Hi all,
Can any one tell how can I manage mutual exclusivity of two HF-RFID readers(13.56MHz) which are seperated by a short distance (around
20cm). I want RFID readers to read only the tags present in their specified zones. How is this possible ? Will I have to operate both readers at different frequencies and then tune their associated tags to the corrosponding frequencies ?regards ashu
You can simply reduce the Tx power or detune the antenna and thereby reduce the read range. Most practical applications of this type don't have read ranges ANYTHING like 20cm anyway - you will have no problems meeting this requirement.
I doubt you can tune the tags unless you're building them yourself. How quickly are the tags moving? Since it only takes several ms to read a tag, maybe you can operate the readers alternately so reader 1 is on half the time and reader 2 is on half the time. Are you also concerned about reader 1 picking up a tag in zone 2? If so, you might need to lower the power output of both readers.
You've mentioned the distance between the readers but not their intended orientations. I.e., are they both "watching" the same region of space for a tag? (doubtful) If not, can you put any RF barriers to help attenuate the (potentially) "shared" signal path? (e.g., two readers on opposite sides of a wall behave differently than two readers "focused" on the same spot)
You can use time division multiplexing to gate the excitation from one soas not to interfere with that from the other (i.e., so the tag only "sees", at most, one at a time)
Aside from not *wanting* "the other" reader to see a particular tag, is there anything *about* the tag that indicates which reader is *intended* to see it? I.e., can you post-process the information from the two readers to discard information they "weren't supposed to" see?
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