When passive tags and fixed portals are deployed (such as for a dock door), could the received signal strength indicator values be of any use in trying to eliminate bounced reads? For instance, could we turn down the sensitivity setting and reduce the RSSI?
You could use the received signal strength indicator value to filter out stray reads using software. That is, you could create an application that would take the RSSI value at the time of each tag read and have it pass along to a back-end system only those tag reads with a strong RSSI value (indicating tagged items that were close to the antenna and were meant to be read), while not passing along reads associated with low RSSI numbers.
However, this probably would not be the best way to deal with stray tag reads because RSSI numbers are imperfect due to multipath problems (in other words, the RSSI value from a tag farther away could be higher because the signal bounced off of some metal in the environment). The best way to deal with stray reads is to attenuate the antenna output so that you are not reading tags beyond the intended area.
If this doesn’t work, I would recommend shielding. Simply using a sheet of Mylar to block energy from the area where you are getting stray reads should solve the problem. I hope this answers your question, and I hope to see you at RFID Journal LIVE! 2020, where you could talk to a variety of companies about the issue you are facing.
—Mark Roberti, Founder and Editor, RFID Journal
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