Badtux the Snarky Penguin

In a time of chimpanzees, I was a penguin.

Religious fundamentalists are motivated by the sneaking suspicion that someone, somewhere, is having fun -- and that this must be stopped.

Thursday, December 22, 2005

RFID: The Number of the Beast?

Sigh. The conspiracy nutcases are now ranting about RFID. While an *actual* conspiracy exists at the top of our government -- a conspiracy to subvert the Constitution, destroy rule of law, and bring in Imperial government via a permenant Republican majority instituted via fear, intimidation, and control of the voting machinery of America -- they're inventing new and ludicrous "conspiracies" to distract us.

For the record: RFID tags have no power source. They are completely reliant upon RF waves impinging upon them in order to power them. And RF waves fall off dramatically in field strength with distance. I did some back of the envelope computations (won't bore you with them here) and found that for a highly directional RFID reader, practically speaking you have a range of 11 meters (about 33 feet). For an omnidirectional RFID reader, practically speaking you have a range of 3.3 meters (about 4 feet). Anything beyond that, and the signal strength loss means there just isn't enough signal strength to power the RFID tag. Upping the signal strength can get you more range (upping your signal strength from 4 watts to 14 watts will get you ln(10) more signal strength at a given distance, for example, or about 2.3 times the distance), but RFID tags operate in a crowded frequency range and this would cause all sorts of issues with other technologies that use that frequency range.

In short, as a spy technology, RFID tags suck rocks. You either need to be aiming directly at a person like with a radar gun from a distance of 11 meters or less, or have a reader set up so that it will detect RFID tags passing within 4 feet of it. Practically speaking, what ends up happening is that you end up with those semi-directional gates like at the exit of Wally World that detect the tags as you walk through the door (and corresponding pallet-sized gates at the loading dock entry to get the stuff into the system in the first place). Which is fine and dandy if you're Wally World trying to make sure that your pallets have as many cans of Coca Cola as promised and that everything going out the door has gone through a cash register counter and been paid for, but pretty damned useless as a general-purpose spy technology.

In short: given the real conspiracy to destroy America that exists at the very top of our government, RFID is somewhere around a gnat's ass on my list of "technologies that scare the shit out of me".

- Badtux the Electronics Penguin

Posted by: BadTux / 12/22/2005 01:08:00 PM  


well, that's the state of RFID today. the technology can advance of course.
# posted by cinto : 22/12/05 3:02 PM  

Errm, this isn't a case of technology advancing or not. This is a case of fundamental limitations imposed by physics. The fact that field strength decreases inverse to the distance from the transmitter inherently reduces how much energy that you can put into an RFID tag to non-significance with any kind of distance, and this has nothing to do with technology and everything to do with fundamental laws of the universe.

Yes, I actually worked the field strength equations myself, and they match basically what the RFID proponents say, which is good 'nuff for me.

We already have all the technology necessary to impose Big Brother. There's no need for RFID tags to track us all when all that Big Brother would need to do would be to tap into existing "private" and public databases and find out pretty much everything we buy, sell, own.

- Badtux the Science Penguin
# posted by BadTux : 22/12/05 4:40 PM  

true enough about the inverse square limitations, but..
A: add a small capacitor/chargeable cell to the tag
B: give it remote trigger (send data - now) capability
There are still limitations.. must be periodically recharged, etc, but we have a whole new game..

IIRC, Intel (?) is coming out with new semiconductor technology which requires lower E & I (& that makes P! ;-))..

But, you are still correct.. we already have conspiracies to worry about..
# posted by bobby : 22/12/05 7:09 PM  

Well, the problem with adding batteries (or their cousins, electrolytic capaciters) to RFID tags is that they are a) expensive, and b) run down. The reason retailers like Wal-Mart are so keen on RFID tags is because the tags are dirt cheap -- basically tiny silicon chips in a very inexpensive package -- and will greatly ease their inventory management (and reduce lossage drastically). If you make the tags expensive and with a limited life span, they're no longer interested in having them embedded into every little item that goes through their store.

