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UCSD Students Tracking Their Friends' Locations
An Anonymous Coward writes: "The location-tracking software, developed by a 15-year-old student at the university, draws upon triangulation technology. The PDAs figure out their locations by comparing the strength levels of signals traveling from the devices to various Wi-Fi antennas. No GPS Required. Article from Salon here..."
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I remember seeing a show many years ago about XPARC and how they developed a system that would track an employee anywhere in their office by using transmitters on their ID badges. Problem was nobody would were the badges after they got through the front door because they didn't want to be tracked. Duh.
It's a fun little toy, but it's all fun and games until someone gets hurt. The first time someone gets malevolently stalked over the system, there'll be some crap ont he fan.
I am one of those CS students who receieved a free PDA and I've never seen anyone do anything other than goof around on the internet in lecture with them.
We did however make use of another app called activeclass that was semi-interesting, allowing students to post quetions to the professor during lecture (moderated by a TA). Unfortunately it tended to take so long to input the question on the PocketPC PDAs (which I find to be clunky and sluggish, I ended up giving my PDA to a family member to use) that the question was no longer relevant by the time I entered it.
you can read about it here:
http://activecampus.ucsd.edu/
--Avoid metagame thinking, browse with scores hidden (This sig is in violation of itself)
Does anyone know about a more detailed write up of this?
Specifically, I'm wondering whether each portable device is computing its own location based on the relative intesities of the access points as measured at the device, or the other way around.
If the devices are determining their own position, then, at least in theory, it should be possible to be selective about who gets access to that information. Done properly, there wouldn't need to be any central point of failure, so an attacker would need to compromise the software on their intended victim's PC. Or, more likely, they would have to discover an unintentional fault in that software and exploit it. On the other hand, if an external system is determining the location of the devices, then a would-be snooper need not compromise the software on the victim's computer, but only the central system.
In the first scenario, your own Pocket PC is trusted, while in the second, a device outside your control is. This isn't really that big a distinction in practice, because most of us extend trust to third parties by using software and hardware the properties of which we cannot or do not verify, but it's still important: It's possible to some extent to verify and monitor the behavior of systems in our physical possession, but nearly impossible to do so with someone else's.
A Software System for Locating Mobile Users:
Design, Evaluation, and Lessons
Signal Degradation due to weather and metal isn't so much an issue with triangulation technology because in the case of weather it will just degrade the signal to all antennaes equally from which you can still obtain a differential signal and in the case of a metal wall blocking one antenna, you are still going to be able to track the individual on a line which is all you really need most of the time (still there are so many algorithms that take signal degradation due to obstacles into account. ie every cell phone, you just need to pick the method of choice and bam) One thing I'd like to know is how they effectively sector the antennas on the campus. (Everyone is on the bad site of this tech but say campus security can use it to know the exact position of a victim who is fleeing an attacker, instead of having those polls they have to wait at. i think attackers would be more wary if the student has to only push one button to get campus security tracking her(his) every location)
This sounds similar to the triangulation the cell phone companies tried to use to locate phones when ordered to do so by law enforcement (to comply with CALEA and ostensibly E-911.) That didn't work well enough in rural cell areas, however, thus the move to on-board GPS receivers in cell phones.
The thing that amused me the most was the error in the Salon article's description of the technology involved:
The location-tracking software itself, developed by a 15-year-old student at the university, draws upon triangulation technology used by global positioning system (GPS) devices. The PDAs figure out their locations by comparing the strength levels of signals traveling from the devices to various Wi-Fi antennas.
GPS does not use signal strength. GPS uses differential timing. This system and software work like a GPS in the same way that a kitchen stove works like a microwave oven. Love them Salon facts.
John