bt6.0 channel sound distance calculation

[qingsong]

i use two development boart, one download "channel_sounding_ras_initiator" example, the other download "channel_sounding_ras_reflector"  use two board to test distance, the board will print

below is test value,How can I calculate the actual value based on the printed value?

Test scenario	ifft	phase_slope	rtt
0.5m	1.01744462	1.37687158	7.55163826
1m	1.53813306	2.75733968	8.51521366
2m	2.85108002	5.48934368	9.88555026
5m	8.4262566	13.8329916	20.44672402
10m	14.26080746	20.22967842	24.01617924
30m	22.500557	29.009472	35.065941

[witc]

Here I guess each must find their own way to combine these values. Kalman filter, weighted average, median...?

[qingsong]

are you some suggest?

[qingsong]

Does the product need to be calibrated before leaving the factory?

[Elfving]

Hi,

qingsong said:

Does the product need to be calibrated before leaving the factory?

Not necessarily, you might want to calibrate the clock and write to the UICR or something though.

Regarding the rest, it is true what witc says below here. 

The printed value you get the there are acctually 3 attempts at getting the real value; the numbers there are guesses at the range, in meters. First of all, we need to keep in mind that CS isn't UWB; the best you can expect is ±0.5m. Differentiating between ±0.5m would be impossible/hard. But you can differentiate better than what the sample is currently doing - the sample is more of a demo of the underlying technology, giving you the ingredients to make something out of yourself.

Secondly, it is tempting to simply say that you should disregard anything but the IFFT measurement - which I would also claim performs ok-ish in the tests you've shown. However, the truth is rather that all of these metrics work best in different situations. RSSI is okay in short range for instance, and RTT is best for very long ranges. This old webinar (which is meant to describe how our old "Distance Toolbox" worked, but the tech is almost the same) goes a bit further into the details of what separates these measurements. Another thing I just realized when finding the webinar now is that phase slope might get you a max range, but don't quote me on that.

Most importantly: if you really want a good accuracy for your product, what you would typically do is to buy a third party algorithm that gets you a better accuracy than what our free code does. I assume the better algorithms combine all of these metrics in some fancy way. If you contact your local regional sales manager I bet he would be able to put you in contact with someone selling third party CS

Regards,

Elfving