11 Aug 2009 09:09 UTCTue 11 Aug 2009 - 9:09 am UTC
Related to http://uclue.com/?xq=3177 (but don't focus on the pet connection).
How can you nefariously stop a GPS tracking device from transmitting its location. I am thinking about hacking into it, or putting something like silver foil around it (I made both of those up). I don't know if a look at how car alarms work may be relevant.
I am not interested in how you can physically tamper with the device. Assume you cannot touch the device.
11 Aug 2009 13:09 UTCTue 11 Aug 2009 - 1:09 pm UTC
Have you tried a film pouch, the kind used to protect your film at airports?
Sima FSM Film Shield-Extra Strength Mini Pouch
Film bag with an x-ray shield
Guards against airport x-ray damage
Protects up to 3 rolls of film at a time
Lead foil bag with a polyester outer layer
Plastic clasp seal for easy closure
11 Aug 2009 13:11 UTCTue 11 Aug 2009 - 1:11 pm UTC
Patricia, no, I haven't - would that work?
To clarify, what I am interested in is how someone who might really want to disable the device could do so, rather than how I might do so as a matter of curiosity. The former is going to try harder and be more determined.
11 Aug 2009 14:12 UTCTue 11 Aug 2009 - 2:12 pm UTC
Montecristo, I think the lead pouch would work but couldn't they just remove the battery? Patricia
11 Aug 2009 14:37 UTCTue 11 Aug 2009 - 2:37 pm UTC
No, they cannot remove the battery. "I am not interested in how you can physically tamper with the device. Assume you cannot touch the device."
11 Aug 2009 14:43 UTCTue 11 Aug 2009 - 2:43 pm UTC
Whoops, sorry. P
12 Aug 2009 09:37 UTCWed 12 Aug 2009 - 9:37 am UTC
Looking at this from the point of view of the physics of the device, here are the possible ways to block the operation of the GPS tracking device without touching it:
1. Block the incoming GPS satellite signal.
2. Block the outgoing transmitted signal.
3. Jam the incoming GPS satellite signal.
4. Jam the outgoing transmitted signal.
5. Isolate the unit until its battery is discharged.
6. Damage the device to render it inoperable.
7. You could also sabotage the receiver, but that may not be within your remit.
(1) Blocking the incoming GPS satellite signal is the easiest. Patricia's suggestion of a metal film pouch will absolutely work 100% reliably. Incidentally, a bag made of metal mesh (say 1mm spacing) would work just as well as a metal-lined film pouch. If the GPS device is in a known orientation (e.g. attached to a car or even to a known position of a dog collar) it would probably be enough just to put a sheet of metal between the receiver and the sky but you would need to test this "in situ".
(2) Blocking the outgoing transmitted signal. A film pouch will work fine, but a single sheet of metal probably wouldn't, due to the higher power of the outgoing signal compared to the very weak incoming GPS signal.
(3) You could jam the incoming GPS satellite signal by broadcasting a "fake" GPS signal. This is no doubt illegal and could cause danger to other GPS users.
(4) You could jam the outgoing transmitted signal with a fake signal. If your transmitter is close to the (fixed?) receiver, it can be a very low power transmitter. Probably illegal.
(5) If the battery of the GPS tracking device is discharged, the device can't operate. All you need is time for this one to work.
(6) You could damage the GPS tracking device without touching it in a number of ways. Exposing it to excessive heat (e.g. from a hair dryer) should do the trick. It's potentially dangerous - beware of fumes and exploding batteries! Some units would fail after being drenched with water, or something more corrosive. A high-voltage electrical spark across the device would probably also work. Squirting glue into the battery charging connector (or battery compartment) would put the device out of action after the battery runs down.
(7) You could damage the receiver in similar ways.
I don't know of any practical way to hack into a GPS receiver and modify its firmware unless you have physical access. So reprogramming the device covertly is unlikely to be practical.
At this time, I'm not in a position to put this together into an answer with references, links to devices and instructions, etc. If you just want a general overview like this (e.g. for a book plot), let me know and I'll post this as the answer.
If you need something more specific, please let us know your needs and perhaps another researcher can take it forward to meet your requirements.
12 Aug 2009 11:09 UTCWed 12 Aug 2009 - 11:09 am UTC
Thanks for letting me know that the information provided above meets your needs.
12 Aug 2009 11:48 UTCWed 12 Aug 2009 - 11:48 am UTC
So is the reason that GPS works in a car, that there is a window? Could I not run GPS inside a tank, say?
12 Aug 2009 18:42 UTCWed 12 Aug 2009 - 6:42 pm UTC
Yes, car GPS depends on receiving a GPS signal through the car windows.
GPS receivers which are made for use in environments without a clear view to the GPS satellites will include an antenna socket. This can be connected to a GPS antenna mounted outside the shielded area.