I would like to build a simple RFID system to record the in and out flow of files from a room. I would also like to record which individuals remove or return a file, as well as the date and time. What would you recommend?
In general, document-management systems have used passive high-frequency (HF) technology. An Australian company, Magellan Technology, has developed something called "phased-jitter modulation," which enables a user to read HF tags in close proximity to one another. Thus, if you had a stack of files, you could read all of them simultaneously. With ultrahigh-frequency (UHF) systems, you would typically not be able to read all of the tags, because those at the top would block energy from reaching those below.
However, since you are less interested in reading files on a shelf, and more in reading files leaving a room, a UHF system is probably the way to go in your case. There are many companies that offer tags that could be affixed to the files and used in badges to identify a person removing or returning an item. Companies such as Motorola, Impinj and Alien Technology manufacture readers that could be installed around doorways. The only real challenge would involve making sure the system is designed to capture a person's ID badge. Since the human body is mostly composed of water, it can absorb RF energy and prevent a tag from being read.
You will also require software to track which files are checked in and out. A programmer can probably write a simple database program for you, but there are firms that offer full document-management systems with RFID capabilities, such as 3M and TAB's FileTracker.
—Mark Roberti, Editor, RFID Journal
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