Decawave net deployment: Some question about it

Hi everyone
I want to share with you a deployment in a warehouse for a tracking solution (No gateway installed because communications are via wifi). I show you some reference measures in order to understand the distances (All in meters):

See in the attached document: Picture 1: Anchors distribution

There are 16 anchors (A020 to A036), two of them are initiators (A021 and A031, both with green dots). I clarify some relevant information:

  • The yellow triangles indicate the direction in which the anchors mainly point (that’s important due to LOS because for example, A027 and A028 are mounted in columns).
  • The average Z level is 7 meters in average in all anchors.
  • Assume LOS between anchors

What we expect (But doesn’t occur):

  • Having less than 30 anchors, I assume that I will have 16 different seat numbers, one for each anchor (one of the initiator will take a non zero seat number).
  • After the initialization process, all anchors should get a different seat number and should remain with that number (until a major change in the network occur).
    What we actually see (Using DRTLS V14 (1405), firmware 1.3.0 build time 03/29/2019 13:43:44):
  • We have one initiator (seat 0), but different anchors have the same seat number (e.g I can see 3 anchors with seat number 4, 4 anchors with seat number 6, etc) and the seat number seams to be constantly changing on the anchors (this happens in most of them).
  • In one opportunity, an ordinary anchor took the seat number 0 (supposedly only for the initiator) and to be honest that was pretty unexpected. After a few minutes, that same anchor took a different seat number.

My Conclusion: I understand that this is due to a bad synchronization between anchors and this lead to a bad coverage in the area. As shown below, there are breaks in the paths. I think that is a non position resolution (a tag see less than 3 anchors). Also there are some position resolutions outside the wharehouse (not possible). The X Y Z coordinates are ok.

See in the attached document: Picture 2: Path breaks

My questions:
Could these path breaks be related with the issues mentioned above? Or is a lack of anchors installed in the warehouse? Any clue of why I get repeated seat numbers? Thanks in advance.
Juan Pablo

Hi Jaun,

Any clue of why I get repeated seat numbers

Because you have 2 initiators. By having 2 initiators, you essentially have 2 networks. Likely they are competing for the same PAN-ID. Instead you should use only one initiator, not all anchors need to be in range of the initiator thanks to “clock levels”

Have a look at the DWM1001 / PANS system overview, specifically section 5.1 System Expansion - Anchors.

Hi Seppe, thanks for your reply. I forgot to write that one scenario was using only one initiator. Same result. I will read the link you gave me