User guide

Configuring Dart RTLS
D2119 Dart RTLS User Guide 39
Z space to track must be surrounded by receivers and the X-Y-Z distances need to be
relatively equivalent. In most installations, it is not practical to install receivers in
positions where the X-Y-Z criteria yield accurate results.
1D and 2D—Select if you want the system to perform 2-D calculations when three or
more RTLS Receivers detect the tag transmission; alternatively, it provides 1D position
data when two RTLS Receivers detect the tag transmission.
2D and 3D—Select if you want the system to perform 3-D calculations when four or
more RTLS Receivers detect the tag transmission; alternatively, it provides 2-D position
data whenever three RTLS Receivers detect the tag transmission.
 Minimum Units: Select the minimum number of RTLS Receivers that must detect a
specific tag transmission for location computation. Sometimes, requiring more Receivers
within a given Virtual Group to have received a tag transmission before computing the
tag position can enhance accuracy. If Compute Type is set to 1D, 1D/2D, or 2D/3D, this
field is unavailable for editing.
The following list specifies the minimum number of Receivers required per Compute
Type:
 1D and 2D data: 2
 2D and 3D data: 3
 1D data only: 2 (minimum and maximum)
 2D data only: 3 or more
 3D data only: 4 or more
 Priority: Select the priority of this Virtual Group for arbitrating between tag data
positions that are calculated by two or more Virtual Groups. The group with the highest
priority for a given successful data computation generates output. When a tag
transmission is received in more than one Virtual Group, the hub software will generate,
in addition to a location result for each group, an estimate of the time of that
transmission. Rather than output a location result for each VG with the same priority, the
hub software will compare the time estimates and only select for output the result from
the VG with the earliest transmission time. Since this result is based on data from the
most direct signal path, it is the best estimate of location. This selection is only possible
when the various VGs are properly connected with overlapping and functioning
reference groups.
For example:
Example 1—Groups having unique priorities. This causes the highest priority group
(lowest numerical value) with a successful data computation to output position data.
Example 2—All groups set with equal priority. This causes all successful data
computations from all enabled virtual groups are under further arbitration to generate