Anchor Synchronous Transmission for TDOA

Hi all.
We are approaching the UWB world. Our challenge is to make a system with big coverage, and high number of tags. We need to know the position at the tag. In fact we want to do a GPS-like positioning system indoor. We studied several solution in App Notes but I think that the best solution for us is to synchronize anchor with scheduled transmission. The TDoA will be made by the tag. This kind of operation is very similar to GPS. I would like to know if this solution has been already considered and if there is some documentation useful for start developing this architecture.
Thank you.

Hi Zanone,

In a classical TDOA scheme, the anchors have their clock synchronized and receive a blink message from the tag with a slight delay. Based on that, a master anchor can calculate the position of the tag. Such a system offers very large tag density and low power, supporting large number of anchors too.

In the scheme you are suggesting, the tag will have to be in receiver very often. It will be difficult to develop a low power application in this case. Similarly, your system may work for a limited number of anchors but I’m not sure it is scalable.

I haven’ t seen such TDOA architecture so far, but I guess you could do some proof of concept to see feasibility.


Hi Yves.
Yes the power consumption of the tag will be high if we want to know the position in real time but in most cases this could be not a problem. For battery operated asset tracking application maybe we can relax the position measurement period. You stated that you are not sure about the scalability of such system. You are right, this is a critical aspect. In fact my idea to create groups of 16 anchors with 16 time slots. for larger number of anchors we can repeat the slotting scheme This number of anchors is for having a reasonable distance between anchors with the same slot Do you think that the calculation of the TDoA will be critica with this high number of slot?
Even if using a very stable TCXO?
Thank you.