RFID and GPS: Complementary Technologies
RFID and GPS are two different technologies that can be used together to create new and innovative applications. In the highest terms, RFID tags are used to identify assets and GPS tags can be used to keep track of that asset’s location.
RFID: Who am I?
RFID (Radio Frequency Identification) is terrestrial-based and consists of two major components: the RFID tag and the RFID reader. The reader can only read the tags when they are in relatively close proximity. Once the RFID reader reads the RFID tags, the data is sent to the RFID middleware with a database. The tagged asset can then be tracked on its journey from the warehouse to the checkout at a store. For example, the tag could be checked out at the loading dock of the manufacturer, again as it reaches the store’s distribution center, once more as it leaves, again as it arrives at a local store, and finally as it leaves through the register after being purchased. Each time the asset is read, the tag is recorded in the database. This gives the information needed about where the product is so more informed decisions regarding supply and demand regarding inventory levels can be made.
RFID provides identifying information on a tag that can be read by an RFID reader using radio frequencies. This information includes an ID that uniquely identifies the tagged asset. In some RFID applications the reader can use the strength of the returned signal from the tag as a locator, especially when used with multiple readers to triangulate the position of the asset.
There are three types of RFID tags:
- active tags that contain a battery and are constantly transmitting data
- passive tags that require external power from the reader to reflect the signal. They do not contain batteries
- battery assisted passive tags that function as something of a hybrid of the two in that the reader is required to activate the battery functions
RFID technology is best suited for smaller, contained areas, where the infrastructure is already in place to use it. RFID requires specialized readers to read and transmit data. The dedicated infrastructure can be incredibly effective for both tracking and for providing data on an enterprise’s assets.
GPS: Where am I?
GPS (Global Positioning System) is satellite-based and consists of two components: The network of satellites circling the Earth and the GPS receiver. The GPS receiver has its own onboard computing capabilities used to receive signals from the satellites and determine its own location based on those signals; it then relays that information to the navigator. The GPS receiver can be no smaller than two D-cell batteries, and it must have an antenna or be exposed to the sky in order to receive signals from multiple satellites.
Like RFID GPS also uses radio waves to transmit data using the global positioning system of 24 satellites, as opposed to specialized readers here on the ground. Radio waves sent out from the GPS system of satellites transmit their time and orbital data to receivers down on Earth. Using the data from multiple satellites, receivers can then triangulate their position relative to the satellites, and thus place a tag’s location on the Earth’s surface.
GPS is best suited for tracking assets anywhere in the world. But because of the sheer distance of the satellites, the GPS signal can be weak. Civilian models particularly are not as accurate in certain situations as one might like for a particular application (e.g., at the bottom of a canyon, indoors).
Emergency homing beacons, car trackers, or navigational devices tend to be the most well-known civilian uses, which do not require accuracy within a few inches, but happen on a large scale where no other infrastructure such as RFID or radio towers are set up. GPS is, by definition, global, and so the sort of tracking it is best at usually happens on the larger scales.
RFIID and GPS: Real time asset tracking
Companies are increasingly leveraging a mix of RFID and GPS technologies to track critical assets that need to be monitored on a near constant basis. Specialized tags with embedded GPS receivers can transmit their location coordinates via satellite or cellular data links to a central server.
New combination tags contain both an embedded GPS and a passive UHF Gen 2 RFID tag in a single package. The passive RFID tag can be used to read at short distances when going by an RFID reader and the GPS position reporting satellite transponder can provide an update on the asset location when the asset is on the move beyond the RFID read range. Tags can also report their GPS position using cellular data links if the asset is going to be moving around in locations that are covered by existing cellular infrastructure.
Got any great ideas on how RFID and GPS can work together? Let us know in the comments!