Source of asymmetric TOF formula?


the DW1000 user manual specifies both a symmetric TOF formula and an asymmetric TOF formula.




The symmetric one is obvious.
There is no explanation for the asymmetric formula though (I also checked APS013).

Can anyone explain what method this formula is based on/why it works?


See the EVK ARM source code attachéd. eg chapter 6. 6 RANGING ALGORITHM.
But could I ask what revision of APS013 you have? Version 2.0 (and higher) is all about asymmetric TWR

Both are attached

Hello Leo,

thank you for replying. The documents did not answer my question though: What is the idea behind the asymmetric formula?

I am not asking about the ranging protocol - I am only asking about the formula.
I understand that the formula is displayed on page 19 of the EVK ARM source code guide and on page 4 of APS013.

But the only explanation is:
“Figure 11 shows this exchange and gives the formula used in the calculation of the range”

Where does the formula come from? Why does it work? Is there any literature?


PS: I am using version 2.2 of APS13, which is the same as your version 2.3 besides the new logo/layout.

Hi Lukas,

The formula is described in the appendix D of the IEEE Standard document 802.15.8-2017 which I think is widely available.

But please find appendix D, The maths of two way ranging attached.


Hello Leo,

thank you very much for the fast reply. This was exactly what I was looking for.

Best regards