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I did the teardown, and I'm a regular hacker news reader. I'll answer any questions for the next hour or so.
by kwiens 15y ago
I did the teardown, and I'm a regular hacker news reader. I'll answer any questions for the next hour or so.
- 18pfsmt 15y agoVery cool. Have you all done any firmware/software hacking?
- evilpie 15y agoCould you estimate the price of this thing, as the FBI told him it was expensive (and at least the batteries seem to be).
- 18pfsmt 15y agoOff the cuff BOM for this thing is on the order of $30 in 1K quantities (maybe add 20% for government bureaucracy).
- kwiens 15y agoFor the manufacturer, maybe. But then you have to factor in bribes to the federal procurement officers and junkets to Atlantic City to land the contract, and then medical payments for the workers who burned themselves hand-soldering resistors on that board. That's gotta up the price to at least $3K/unit or so! :-)
- HeyLaughingBoy 15y agoCan't really. Cost of BOM bears no relationship to selling price. His post below says it costs about $30 in 1k quantities. So estimating about $50 in 10pc prices, if I were building a few for a government agency/large corporation, ignoring NRE charges I'd probably price them upwards of $1000 each. This is not exactly something you can purchase at Best Buy...
- kwiens 15y agoWe have not—I had limited time with the device at Wired's office. We powered it on and used a frequency analyzer on it, but that was the extent of our investigation. We were concerned that black helicopters might show up if we left it on too long. But I hope someone else does!
- huhtenberg 15y agoDon't you guys have a Faraday cage for this sort of teardown?
- kwiens 15y agoWhat, you mean for all the other devices we take apart that regularly phone home to their manufacturer, who would show up at a moment's notice in a black helicopter to put an immediate halt to our technical analysis? Of course! We have to block RF transmissions all the time!
- burgerbrain 15y agoDidn't Apple have that one reporter guy who was sent the 'lost prototype iphone' SWAT'd?
- dgallagher 15y agoWhen do you expect to find one of these stuck to the bottom of your car? ;) In all seriousness, do you believe it would be possible for the FBI to make a similar device to use on bicycles (inside handle bars), motorcycles, scooters, or Segways?
- asmithmd1 15y agoSo this tracker does NOT use cell connections? A receiver would have to get whitin range to download tracking data?
- kwiens 15y agoCorrect. There's specs on the short-range transmitter here: http://xemics.com/docs/xe1200/xe1201evk_userguide.pdf http://xemics.com/docs/xe1200/xe1201evk_userguide.pdf Now this is an old device, and they very well might be using cell phone transmitters now.
- chopsueyar 15y agoYou mentioned it works in the 400MHz band.
- rorrr 15y agoDo you know the range, roughly?
- mikecarlton 15y agoDo you know the maximum range the transceiver can transmit? The datasheet gives lots of design guidance, but nothing specific. Data sheet: http://www.datasheetarchive.com/pdf-datasheets/Datasheets-40/DSA-798216.html http://www.datasheetarchive.com/pdf-datasheets/Datasheets-40... App note: http://www.datasheetarchive.com/pdf-datasheets/Datasheets-314/482157.html http://www.datasheetarchive.com/pdf-datasheets/Datasheets-31...
- kwiens 15y agoI don't know, but perhaps an RF engineer could weigh in given the frequency and transmission power.
- tomsaffell 15y agoIs there a legal way to block them? Either the GPS signal, or the transmitter? (I'm assuming tampering with the device directly is illegal).
- kwiens 15y agoSure, just transmit stronger white noise on 433.92 MHz. I haven't looked up who owns that frequency and whether there are restrictions. Or get a GPS blocker. Which I think are illegal to operate.
- a1k0n 15y agoAFAIK 433MHz can be used for any short-range application, similar to 27/49MHz for R/C cars. There are plenty off-the-shelf 433MHz transceivers for hobbyists, and I think car remote-unlockers use that band as well. And this doesn't appear to have a particularly powerful transmitter, so you'd have to bring the transmitter relatively close to the receiver (like <100ft, usually) in order to download...whatever. If they're able to put this thing on your car in the first place, I guess it's not infeasible for them to drive by to download updates.
- paulgerhardt 15y agoSparkfun sells 434 MHz transmitters for $3.95 [1]; just hook it up to a coin cell or four, and you should be good to go. [1] http://www.sparkfun.com/products/8946 http://www.sparkfun.com/products/8946
- antihero 15y agoI wonder what would happen if you took it off and attached it to a random other car. Then the FBI would be tracking someone else illegally, in theory.
- hartror 15y agoI would bet intent is part of the law.
- yason 15y ago
- Entlin 15y agoDoes it use military mode (the one that is even more precise than regular GPS)? Now that would be great reverse engineering project :) Where was the GPS receiver mounted? These things need view of the sky, no?
- kwiens 15y agoI don't know the answer to either of these questions. It appeared to be a standard GPS receiver, but some investigation would reveal whether the manufacturer supports military mode. http://docs.google.com/viewer?a=v&q=cache:7hhk_GsNmTQJ:www.qsl.net/d/dk7nt//gpsrx/gpsms1.pdf+u+blox+ms1+gps&hl=en&gl=us&pid=bl&srcid=ADGEESjYb3KyvNV-5XoxaKUZziNTjPhBtDzSjim37UgWzSjGAZaZoy2t_e7z0vYXjyd71JHDfJp_0ju3qRDigHxfw6DJKds49In1AH68e3kz9pa9RRyHu2xirykZSbCgbhM8yH_klN2q&sig=AHIEtbQ_Njl7T0SRfbJFmJzCO12_gdVAjA http://docs.google.com/viewer?a=v&q=cache:7hhk_GsNmTQJ:w... I never saw it on the car, but the antenna mount had a hinge that would allow it to stick out from the side of the car. But that would be rather conspicuous—I think that's why the antenna is so large.
- Estragon 15y agoWhat protocol is it using to transmit the location? Is it encrypted or authenticated? (Could it be spoofed?)