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IWR6843: Derive RCS value from demo visualiser output

Dinesh S1
Prodigy 220 points
Part Number: IWR6843


Hello Team,

I would like to derive the Radar Cross Section of my target using the existing demo visualiser output parameters. As I understand from your document that, RCS is a measure of the amount of energy the object reflects back.

Is there a straightforward way to get the RCS of my target? Kindly, suggest any other tools also if available.

Thanks

Dinesh

  • 0
    TI__Mastermind 40905 points

    Hi, Dinesh:

    I have to say, it is not easy.   You have to know the exact transmit power, transmit/receive antenna gain, the exact distance, the exact noise figure on the receive path, and then the target has to be a point target. 

    Below is the information on the relationship with SNR and RCS.  But if you know SNR, then the RCS can be derived.  Note that when you calculate SNR, please use peak power on zero Doppler to get the signal power for the point target.  and then average non-zero Doppler signal power to get noise estimation. 

    Maybe you can give a try with the corner reflector with known RCS to see how accurate you can be.   

    SNR and RCS relationship:

    •SNR of the ADC sample is related to the transmit power, propagation loss, RCS of the target and thermal noise level in the received chain and the ADC sampling rate.
    •After 1D FFT, there will be processing gain from range FFT.
    •After 2D FFT, there will be processing gain from Doppler FFT
    •At the end, the SNR of the whole system can be listed as

    SNR=((RCS ×(P_t * G_tx * G_rx λ^2)/((4π)^3*R^4 ))×T_s)/(0.9k_B T_0 N_F )×N_adc×N_(chirp_loops)

    Where Pt is the transmit power; Gtx is the transmit antenna gain; Grx is the receive antenna gain; λ is wavelength; R is the target distance; the KB is the Boltzmann constant equal to 1.38x10-23 J/K, T0 is the absolute ambient temperature in K; NF is the noise figure; Ts the ADC sample duration, Nadc is the number of ADC samples per chirp. Nchirp_loops is the number of chirp per frame; Nant is the total number of visual antennas.

    •In the above calculation, only the thermal noise is considered for SNR calculation, so please use the max RX gain so that the thermal noise will be dominant (compare to ADC quantization noise).
    Best,
    Zigang