Also, what exactly does the received signal strength indicator measure?
Received signal strength indicator (RSSI) is a measure of the strength of a signal received from a tag. I assume you are talking about passive UHF RFID systems, which use RSSI to determine how close a tag is to a reader antenna. The answer to your question depends on what you are trying to achieve.
If you were to install a fixed reader with antennas around a dock door, you might be concerned only that you read a tag on a pallet moving through the dock door. In that case, RSSI might not be very important. If, however, you were using a handheld reader to locate a tagged object within a store, then RSSI would be critical since it would tell you whether you were moving closer to the tagged item or further away. Handhelds typically beep louder or more frequently as the signal strength from a tag increases, indicating that you are nearing the tag.
—Mark Roberti, Founder and Editor, RFID Journal
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