On Wed, 10 Apr 2002, Eugen Leitl wrote: > The tags are passive. All tags (whether inductive or electrostatic) must > be energized from the outside. The pumping energy can be shielded, as can > the RF emission of the tags itself. The environment is noisy. The tags > send simultaneously from the same physical location. > > I'm not sure whether microwave-pumped digital pulse radio based tags > (currently no such technology officially exists) could have a somewhat > wider range and less crosstalk, but even then they could be shielded. > > On this background, the particular technology one uses is not very > relevant, as we're talking about limits of physics. Reading secreted > banknotes on your body with a magic wand reader is easy (unless wrapped in > metal foil), reading them from across the room -- no, sir.
That's true for all RFID stuff, but the next generation the military is looking at is called "smart dust". The idea here is to have each speck send info, and the conglomeration of specks adds up to a large signal which can tell you something about the environment (like presense or movement of large metal objects). It's all sci-fi for now, and I think they'll still have to power the things externally so the same shielding applies, but if the bill holds enough transmitters it could have a longer range. But there's no reason a commercial object couldn't have an off switch and power supply built in - the whole "wearable computer" thing is aimed at that sort of application. All we gotta do is prove to the wealthy they can get more wealthy, and we get to play with the toys :-) Patience, persistence, truth, Dr. mike
