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Active radio frequency identification (RFID) tags are now commonly being used to track and locate valuable assets in the healthcare, manufacturing and logistics markets. Quite different from the Passive RFID solutions famously championed by Wal-Mart and others, Active RFID systems are integrated into critical business processes to improve operational efficiency and reduce costs by providing real-time location information about assets and even people. While Passive RFID has held the limelight in the past, Active RFID solutions have in fact been quietly saving millions of dollars for enterprises around the world.

This guide introduces Active RFID with a special focus on the tags themselves, outlining common deployments, defining the competing methods of tag-to-network communication and explaining how to choose the right Active RFID tag to meet your needs.

Unlike their Passive counterparts, Active tags are sophisticated wireless devices, capable of communicating data at long range and operating in rugged environments for years at a time.

Active tags do differ in price, with a wide range available, but unlike Passive tags, price is not the distinguishing factor. Instead, organizations must consider a wide range of attributes and technological factors when selecting the correct configuration.

This guide will help you locate the correct Active tag solution to fit your company's needs.

To start with, a few definitions:

• RFID — Radio frequency identification uses electromagnetic or electrostatic signals to uniquely distinguish and identify a unique mobile "tag" device. Assets can be tracked if the identity of the attached tag is known.
• Active RFID — An identification system in which tags have their own power source (usually a battery), enabling them to broadcast an identifying signal. This extends the range of the tags and the capability for communicating advanced information such as location.
• Passive RFID — An identification system in which the tags are not powered, but rather rely on active signals from the location transmitters for their response. This limits the range of the tags to a few feet.
• RSSI — Received signal strength indication is an algorithm that determines the location of an active tag by measuring the power of radio signals. RSSI typically works best for indoor deployments where the density of active RFID or Wi-Fi readers is high.
• TDOA — Time difference of arrival is an algorithm that determines the location of an active tag through triangulation, measuring the time differences of a single signal received by multiple receivers. TDOA typically works best in outdoor environments or large open indoor environments (e.g. large manufacturing hangars).

Sample uses of active RFID tags include tracking infusion pumps throughout a hospital so that nursing staff and biomedical teams can find them in a timely manner; tracking high-value work in process (WIP) inventory in the aerospace and automotive manufacturing sectors; and tracking trailers and containers in the transportation/logistics industry, both inside a warehouse and around the depot.