Zebra Technologies Corporation TFF-1015-0001 Benutzerhandbuch
WhereNet Corp. January 2003
Page 4
Introduction
System overview
The WhereNet Real Time Locating System (RTLS) is designed to permit users to determine the position of tagged assets
in both indoor and outdoor facilities such as factories and freight yards. The system locates tagged assets by a process
involving redundant triangulation. Each tag autonomously emits a 2.4 GHz direct sequence spread spectrum (DSSS) radio
signal at predetermined blink rate. Each tag’s blink rate is randomized around its predetermined value to minimize the
number of collisions between transmissions made by different tags. The signal emitted by the tag is received by a
minimum of four Location Antennas. A typical transmission contains a preamble which is used to synchronize the
receiver, the tag’s serial number which identifies the tag, a status word which monitors various tag functions, data stored
in the tag’s memory and finally a CRC used to assure that the tag’s message is correct as received.
The principal components of WhereNet’s RTLS are shown in Figure 1.
in both indoor and outdoor facilities such as factories and freight yards. The system locates tagged assets by a process
involving redundant triangulation. Each tag autonomously emits a 2.4 GHz direct sequence spread spectrum (DSSS) radio
signal at predetermined blink rate. Each tag’s blink rate is randomized around its predetermined value to minimize the
number of collisions between transmissions made by different tags. The signal emitted by the tag is received by a
minimum of four Location Antennas. A typical transmission contains a preamble which is used to synchronize the
receiver, the tag’s serial number which identifies the tag, a status word which monitors various tag functions, data stored
in the tag’s memory and finally a CRC used to assure that the tag’s message is correct as received.
The principal components of WhereNet’s RTLS are shown in Figure 1.
WhereTag II HO Device
The WhereTag II HO is the same as the existing WhereTag II with the exception that it has a 200 mW RF power amplifier added to
boost the RF ASIC’s power output from 2 mW to 60mW.
boost the RF ASIC’s power output from 2 mW to 60mW.
The WhereTag II HO is the first level component of the WhereNet
Real Time Locating System (RTLS). It is a low-cost wireless device that attaches to a resource (such as an asset, pallet,
container, vehicle, etc.) and periodically broadcasts, via radio, it’s unique identification number. WhereNet’s RTLS
infrastructure detects that signal and precisely locates the tag and it’s associated resource.
Powered by a long-life internal battery, the WhereTag II HO’s beacon signal can be configured to “blink” from every half
second to once an hour. This allows some resources to be tracked second to second while others that are less mobile can
be tracked less frequently. At a typical blink rate of four minutes, the tag’s battery can last six years.
When excited by a WhereNet WherePort, a WhereTag II HO can alter its blink rate (typically faster) to enable more
timely location updates for critical threshold zones such as shipping/receiving docks and other portals.
Each WhereTag II HO has a unique identification number that is transmitted via radio during each blink. When it’s
battery is running low, the tag alerts the WhereNet RTLS infrastructure so that the tag can be proactively replaced.
WhereTag II HOs can be pre-programmed with 12 bytes of supplementary data (such as an asset or serial number) that
can be included with each blink. WhereTag II HOs are configured with WhereNet’s WhereWand.
The number is also printed as a Code 128 bar code on the tag. The bar code enables seamless integration with existing
inventory systems and delivers a cost effective total resource visibility solution that extends beyond the range of the
WhereNet Location Antennas.
container, vehicle, etc.) and periodically broadcasts, via radio, it’s unique identification number. WhereNet’s RTLS
infrastructure detects that signal and precisely locates the tag and it’s associated resource.
Powered by a long-life internal battery, the WhereTag II HO’s beacon signal can be configured to “blink” from every half
second to once an hour. This allows some resources to be tracked second to second while others that are less mobile can
be tracked less frequently. At a typical blink rate of four minutes, the tag’s battery can last six years.
When excited by a WhereNet WherePort, a WhereTag II HO can alter its blink rate (typically faster) to enable more
timely location updates for critical threshold zones such as shipping/receiving docks and other portals.
Each WhereTag II HO has a unique identification number that is transmitted via radio during each blink. When it’s
battery is running low, the tag alerts the WhereNet RTLS infrastructure so that the tag can be proactively replaced.
WhereTag II HOs can be pre-programmed with 12 bytes of supplementary data (such as an asset or serial number) that
can be included with each blink. WhereTag II HOs are configured with WhereNet’s WhereWand.
The number is also printed as a Code 128 bar code on the tag. The bar code enables seamless integration with existing
inventory systems and delivers a cost effective total resource visibility solution that extends beyond the range of the
WhereNet Location Antennas.
WhereTags are extremely durable and can be used both indoors and outdoors. The tag’s case is resistant to oils, solvents
and hydraulic fluids.
and hydraulic fluids.
WhereNet Location Antenna
This device is an active antenna that mounts remotely and is connected to the Location Processor. Its function is to
receive spread spectrum radio signals from the WhereTag II devices. It converts the radio frequency signal to a lower
intermediate frequency and transfers those signals to the reader processor cards in the Location Processor
receive spread spectrum radio signals from the WhereTag II devices. It converts the radio frequency signal to a lower
intermediate frequency and transfers those signals to the reader processor cards in the Location Processor
.