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AWR1843: Is there a limit on the maximum down frequency modulation slope in the idle time setting of chirp

Geogia
Prodigy 170 points
Part Number: AWR1843

Hi experts,

I would like to inquire about the setting of idle time for chirp. Is there a limit on the maximum down frequency slope?  If so, is it the same as the maximum limit of<freqSlopeConst>?

In the "Programming Chirp Parameters in TI Radar Device"I only found the explanation  as shown in the figure below and which does not mention the slope of down frequency modulation. So I would like to confirm with you.

Thanks in advance. 

  • 0
    TI__Genius 13046 points

    Hey Geogia,

    Thanks for reaching out to us regarding your question. Could you clarify on whether you're referring to the synthesizer ramp down settling time/synthesizer ramp down frequency - i.e. what is referenced under 5.1 Idle Time - or the chirp frequency slope?

    Regards,

    Kristien

  • 0 in reply to Kristien Everett
    Prodigy 170 points

    I mean chirp frequency slope, thanks.

  • 0 in reply to Geogia
    TI__Genius 13046 points

    Hey Geogia,

    For 77 GHz devices, like the AWR1843, the range for chirp frequency slope is limited to ±266 MHz/μs. For 60 GHz devices, the range for chirp frequency slope is limited to ±250 MHz/μs. This can be found under Table 5.24, p. 83 of the mmWave Radar Interface Control Document (rev. 2.23); this document can be found by navigating to the mmWave-DFP download page on TI.com, clicking on download options, and selecting the corresponding PDF under Documentation. If you've already downloaded the DFP, you can find the document under ti/<mmwave-dfp-version>/docs.

    Let me know if you have any other questions.

    Regards,

    Kristien

  • 0 in reply to Kristien Everett
    Prodigy 170 points

    Hi Kristien, I am using AWR1843 and 2944. When the frequency of CHIRP drops, as I noted in the figure, is it necessary to calculate the fall time according to the -266 MHz/μs limit? And add this fall time to idle time in profileCfg?

  • 0 in reply to Geogia
    TI__Genius 13046 points

    Hey Geogia,

    As mentioned in the "Programming Chirp Parameters in TI Radar Device" document, I would recommend using the Ramp Timing Calculator built into mmWave Studio 2.1.1 to determine the idle time for the profileCfg. This will give recommendations for different timing parameters depending on chirp slope, number of ADC samples, and sampling rate. Calculated parameters for higher settling percentages provide more reset time for the synthesizer and more consistent performance, but it may be more difficult to tune other chirp parameters.

    Let me know if you have any other questions.

    Regards,

    Kristien