Hello everybody,
I’d like to install the system in a rectangular room of 5m x 17 m. Actually in my installation I have 6 anchors: 2 mounted on the short sides (one per side) and 4 in the biggest ones (2 anchors per side).
So in my installation I have 2 couples of anchors face to face (180 degree orientation - anchors 1-2-4-5 in the image) and the other 2 perpendicular to the previous ones (anchors 0, the initiator, and 3).
I take care to always have the counterclockwise orientation in the anchors power up.
I have a lot of noise in the position measurements I receive, so my question is:
is it possible that the anchors should be installed at different orientation?
Also because in order to reduce the noise and increase the precision I had to move from 4 to 6 anchors, and in my opinion 6 anchors are too much for a such small environment.
Generally I would say you should aim to have the flat of the antenna facing into the room.
i.e. using the image on page 15 of the datasheet here https://www.decawave.com/dwm1001/datasheet/ the x axis should be parallel to the wall with the Z axis pointing into the room.
If possible the unit should be a little bit away from the wall. All electronics should be below the antenna and towards the wall if possible.
The tag should be in a similar orientation, i.e. y axis pointing up with all electronics below and as far away as is practical.
Going by the antenna plots in the data sheet this orientation doesn’t give the most uniform gain possible however it avoids any risk of polarization mismatched. It also allows the tag to get an equally good view of all anchors without the supporting electronics blocking the signals.
I have found in the past that with PCB antennas while the gain pattern in the plane of the antenna (e.g. directly along the x axis) may appear good the delay characteristics aren’t uniform and so you can get rapid changes in the measured range for very small angle changes. By pointing this axis along the wall (and so away from where the tag will be) you get more uniform range measurement. You still get this issue with the tag antenna but there isn’t a lot you can do to avoid that short of changing the antenna.
Other things to look when trying to get more accurate results are ensuring a good line of sight at all time, accurate anchor location data and having a slight variation in locations (avoid having all the anchors on the same plane, vary the heights and don’t put several in a perfectly straight line).
