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AWR1642BOOST: Decreasing 1D FFT value of reflector as it is moved closer

Avinash Kondeppady
Prodigy 40 points
Part Number: AWR1642BOOST


Hi,

I have observed that when the reflector is placed at around 1.8 meters the 1D-FFT value associated with that bin is around 1.9e4. As the reflector is moved closer, around 40 cms, the 1DFFT value is around 1.05e

An ADC capture was taken of both the above mentioned cases, and the 1DFFT values are plotted on octave. A screenshot of the dump is shown above. There seems to be a decrease in the value of the 1DFFT value as the reflector moves closer.

Why does this happen?. When the reflector is around 1.8 meters the bin is 12(range resolution is around 0.15m) and when the reflector is around 40 cms, range bin is 3..

The profile configuration is as below :

profileCfg 0 77 5 4.3 51.2 0 0 21.53 1 256 5583 0 0 30

Thanks and Regards

Avinash K

  • 0
    TI__Expert 5235 points

    Your HPF settings in the profile are HPF1 = 175 KHz, HPF2 = 350 KHz. You will probably see the attenuation curve corresponding to this combination as seen in the last picture in the thread  

    Your profile slope S = 21.53 MHz/us. IF freq = S * (2*R/c) so per this, for 0.4 m, your IF is 57 KHz, whereas for 1.5 m, this will be 215 KHz, both sort of fall in the HPF attenuation zone but 57 will be much more attenuated than 215.