TREK1000 User Manual
© Decawave 2016
This document is confidential and contains information which is proprietary to
Decawave Limited. No reproduction is permitted without prior express written permission of the
author
Page
44 of 54
Figure 46: Trilateration
– 2 Solutions Exist
For systems that only measure x and y, or systems that mount the Anchors above the Tag,
this is sufficient.
8.2.1 Adding a 4
th
Anchor (example only)
A 4
th
Anchor is
not
required if:
1. the Tag is always below the plane of the 3 Anchors, or
2. the system only requires x-y co-ordinates (2D) and the z-height is not required (3D)
A 4
th
Anchor would be required to resolve the 2 solutions if the Tag can be located above or
below the plane of the Anchors.
If a 4
th
Anchor is added, TREK1000 uses data from that anchor to select the correct solution
from the 2 returned solutions.
Method:
Add the 4
th
Anchor on a different plane than the first 3 anchors. It is recommended to mount
it above the other 3 Anchors to give better line-of-sight to the Tag (less obstructions from
people, furniture etc.)
Figure 47: Adding a 4
th
Anchor
For best performance, the difference in height between 4th Anchor and the plane of the
others should be as large as possible.
The solution selected is the minimum of ABS(R
– D1) and ABS(R – D2), where D1, D2 are
