastermind 37805 points

    Hi Fabien,

    I would recommend using the out-of-box demo for instead of the area scanner. You can get the range profile out by setting the third field in guiMonitor equal to 1, as explained on page 25 of the mmwave_sdk_user_guide, probably found under C:/ti/mmwave_sdk_03_05_00_04/docs/mmwave_sdk_user_guide.pdf on your computer.

    Once you can see the range profile using the online visualizer tool,  You can export the data out using the information in the Understanding OOB UART Data page in the mmwave TIRex page. You'll want to extract the Range Profile, which is in log2 magnitudes displayed in Q9 (7 digits for integer, 9 digits for fraction) format. You can convert that to dB by taking (10*log10(2^x)) if the result x.

    Best,

    Nate

  • 0 in reply to Nathan Block
    Prodigy 90 points

    Thank you Nathan for that answer,

  • 0 in reply to Nathan Block
    Prodigy 90 points

    Hi,
    I can get the range profile but I have a problem with the values when I compare them to those obtained with the visualizer.
    I think, I'm not processing the bits correctly.
    A range profile value is encoded on 2 bytes. So, what I have to do to find a value, is to take the first sevent bits as the interger part and the last 9 bits as the fractionnal part. The decimal value is then obtained by transforming the integer part from base 2 to base 10. For the fractionnal part it is the same thing but it is the same thing but after having obtained the value in base 10 we divide by 2^9, isn't it ?
    If this process is correct,  I think that my mistake may come from the order in which I take the bits. Does the first bit of the group of two bytes correspond to the most significant bit? Is there a document explaining the order of sending data for the distance profile?

    And I have another question: what is the best solution to find the distance in meters corresponding to each value in dB ?

  • 0 in reply to Fabien Berland
    TI__Mastermind 37805 points

    Hi Fabien,

    Please open a new thread when you have a new question. This helps us keep E2E organized better so future customers can easily search for answers when they have similar questions. I will gladly answer this question in a new thread.

    Best,

    Nate