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AWR6843AOP: Relationship with FFT size and number of Output sample

JINHYUN JEONG
Prodigy 200 points
Part Number: AWR6843AOP
Other Parts Discussed in Thread: AWR1843

Tool/software:

Dear, Ti Experts.

Hello

i am using HWA module to do FFT on radar signal.

What is the result if i set hwa parameter as like below. 

"""""""""""""""""""""""""""""

Input sample :32

FFT size : 32

Output sample : 1

""""""""""""""""""""""""""""""

FFT size : 5 ( math expression : 32)

SrcAcnt : 31 (32)

DstAcnt : 0 (1)

From my mathematical knowledge, i know that the output sample is same with FFT size.

However, when i checked the results(only one output sample) , it seems that the average of 32 output samples is output.

Thanks

Best regards

JINHYUN JEONG

  • 0
    TI__Mastermind 36725 points

    Hi, Jinhyun:

    Please let me know what you are trying to achieve.  Your question is vague.  I need to know what you are trying to achieve, and what problem you have.

    Best,

    Zigang

  • 0 in reply to zigang Yang
    Prodigy 72 points

    Hello Yang,

    I also have a similar vague question.

    I am using AWR1843. I can only adjust number of adc samples with profileCfg.<numAdcSamples> as stated in mmwave sdk user guide.

    I need to know if this is directly the FFT size or FFT size is independent of the <numAdcSamples>.

    I need to know because we are studying on an academic article

    I could not found the FFT size in the documents.

  • 0 in reply to adem sahin
    TI__Mastermind 36725 points

    HI, there:

    FFT size in the HWA has to be power of 2.  So if the numAdcSamples are already a power of 2, then the FFT size will be the same as numAdcSamples.  If not, then FFT size will be the closest power of 2 what is larger than the numAdcSamples.  For example, if numAdcSamples is any number between 129 ~ 256, the FFT size will be 256. 

    Best,

    Zigang