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Original question:

IWR6843ISK: Boot Up mmWave Studio 2.1.1.0: Unable to load DLL 'RadarLinkDLL.dll': The specified module could not be found...

IWR6843ISK: FMCW Radar Equation

Daniel Areñas Mayoral
Prodigy 50 points
Part Number: IWR6843ISK

Tool/software:

Greetings,

 

I have been working with IWR6843ISK and I am trying to understand the radar equation applied to this system. For that reason I have been reading https://www.ti.com/lit/an/swra553a/swra553a.pdf. In section 2.1.1 the radar equation is explained and I understand all the components except the the Number of chirps and the Chirp time. I understand that the chirp time is the inverse of the bandwidth used in the receptor when running the FFT, but for short times this bandwidth is smaller than the actual bandwidth of the receptor, in this case for IWR6843ISK the minimum bandwidth is 175KHz, so if my chirp is 40 us, the bandwidth in the radar equation would be 25 KHz.  On the other hand, I don't understand why the number of transmitted chirps affects the range, since in theory the FMCW radar is transmitting all the time. I can imagine that the principle behind is related to the pulse radar when many pulses are transmitted and illuminate a target, but in those cases there is an efficiency term that is not considered in this paper.

Thank you very much for your help,

Best Regards,

Daniel

  • 0
    TI__Genius 11900 points

    Hi

    Thanks for your query. Please allow us a couple of days to respond

    Regards

  • +1 in reply to Abhishek Karkisaval
    TI__Mastermind 37805 points
    Daniel Areñas Mayoral said:
    On the other hand, I don't understand why the number of transmitted chirps affects the range, since in theory the FMCW radar is transmitting all the time.

    The number of transmitted chirps affects the detection range because the FMCW radar is not truly transmitting all the time. In a single frame, the radar transmits some number of chirps. Each chirp combines together to improve the SNR of the measurement. I think of it like having 1 long chirp that lasts 256 usec, or 4 chirps that last 64 usec each. Both situations have the same amount of integration time, so their SNR estimates should be the same (assuming coherent doppler integration, which is how the 6843 OOB demo works)

    Best

    Nate

  • 0 in reply to Nathan Block
    Prodigy 50 points

    Dear Nathan,

    Thank you very much for your response. I understand what you mean, so it is the integration time of the radar what is used, so the more chirps on a frame the higher SNR. And the frame rate should be the number of chirps transmitted *Chirp time right ? 
    Lastly, could you please enlighten me about the chirp time and the bandwidth question please ?

    Thanks a lot.
    Best regards,

    Daniel