Max Distance Ranging

All discussions related to the Loco Positioning system
jdiep
Beginner
Posts: 9
Joined: Mon Feb 25, 2019 2:03 pm

Re: Max Distance Ranging

Post by jdiep » Mon Jul 22, 2019 12:33 pm

Thanks, let me check if the distance to the ground makes a difference.

Btw, is it also normal that the ranging offset changes according to where the tag is placed?

In my lab, I have access to a Vicon system in order to measure the actual distance.

1. If I attach the tag on the drone, and I place the anchor at a distance of 2m, I measure roughly 1.9m with LPS with a 0.1m offset.
2. However, if I place the tag on a cardboard box (as can be seen in one of the above images), I measure an offset of 0.5m.
3. If I change the immediate environment a little bit (for example moving the chair in the above image, while guaranteeing LOS condition), I realize that the range measurement fluctuate by roughly 0.3m.

Is this behaviour normal and how can I mitigate the variance?

(Sorry, I asked this question in a previous thread before, but didnt receive any answers).



kristoffer
Bitcraze
Posts: 107
Joined: Tue Jun 30, 2015 7:47 am

Re: Max Distance Ranging

Post by kristoffer » Wed Aug 07, 2019 8:08 am

1. If I attach the tag on the drone, and I place the anchor at a distance of 2m, I measure roughly 1.9m with LPS with a 0.1m offset.
There is usually some offset, I also think there is some non linearity involved for short distances, probably in the 0.1 m range.
2. However, if I place the tag on a cardboard box (as can be seen in one of the above images), I measure an offset of 0.5m.
3. If I change the immediate environment a little bit (for example moving the chair in the above image, while guaranteeing LOS condition), I realize that the range measurement fluctuate by roughly 0.3m.
Can it be that the module picks up a reflection that traveled a longer path? If you have LOS I would expect it to trigger on the main path though.

I think it is possible to get information in the DWM1000 module about the signal quality as well as multipath properties but we have not explored that. Maybe that is a way forward?

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