User guide

Hub administration
D2119 Dart RTLS User Guide 71
By default, this receiver pruning based location algorithm is disabled. The user can enable it
using Hub Administration and Management application. After the pruning algorithm enabled,
whenever Dart RTLS system fails to produce a good tag location from a tag blink in the standard
fashion, it starts analyzing and pruning received timings and will most likely output a valid tag
location.
Pruning Criteria: The following criteria are used to judge whether the location computation is
good or bad.
1. Bounding Box – If locate computed is outside the bounding box of the virtual group,
then it’s a bad locate. This criterion is used as the default.
2. DQI (Data Quality Indicator) – If DQI filter is enabled, then the DQI threshold is used to
determine if a locate is good or bad. In theory, DQI value of 2.0 or under indicates good
accuracy in position measurement.
3. GDOP (Geometric dilution of precision) – If GDOP filter is enabled, then the GDOP
threshold is used to determine if a locate is good or bad. In theory, GDOP threshold
between 1.0 and 2.0 is a good setting for well-designed deployment.
Algorithm pruning limit: Dart RTLS system enforces a limit on how many received timing can
be pruned. Limit varies on size of detecting receiver set and virtual group configuration. If
minimum number of unit in a virtual group(VG) is – M, number of receivers receiving the tag
blink in this VG is - N, stop pruning if valid location is obtained or when K receivers left , where
K = MAX(M, N* 3/4).
K is calculated as an integer, floating value will be truncated.
Example: For a VG with 9 receivers detecting a tag blink, if min units is set to 3,
M = 3, N= 9, so K = MAX(3, 9*3/4) = MAX(3, 6.75) = MAX(3, 6) = 6 . So pruning may continue