Radio frequency identification technology uses "tags" which broadcast encoded identification information. The most common type of RFID tag is the passive tag, which only transmits when it receives a signal of the proper frequency. However, there are active RFID tags, which contain an integrated power source and broadcast constantly or at regular intervals. These are more expensive than passive tags, but the more frequent updates and increased range makes them more useful in certain specific applications.
Sensor Tags
One area where Active RFID is preferable to passive systems is in tags that are associated with some kind of sensor. Sensor tags are useful for measuring temperature, as with heating and cooling systems or temperature-sensitive substances like pharmaceuticals, but there are also tags that measure ambient light, humidity, or any other condition requiring regular monitoring. Since active RFID tags already contain a power source, the sensor can use the same battery for power.
Personnel Monitoring
Active RFID tags also find use in monitoring the locations of personnel in high-security settings. Active RFID security badges can provide an up-to-the-second image of where everyone is in a facility, allowing specific personnel to be located quickly and easily should the need arise. These systems can also automatically open doors and disengage security measures when a properly cleared person approaches a security station, and they can identify when someone is in an area they should not enter. Hospitals also use active RFID to track patients, and they can include biological monitors to keep track of heart rate, respiration, and other important factors during recovery.
Security Systems
Electronic security is another application where active RFID tags are very useful. Attaching RFID tags to valuable items and equipment allows security personnel to track and monitor them from a central location, and quickly determine if anything is out of place or missing. These active tags can also trigger alarms when taken out of designated areas, and can even provide tracking information once outside to allow security personnel to quickly recover stolen goods.
Shipping
Many shipping companies, ports, and transport terminals use active RFID to track containers as they move from place to place. Constantly updated location and destination information helps reduce shipping errors, preventing deliveries from being misrouted and saving valuable time. The extended range of active RFID allows permanently mounted sensors to track the contents of entire warehouses at once, reducing the need for employees to scan items manually as they enter and leave the building.
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