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ChapTer 7 - Wireless loCaTion
» overview
In AlphaECall™ 200 when a wireless location is setup, AlphaECall™ 200 can determine the approximate location of wireless input
device types that are not in a fixed location (ie. necklace or wristband pendants). This can provide emergency responders with critical
information needed to quickly find someone in need of assistance. Location is established by using an algorithm applied to signal
strength from the alarming pendant.
A wireless network coordinator and wireless repeaters mounted in fixed locations will receive signals from an alarming pendant at
different signal strengths. Using those signal strengths AlphaECall™ 200 can triangulate where a pendant is located when it is acti-
vated.
In the Wireless Map area you will be able to teach AlphaECall™ 200 the layout of your facility by sending wireless signals from
numerous location throughout the facility. The signal strength from each location in your wireless map will be recorded in a data-
base and when an actual emergency call comes in from a pendant, the signal will be compared with the data in your wireless map to
determine the approximate location of that pendant. This process is called "Finger Printing".
» repeater location
The wireless repeaters (WRL511) provide the backbone of the location functionality used in the AlphaECall™ 200 Series system. It
is at the repeaters where signal strength information from an alarming pendant is measured and compared to your wireless map
to determine the location of a pendant. As such, repeaters must be configured with more care in a location finding facility than in a
facility where repeaters are used solely for increased transmission coverage.
When mounting repeaters it is important to place them so they are at different distances from locatable areas in your facility. AlphaE-
Call™ 200 may have difficulty discerning between two alarming pendants that are roughly the same distance from a repeater. A
pendant activated 100 feet to the west of a repeater will appear exactly the same as a pendant activated 100 feet to the east.
For instance, the repeater shown in Figure RL-1 would have a difficult time differentiating between the two pints. The signal provided
by both will be similar, as they are both of a roughly equal distance from the repeater and the obstacles between each repeater are
almost the same.
The repeater shown in Figure RL-2, however has been installed such that there is enough difference in the obstacles and distance
between the two points that differentiating between the signals should be easier.
Repeaters used for location should be mounted from immediate obstacles, large metal objects, and as high as possible so they can
receive call transmission data easily.
One simple way to create configurations that promote good signal quality is to arrange the repeaters in triangle patterns, such as in
Figure RL-3.
If mounting repeaters in a building with more than one floor, use offset triangles from floor to floor as shown in Figure RL-4. Stacking
repeaters vertically from floor to floor will not create the signal diversity necessary to establish location.
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