I'm sure that the FBI/CIA/etc. already have RFID-like tags that include their own power source, and have the ability to read these from some distance away. This is not "Big Brother" though because they must a) target someone, and b) do a sneak-and-peek to plant the bugs on various clothing items etc., which makes them no different from any other kind of bug. The deal with RFID is that eventually *everybody* is going to be wearing RFID-tagged items, meaning that people's movements could be tracked by hacking in to say the gates at the entrances and exits of stores. But you can already pretty much do that now by tracking credit card and checking account transactions, cash is not used as often nowdays as it once was. So RFID itself is not of particular paranoia-inducing quality to me, especially given the very *real* conspiracies that are currently underway in Washington D.C....

- Badtux the Practical Penguin
# posted by BadTux : 22/12/05 9:48 PM  

for a penguin, you're pretty sharp.. ;-)

Yes, Wally World wants the cheap tags.. & for them, they are good enough.. As for 'where to hide the tags'.. Very soon now, I expect "Your papers, please" to be implemented.. with an RFID type tag included..
In the BBC today,
[Japanese company NEC has developed a lightweight, flexible battery that is less than a millimetre thick and can be recharged in half a minute...

ORBs could eventually be embedded into devices such as smart cards, wearable computers and intelligent paper.

Currently the battery, when in card form, can be recharged with a card reader device in 30 seconds.]

Of course, if the location of the device is known (within a passport, for example) one can always 'destroy' it (a microwave comes to mind) or even 'forget to carry it', which will likely carry a penalty, just as driving without a license does in most states.

Please remember, some of us still use only cash.. Which brings up another thing I expect to see changed 'real soon now'.. The major short comming to a plastic based society is how do we pay the kid next door to mow the lawn? If the kid can't get jobs, how will (s)he learn about the wonderful world of societal sharing called 'work'? Do the powers that be care?? Yah, right.. Libertarians know better.

Now that I've spouted all that ;-), there is, of course, a difference between RFID (passive) & Smart Card (active) technology. This could be the basis for your focused commentary on RFID, in which case, Oops, my bad! ;-)
# posted by bobby : 23/12/05 7:57 AM  

The major short comming to a plastic based society is how do we pay the kid next door to mow the lawn? If the kid can't get jobs, how will (s)he learn about the wonderful world of societal sharing called 'work'? Do the powers that be care??

I live in CT, and I'm here to tell you that with the exception of babysitting, all those jobs that we used to do as kids for Christmas money, (lawn mowing, raking, making wreaths, delivering newspapers) have been taken over by adults, and are not being done by kids anymore. More the shame...
# posted by SB Gypsy : 23/12/05 8:49 AM  

practically speaking you have a range of 11 meters (about 33 feet). For an omnidirectional RFID reader, practically speaking you have a range of 3.3 meters (about 4 feet).

Hmm... maybe you do need to bore us with those back-of-the-envelope calculations you did... Here in the midwest (where you get all 100 cemtimeters from each meter) 3.3m=11ft.
# posted by Anonymous : 4/1/06 10:35 PM  

Hmm, I don't know if I was trying to say 1.3 meters or 3.3 meters. If the former, then 4 feet is right. If the latter, then 11 feet is right. Frankly, I don't care enough to go dig up the calculations I ran and post them here. I simply took the field strength equations, computed the energy necessary to return a numerical signal in the legal frequency range for RFID, and computed the point at which the field strength of a RFID transmitter would be insufficient to power a simple chip returning the ID via RF where I made certain assumptions about receiver sensitivity transmitter energy usage etc. I.e., very back-of-the-envelope. Frankly, I don't care enough to go back and look up those equations again.

My basic point -- that the fundamental laws of the universe contraindicate RFID as a useful "Big Brother" mechanism for keeping tabs on people's movements on a large scale, and that other technogies (such as, say, the NSA spying on every domestic phone call?!) are more worrisome, remains true whether it is 4 feet or 11 feet.
# posted by BadTux : 4/1/06 10:56 PM  

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