AWR1443: How is the maximum range calculated in mmWave Sensing Estimator tool?

Faiz Ahmed

Intellectual 460 points

Part Number: AWR1443

Hello,

I was curious as to how mmWave Sensing Estimator is calculating the maximum range?

I am entering the following parameters in mmWave:

To keep it simple, I am using 1 TX and 1 RX antenna with 0 losses.

I realize that maximum distance is dependent on the radar range equation and the slope/IFfreq equations:

Using the 2nd equation, I can get the desired range of 70 with the chirp parameters: S = 7.21MHz/us and Fif = 3.36MHz.

What I don't understand is how the "Max Range for Typical Detectable object" of 84.61m is calculated?

I am using the radar range equation with:

RCS = 5

Pt = 12 dBm =0.0158W

Gtx = Grx = 9 db = 7.94

wavelength = 3.95mm

Tmeas = number of chirps * Chirp duration = 65 * 55us

SNRmin = 12 dB = 15.85

Temp = 293K

F = 16 dB = 39.81

Bandwidth = 5MHz

This only results in 1.5m which is of course not correct.

1) I am curious as to how Tmeas is calculated? Isn't it just number of chirps x chirp time?

2) How is the bandwidth calculated? Would it just be the IF bandwidth?

Thank you,

Faiz

over 8 years ago

0 Vivek Dham over 8 years ago

TI__Guru 58035 points

Hello Faiz,
As you pointed out the max range is either limited by the SNR (equation 1) OR by the IF bandwidth (equation 2 you have mentioned). the sensing estimator is only using the SNR as the limitation factor. In the first equation you have put the bandwidth (B) is not involved. I can see that as one possible mistake.

You are right the Tmeas is number of chirps * chirp time.

Regards,
Vivek

0 Faiz Ahmed over 8 years ago in reply to Vivek Dham

Intellectual 460 points

Hi Vivek,

Thanks for pointing that out. You are correct.

Why is the bandwidth not considered? Wouldn't the noise floor increase as bandwidth increases which would decrease the SNR?

Thank you,

Faiz

0 Vivek Dham over 8 years ago in reply to Faiz Ahmed

TI__Guru 58035 points

Hello Faiz,
There are multiple algorithms that can be used for object detection which could look at at noise differently and hence have different definitions of detection SNR. But typically in a CFAR detection the "noise" level is looked at a few bin around the object bins. So the whole bandwidth need not be accounted but the noise levels only in the bins used for noise level measurement. So what is important is SNR used for detection and that accounted for what ever defination used, this is already included in your equation.

regards,
Vivek

0 Vivek Dham over 8 years ago in reply to Vivek Dham

TI__Guru 58035 points

Hello Faiz,
Did this help clarify your doubt?

Regards,
Vivek

0 Faiz Ahmed over 8 years ago in reply to Vivek Dham

Intellectual 460 points

Yes, thank you.

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AWR1443: How is the maximum range calculated in mmWave Sensing Estimator tool?