I have followed the quick start videos and set up 4 anchors and set up a network using the Decawave RTLS app and use the “Grid” to view Tag position
Anchor locations are set to 0,0 0,7 7,0 and 7,0 (a 7m rectangle). The Anchors are 2m high and in clear view of each other.
At the moment I have only 1 Tag active
The grid shows 3 of the anchor points ok but for some reason places one of them on the 10m grid line instead of where 7m should be.
The issue is the Tag location keeps disappearing, I cannot get consistent display of its location - making it useless for a real life application with Anchors over 30m apart.
First I tried 100ms updates but the Tag kept showing up then disappearing. I then set update for both movement and stationery to 500ms but still keep loosing the Tag for 9 or 10 seconds at least , several times a second.
Have you used the autopositionning feature ? If yes it may explain why one of the anchor position is inaccurate, we have seen such result in the past with one anchor being offset. It sounds like you know the exact position of your anchor so I would recommend to set the coordinates manually.
The reason you see only 3 anchors on the app may be due to the limited number of ble connection. But I would still expect you to see 4 greys ones.
The tag disappearing means that the location engine is not always able to calculate a position. I would recommend to verify the accuracy of your anchor coordinates, as if they are not accurate, there may be no existing solution for the trilateration algorithm (algorithm that calculate the position).
If you want to do further debugging, I would recommend to setup a serial connection to the tag through the USB port. Then we have some shell mode commands such as “les” or “la” which will help you to understand what is wrong with your setup.
Please have a look at the document below section 4.3.1.1, it details how to setup the serial connection.
I rechecked the settings and had entered incorrect coordinate for 1 anchor, now the 4 anchors are in correct position.
I also let the app update firmware and notice now there are “rubber bands” connected to first Tag.
The system seems to work now but I have a dead spot where the Tags disappear. This is where the Tag is not in good line of sight to the Initiator Tag but is is still in good clear line of sight with the remaining 3 anchors. If the Tag shows correct location then doesn’t this mean the anchors are hearing the initiator in order to synch with it? That being the case, why would there be a dead spot in the room?
Note: the area is only 7m x 7m approx. Anchors are just over 2m in the air.
I also assume if I tag into the serial port on the Tag and use this to determine the position that I will not see lag that I suspect is introduced by bluetooth link to android?
Ok, good progress. It is very important to have accurate anchor coordinates in order to get a performing localization algorithm.
Regarding the “dead point”, you should check the UART output in this area. You may think that you have LOS with 3 anchors but if by any chance the tag actually ranges to only two anchors, then there will be no position calculated and it the tag will effectively disappear from the android app viewer.
You are right in your assumption. If the tag reports good position on the uart but actually keep disappearing from the android app then there is an issue with the BLE link. But the most likely issue is that the tag does not calculate the position so double check the uart.