Tuesday, March 26, 2013

More Technology Than I'm Actually Comfortable Explaining

Now, dear readers, don't get me wrong. I know a lot about the internet and how to use modern technology. I thoroughly proficient at tumblr and my smartphone and how to access youtube through my Playstation 3 and I can use an excel sheet like nobodies business. But when it comes to how these things actually work, I'm less useful than an astrolabe on a cloudy day. I'm not technologically minded. I can fix my a/c and install a basic power outlet, but in 23 years of following my electrician father around his work, I still can't really tell you how home wiring works. I've no issue being functionally ignorant of these things, just as I figure it's okay to not know architectural engineering. But I feel like I owe it to you, dear readers, to try and get to the nitty gritty nuts and bolts workings of RFID tagging as I possibly can. Which isn't all that much.

First we're going to talk about frequency. As RFID's name (Radio Frequency Identification if you've forgotten) suggests, each tag sends out a radio frequency that can be heard or more accurately read by a receiving device. The higher the frequency it sends, the further the signal can go without losing coherency, meaning the further away it can be read. This also means the closer the reader is to the tag the quicker it can read it. There are three general frequency areas for commercial tags, low, high, and ultra high. Low frequency must be read quite closely to be read at all, becoming unrecognizable at distances of at most 3 inches generally depending on the type of reader. This type of frequency might seem useless for library application which requires an amount of distance, but it is exactly the type of tag that is used in certain ID cards much like the technology you can find in my VSU 1card. High frequencies are the type more likely to be found in library tags since they can be read at several feet given an appropriate scanner. Ultrahigh can be read even further but to produce ultrahigh frequencies the technology needs to be much larger making them impractical.

Then there is the issue of active versus passive tagging, which refers to the power source of the technology within the tag. Tags that are actively powered can be considered always "on", always emitting a signal which makes them that much easier to read. They are always larger and much more expensive. Passive tags are powered by the signal sent out by a reader, sending signals only in reaction. It means that these signals take more time to read and that their reading ability hinges on the type of reader activating them, but it also means they are slimmer and easier to hide in books. They are also cheaper and way more common because of it.

Now when in comes to readers, there's typically three kinds as far as libraries go. There are the desk scanners, which have some of the portability of handheld scanner but much more power. These are wired to a computer and typically used in circulation or on conversion stations and to activate or deactivate security measures coded in tags. There are the handheld scanners which have decreased range and processing ability but can be easily moved through the stacks to aid tasks like taking inventory or weeding collections. Handheld and desktop scanners can be used to write coding on tags if the tags are equipped to be written. (I'll do a post on coding later I think.)Then there are the security sensors which read the tags as people come and ago from the library. They have superior range but no mobility. They also have to send out a constant field to activate passive tags, unlike the other kinds that typically only read on command. Though I generally think of them as the sensors you see at the exits of libraries, some libraries have them placed in book drops to automatically check in returned materials. Some of these book drops have connected automated book sorters that read the tag on a book and designate it to a pile to be reshelved in a certain area. I've never actually seen it done outside of the German video a way back.

 That's all I can think to include about the major technology at present. I'll post a sequel to this eventually explaining some of the technology on a tag itself if I ever figure out how it works.



References

3M. (2013). RFID 301. Retrieved from http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UgxGCuNyXTtnXTtnxfEEVtQEcuZgVs6EVs6E666666--&fn=RFID%20301.pdf

American Library Association. (2011, October 10). RFID technology for libraries. Retrieved from http://www.ala.org/pla/tools/technotes/rfidtechnology

BarcodesInc. (2013). RFID Buying Guide. Retrieved from http://www.barcodesinc.com/info/buying-guides/rfid.htm

Bhargava, H., Campbell, A., Das, A. M., Haines, B., Kleinschmidt, & J.Thornton, F. (2006). RFID security. Rockland, MA: Syngress Publishing. 

Chatterjee, R., Choi, J., Park, S., & Wolfe, P. (2004). Proceedings from IIE Annual Conference: Evaluation of using RFID passive tags for monitoring product location / ownership. Norcross: Institute of Industrial Engineers

Pandian, M. P. (2010). RFID for libraries: A practical guide. Oxford: Chandos. 

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