Can you please explain how these two technologies differ?
General packet radio service (GPRS) is a cellular phone communication method used by 2G and 3G systems. There are active radio frequency identification tags that use GPRS to send sensor information back to a base station via the cell network, and tags can also send GPS coordinates over that network. These tags are used on trucks traveling the open road, to provide shippers with knowledge of where a specific vehicle is located at any given time, as well as the conditions of the goods inside.
Active and passive RFID are, by contrast, much shorter-range technologies. Passive ultrahigh-frequency (UHF) tags have a read range of about 20 feet to 30 feet (6 to 9 meters) and can tell you when a tagged object is within that distance of a reader or has passed through a read zone. Active tags have a much longer read range, typically 300 feet (91 meters) or more. They are used to locate an object over longer distances than passive tags, but much shorter distances than tags that use GPRS.
So a company shipping fresh produce, for instance, could put a passive tag on each container and an active tag with a temperature sensor and GPRS connection on a stack of containers. The passive tags would tell exactly how many containers and which ones were loaded onto the truck, while the active tag would monitor the temperature within the compartment. This information, along with the vehicle's GPS coordinates, would be broadcast via GPRS to a cell tower and relayed to a base station. Thus, the shipper would then know the temperature of its goods and the locations of any trucks transporting them on the open road.
—Mark Roberti, Founder and Editor, RFID Journal
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