IWR1443: clutter removal when only one chirp/frame is used

Hi Akash,

Thank you for the information. I reviewed the user guide for the high accuracy app. Yes, maybe I got off on the wrong track. Perhaps you can re-direct me. I had thought that is was the way to go since I was only interested in range and being able to provide rapid range data (frame rate > 100 Hz). I thought that no velocity and aoa calculations would be advantageous for a faster rep rate. I then realized that I should have clutter removal and realized that the high accuracy approach did not support it since the oob demo used the chirp train which provides the velocity information.

I will re-examine using only one transmit and one receive antenna to improve the frame rate but I think the frame rate is heavily dependent upon the number of chirp loops (the number of chirps in a frame). The frame rate to my understanding is (not considering the gui's uart time which will not be in the final application, I will have a gpio as an event notifier)

chirp_cycle_time=idle_time+rampEndTime
numChirpsPerFrame=numTxAnt*num_chirp_loops
chirping_time=numChirpsPerFrame*chirp_cycle_time
fps=1/chirping_time

This does not reflect any processing time and no consideration for duty cycle to let the transmitter cool off. Also I have not accounted for the number of receive antennas. I suppose I would replace numTxAnt with numTxAnt*numRcAnt=numVirtualAnt. Any guidance on these topics is appreciated.

You made a comment that the clutter removal is dependent upon the second fft. The following code segment indicates that this is not the case (main.c):

Load_update();
dataPathObj->timingInfo.interFrameCPULoad=Load_getCPULoad();

MmwDemo_dataPathWait1D(dataPathObj);
/* 1st Dimension FFT done! */

Load_update();
dataPathObj->timingInfo.activeFrameCPULoad=Load_getCPULoad();

/* Clutter removal */
if (dataPathObj->cliCfg->clutterRemovalCfg.enabled)
{
int32_t rngIdx, antIdx, dopIdx;
cmplx16ImRe_t *fftOut1D = (cmplx16ImRe_t *) dataPathObj->radarCube;
cmplx32ImRe_t meanVal;

for (rngIdx = 0; rngIdx < dataPathObj->numRangeBins; rngIdx++)
{
for (antIdx = 0; antIdx < dataPathObj->numVirtualAntennas; antIdx++)
{
meanVal.real = 0;
meanVal.imag = 0;
for (dopIdx = 0; dopIdx < dataPathObj->numDopplerBins; dopIdx++)
{
meanVal.real += fftOut1D[rngIdx*(dataPathObj->numDopplerBins*dataPathObj->numVirtualAntennas) +
antIdx + dopIdx*(dataPathObj->numVirtualAntennas)].real;
meanVal.imag += fftOut1D[rngIdx*(dataPathObj->numDopplerBins*dataPathObj->numVirtualAntennas) +
antIdx + dopIdx*(dataPathObj->numVirtualAntennas)].imag;
}
meanVal.real = meanVal.real/dataPathObj->numDopplerBins;
meanVal.imag = meanVal.imag/dataPathObj->numDopplerBins;
for (dopIdx = 0; dopIdx < dataPathObj->numDopplerBins; dopIdx++)
{
fftOut1D[rngIdx*(dataPathObj->numDopplerBins*dataPathObj->numVirtualAntennas) +
antIdx + dopIdx*(dataPathObj->numVirtualAntennas)].real -= meanVal.real;
fftOut1D[rngIdx*(dataPathObj->numDopplerBins*dataPathObj->numVirtualAntennas) +
antIdx + dopIdx*(dataPathObj->numVirtualAntennas)].imag -= meanVal.imag;
}
}
}
}

MmwDemo_process2D(dataPathObj);
/* 2nd Dimension FFT done! */

To improve my frame rate, I would reduce the numVirturalAntennas to 1 and do not perform MmwDemo_process2D since I am not interested in velocity or aoa data. Again, your thouhts.

Thanks.

Al

Hi Akash,

I have sent you post regarding your reply. Do you have anything to add?

Thanks.

Al