Important Considerations for RFID Geiger Counting
One of the most widely used RFID applications is Geiger counting, which is used to locate specific tags in densely packed environments using mobile devices. Mobile RFID readers typically carry software for locating tags, and when an RFID reader gets close to a searched tag, a ticking sound can be heard – hence the name Geiger counting. The ticking sound gets faster as the RFID reader moves closer to the tag. This can be used to find a pair of jeans in a particular size within a store or to track down a box that has gone missing in a warehouse.
While Geiger counting makes use of tags’ RSSI values to determine their proximity, it’s important to note that the more the transceiver sends out RF energy, the higher the strength of the signal that the tag gives off. That’s why good Geiger counting practices must entail adding the output power to the calculation. When the reader notes a very high possible RSSI value, it can lower its output power to see if it still notes the same signal strength. If that is the case, it should continue dropping its power until reaching the lowest possible setting. If the RSSI value becomes low enough, the application should increase the output power. However, if the strength stays up under low output power, it’s safe to assume the tag is quite close to the reader itself. When devices have more than one antenna mode, both can be used to boost the accuracy of determining the tag’s proximity.
Many of the mobile RFID readers that are currently available on the market can handle tag locating software. Accuracy can be maximized when locating particular tags by using a mobile RFID reader with as narrow of an antenna beam as possible. Most models come with an omni-directional antenna beam, which means that software will often be needed to control the beam.