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Topic: limitations of using multi rfid readers and cards in the same range (Read 1 time) previous topic - next topic



I'm planning for a wearable rfid project, put 1 reader and 1 tag on each t-shirt's sleeve.
When 2 users are shaking hands, the reader on each read the card of another.
Reader: Innnovations ID-2, 125kHz read frequency from http://www.sparkfun.com/products/8709
Tags: 1K and 4K, 125kHz

A question relating to the demonstration video here http://www.sparkfun.com/products/8709
Does the reader read 2 tags one after another, if the tags are not put together in stack?

Also, i found another limitation of using 2 or more readers in the same range from http://bildr.org/2011/02/rfid-arduino/
It says "more than one reader right next to each other can cause none of them to work due to interference."

Anyone has a solution for using 2 readers (next to each other) to read 2 cards?



The ID-12 reader, which I have, reads two cards if presented about a second apart.

Also I doubt it would work with two readers near each other because they will both be transmitting radio waves (the RF part of RFID) and they will interfere with each other.

What might work with your project would be to randomly turn the reader on (eg. for 1/4 of a second) and see if a card is there. Then turn it off to give any other readers nearby "a go".

Your other problem would be that as people shake hands the reader is just as likely to read his own ID rather than the friend's ID.
Please post technical questions on the forum, not by personal message. Thanks!

More info:


Thank you for the advice Nick.
I'll try 2 readers in the same range and post the result here.



The range of most RFID readers is pretty limited. Having one on a sleeve, with a tag on another sleeve, with the wearers shaking hands, is probably NOT going to get the tag and reader close enough to trigger a read.
The art of getting good answers lies in asking good questions.

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