Anchors disposal in a large area

I´m planning to use the MDEK-1000 in a large plain area in a proof of concept. Anchors will be on a tripod 2.1 mether height. There will be 24 anchors and few tags.

My point is:

  1. What is a reasonable distance between two anchors in LOS ? 30 meters ? Could it be bigger? I saw some recommendations here of 30 - 60 meters maximum.

  2. Do the anchors need to have the same height ? If not, is there a specific rule to apply ?

  3. Instead of having anchors forming a square, can I have a straight line of anchors separated by a distance of 30 meters like the picture bellow ? If D is 15 meters, C shall be 33.54 meters which is the maximum to be in range with at least 3 anchorsanchors in line.pdf (23.1 KB) Will this work ?

  1. It depends on your environment…any obstacles? metal objects around? etc.
    I personally did not try 30 meters due to lack of space…

  2. If you are not interested in accuracy along Z axis (vertical) then anchors can be at the same height.
    I experimented a lot with Z-axes and followed the advice I got on this forum placing anchors at as much different heights as possible (ceiling height restricts and there is no much you can do about it) in order to get reasonable accuracy of 10-15 cm.

  3. Anchors do not have to form a square, but I have not heard here about Anchor configuration forming a straight line and did not try it - my got feeling says it won’t work well… Just be aware that the closer Tags located to the perimeter of the Anchors’ rectangle/polygon the worse accuracy you get. That means the close your Tag will get to the ‘line’ the worse the accuracy you get.

Hi @nudel

We tried to setup a RTLS system, following the instructions of Gateway Quick Deployment Guide, in a 30x7 meters room, as shown in the figure below. We used 6 anchors (1 as an initiator), and 1 gateway.

We needed to position the gateway in the center to the system identify the 6 anchors. But due the columns with core made by steel, the anchors marked as red had a poor performance. When the tags were close to the red anchors, we didn’t get a correct location.

The next test we’ll do is use two and three gateways, and verify we get a better accuracy.


Physics has its own limits. High frequency operation in a metal environment has issues that direct path is highly attenuated.

I believe that one way to fix it is to put two more anchors , one in the middle of two columns aligned with initiator and anchor and another anchor between the two other anchors in such a way that at least 3 anchors can see each other.

Maybe you can try this instead of using 2 other gateways

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Thanks for suggestion @nudel.

Ok progamonauta. As soon as you change, please let us know here.


@nudel pointed it out rightly. The issue here could be solved by having more anchors near the red ones. Having good geometery of the anchors is also important to achieve good position estimation (look for GDOP).

@nudel regarding your questions:

  1. as @securigy2 has mentioned, it depends on environment. You need to keep the nodes out of fresnel zones and pointing the antennas in favorable direction to achieve 30+ meters. For a robust installation I would say 18-23m should work fine.
  2. see GDOP, the geometery is important to achieve good position estimation. A line can work but it will jump. Don’t expect sub 20cm accuracy.