IWR6843AOP: About the accuracy in the level_sensing lab

Tony Simple

Part Number: IWR6843AOP

Hi expert,

We are working on a project in which the range bias has to be controlled with in ±2mm when detecting a large target in 2~40m.

And the level sensing lab seems to be a good start point. Would you guys help in the following questions:

1. How to calculate the resolution for the zoom-fft used in the level sensing project?
2. Is AoP capable of detecting a large object in 40m?

Thanks

Tony

over 3 years ago

+1 Brennan Hartigan over 3 years ago

TI__Genius 10634 points

Hi Tony,

Here are some statistics about the device capabilities in this lab:
1. Your FFT resolution at 2-40m would be 512x512. Please let me know if this was not what you meant by "FFT resolution"
AoP is capable of detecting a large object at 40m

Regards,

Brennan

0 Tony Simple over 3 years ago in reply to Brennan Hartigan

Intellectual 390 points

Hi Brennan,

Thanks for your quick response and the accuracy is exactly what I need. But I am still interested in how it is calculated.

I understand how the range resolution is calculated which is basically depending the bandwidth we use. But how the range accuracy is calculated in your table? Would you please give some hints on that? Formulas would be really appreciated.

+1 Brennan Hartigan over 3 years ago in reply to Tony Simple

TI__Genius 10634 points

Tony,

In general, range accuracy is calculated as follows:

Range Accuracy = Range Resolution / Sqrt (2 x SNR).

However, the achievable accuracy also depends upon (limited by) the size of the FFT as it defines the FFT resolution (aka range inter-bin resolution). Intuitively, the FFT granularity needs to be fine enough to measure the desired range increment and so the application may need to first get an initial coarse range measurement using the provided chirp configuration and then perform a zoom FFT on the range of interest, using additional processing in software with a higher order FFT.

I will link a few existing E2E threads with more information on this for you to look at:

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/707391/range-velocity-angle-accuracy/2607546#2607546

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/618907/iwr1443boost-sub-millimeter-accuracy-distance-measurement-on-a-short-range-from-5-to-30cm

Regards,

Brennan

0 Tony Simple over 3 years ago in reply to Brennan Hartigan

Intellectual 390 points

Thanks for your detailed and intuitive answer.

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IWR6843AOP: About the accuracy in the level_sensing lab