Accessing distances from more than 4 anchors

dwm1001
mdek
#1

Hi!
We are attempting to use the MDEK1001 in our own localization algorithm. For this, it would be very useful to be able to access the distance measurements from all the anchors, not only the 4 closest ones.

In the DWI Firmware API guide, it seems like the dwm_loc_get message could return the range to up to 16 anchors if the message is also sent by an anchor. But in my tests this always returned 0 distance encoded values (here all nodes were set up as anchors in one network).

Alternativly is it possible to affect which 4 anchors a tag will return the distance to? If it is possible to cycle through all the anchors then that could be an ok solution.

Lastly, to do auto positoning of all the anchors with our own algorithm we would need the distance measure from all anchors to all anchors. Is it possible to access this information without physically connecting to all the anchors? Which options do we have for accessing this info?

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#2

Hi Sverre,

This is not possible using PANS. A tag will only range to 4 anchors maximum per TWR slots, and there is no possibility to select which anchor the tag will range to. Anchors are automatically selected.

The ranging scheme was explain in details in other threads I think so maybe take a look on the forum.

In theory, if you run the auto-positioning routing after deploying all your anchors, anchors should range to each other.

To retrieve this data without physically connecting to the device, you can develop a user application that will allow to send the position to the cloud through uplink data. Maybe take a look at the firmware user guide and gateway quick deployment guide.

Thanks
Yves

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#3

Hi Sverre,

another option would be to read out the distances on each of the Anchor using Bluetooth interface. The DRTLS Android Manager only do it with the in-range anchors, but each anchor should contain measurement data to its in-range anchors once the auto-positioning was trigger on the Initiator.

You can easily test it with e.g. nRF Connect or by modifying the DRTLS Android Manager codes.

Cheers,
TDK

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