IWRL6432BOOST: Is the FFT performed with the HWA real FFT or complex FFT and is fftshift required to arrange the frequency components?

Padmanabhan K

Part Number: IWRL6432BOOST

Since the data received from the ADC is only real values, so does the HWA performs complex FFT and gives symmetrical output or performs only real FFT? Does the output requires FFT shift to arrange the frequency components or already it is applied?

over 2 years ago

0 Nathan Block over 2 years ago

TI__Mastermind 37805 points

Hi,

We're investigating this now. Thank you for your patience. We will have a response by tomorrow.

Best,

Nate

+1 Nathan Block over 2 years ago in reply to Nathan Block

TI__Mastermind 37805 points

Hi,

The FFT in HWA is complex by nature. So for real ADC samples case the imaginary part in the FFT core is set to zero. We configure input as real:

hwaParamCfg.source.srcRealComplex = HWA_SAMPLES_FORMAT_REAL;

Then on the output side we output only the first half of the range FFT:

hwaParamCfg.dest.dstAcnt = pDPParams->numRangeBins-1;

where numRangeBins is set to half of rangeFftSize.

And of course we configure the FFT size as the log2 of the size:

hwaParamCfg.accelModeArgs.fftMode.fftSize = mathUtils_ceilLog2(pDPParams->rangeFftSize);

All code referenced can be found in rangeprochwa.c.

Best,

Nate

0 Padmanabhan K over 2 years ago in reply to Nathan Block

Prodigy 165 points

Thanks a lot for your answer.

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IWRL6432BOOST: Is the FFT performed with the HWA real FFT or complex FFT and is fftshift required to arrange the frequency components?