User Manual

30 System Installation PLUS System Manual
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2.4.7 Reader Groups
2.4.7.1 Reader Groups Overview
The ability to create Reader Groups is an important feature of the 2.0 Location Engine. Establishing
multiple Reader Groups allows a large installation to be divided into small sections, each of which
acts as an independent location system. Managing a PLUS system as a set of small, independent
systems is much easier than trying to work with one large group of Readers. By creating independent
groups of Readers, the user can install Readers that operate off of different SDPs, are located on
different floors of a building, or are located in geographically separated areas.
2.4.7.2 Solution Types
When a group of Readers is created, you can set properties that control the type of location solution
that the group can produce. Groups may generate 0D, 1D, and 2D solutions.
0D Solutions, also called presence detect or proximity solutions, determine which Reader is closest to
the Tag and report the X,Y coordinates of this Reader as the Tag location. This type of solution is
useful when the general area of the Tag is needed. Reliable 0D solutions can be produced with a
sparse density of Readers.
1D Solutions are produced by assuming that the Tag solution will lie on a line between two Readers.
1D Reader groups are generally created with Readers in a hallway, when the tag is unlikely to enter or
be detected in rooms alongside the hallway. When setting up 1D groups, the participating Readers
should be at approximately the same height.
2D Solutions can be calculated when at least three Readers with good geometry are able to receive a
Tag. The X, Y, and Z coordinate of the Tag are reported, where the height (Z coordinate) is an input
to the system. When setting up 2D groups, the participating Readers may be at varying heights.
2.4.7.3 Tracking Cells
A tracking cell is a geometric region that acts as a filter for Tag locations. One tracking cell can be
defined for each Reader group and each map. You are not required to define tracking cells – if no cell
is defined, all valid outputs of the Location Engine will be used. Tag solutions that are inside the
tracking cell are considered valid. Tag solutions outside the tracking cell are either discarded, or are
snapped to the boundary of the tracking cell, depending on the parameters that the user has set.
Readers may be located inside or outside the boundaries of tracking cells – the cell operates based on
Tag positions, not the Readers used to generate those positions.