User's Manual

Tags User Manual PRF-TAG’s
Page 5 of 15
The following describes the signal flow of a PureRF system:
A PureRF receivers are deployed throughout the monitored space in order to pick up the
RF signals that are transmitted by PureRF tags that are installed on monitored assets (for
example, in the drawing above, a person and a copy machine). The size of the monitored
space can vary from a single door to an entire campus covering wide areas both indoors
and outdoors. In the drawing above, the blue area designates the combined coverage of
the four installed receivers. The receiver that picks up a PureRF tag indicates the tag’s
location because a PureRF tag must be in the vicinity of a receiver in order for the
receiver to pick up its signal.
When covering a wide area, the receivers may overlap and therefore, several receivers
may receive the same signal. In this case, the location of the tag is determined by the
receiver that receives the highest signal strength (highest RSSI). The receiver that picks
up the transmission adds its own unique ID to the tag's message that represents this
tag’s (asset's) current location. Additionally, the receiver can perform conversions
between various commonly used interfaces/protocols. More information is provided in the
What is a PureRF Receiver? section on page 7.
B PureRF activators are used for improving the accuracy of locating assets compared to
what is provided by the receiver ID. For this purpose, PureRF activators are deployed
throughout the monitored space wherever improved tag location measurement is
required. The PureRF activators continually transmit a short-range uniquely identifying
Low Frequency (LF) signal. Tags can read this signal when they are close to the activator
(up to about 2 meters/6 feet). In the drawing above the pink area designates the
activators’ range. The activator ID that a tag reads is added to the message that the tag
transmits to the receiver. An activator’s ID indicates the location of a PureRF tag at that
time because the tag must be physically close to this activator in order pick up its signal.
More information is provided in the What is a PureRF Activator? section on page 8.
C PureRF RFID tags repeatedly (in a random timing to reduce interferences) transmit their
unique ID and their status (Low Battery, Motion or Tamper/Panic). Whenever a tag is
close enough to a PureRF activator to pick up its signal, the PureRF RFID tag adds the
received activator's ID to its periodically transmitted message. These transmissions are
picked up by the nearby receivers. More information is provided in the What is a PureRF
Tag? section on page 6.
D The application that manages and controls the assets/personnel runs on a standard PC.
This application can communicate with the connected receivers through the PureRF API
(SDK) via the following interfaces/protocols: RS232, RS485, Wiegand, Ethernet and Wi-
Fi. The application periodically collects the tags status messages that the receivers
collect and records them in its database. Each tag message received contains the unique
ID of the receiver that picked up its signal. The application can also analyze the database
periodically to generate additional events based on status combinations.