User's Manual

©WhereNet Corp June 2001 TFF-1015-000-4589_UserMan_rev_08_30_05 Page 5
Integration of these standard APs allows complete compatibility with wireless LAN infrastructure. All the
wireless services required within an enterprise are then available on a single infrastructure.
WherePorts
The WherePort transmits a short range, adjustable from 5 to 20 feet, 127 kHz electro-magnetic signal. This signal
defines a field. The field may indicate an entry gate or transition point. Each WherePort is programmed with its
own ID. When a tag receive a WherePort trigger it transmits the WherePort ID along with its own ID to the
location server. The server then knows that the tagged object has entered the gate or completed a transition.
Because the location of the WherePorts is known, the server can locate the tag according to the
WherePort field even if the tag can not be located on the full X-Y coordinate grid of the location sensors.
Communication
The WhereTag has multiple types of transmissions, keep alive blinks, switch blinks, and WherePort/data blinks.
The keep alive blink is controlled by the WhereTag and blinks at the programmed interval. Switch blinks and
WherePort/data blinks are triggered by activity on a switch, a WherePort field, or a telemetry request from the
host.
There are three formats for messages, short, medium, and long. The shortest one identifies the WhereTag
and is used for location processing. The longest transmission can include 88 bits of telemetry information. When
connected to a host microprocessor, additional information about the tagged item and its status can be transmitted.
The WhereNet system is scalable. A single Location Sensor and server can detect the presence of a
WhereTag within its 1,000 meter outdoor range. In addition, it can receive telemetry data, such as vehicle VINs,
fuel status, and mileage from WhereTag equipped vehicles. Or hundreds of Location Sensors can be
interconnected to cover a site of hundreds of acres and provide accurate X-Y coordinates for tracked assets on a
map of the site.