Is it possible to detect a GPS device planted on your car with some sort of electronic sweeping device? The legality of warrantless tracking is not yet settled, and I’m guessing that any criminals who suspect they’re being tracked might try to circumvent the authorities.
Actually… You should probably read U.S. v Jones:
http://caselaw.lp.findlaw.com/cgi-bin/getcase.pl?court=US&navby=case&vol=000&invol=10-1259
ETA: Tried to fix my link.
For vehicles I thought it was.
Google GPS Detector and some items come up. Whether they are effective or not I don’t know.
It’s very difficult to detect something receiving GPS signals. You’d have to catch it transmitting the information to whoever planted it. That can be done in a ton of ways, but in theory you might be able to get a broad spectrum analyzer and try to find something.
GPS transmitters are extremely easy to detect, but you won’t succeed in removing any of them without being able to knock something out of Earth orbit.
Well…there is that.
As I understand it, most GPS trackers simply record the movements of the vehicle over a certain period of time and then are retrieved for playback. An active transmitter powerful enough for a useful receive range would require larger batteries (unless wired into the car) and would be bulky enough to find by simple inspection. Either way, the GPS antenna requires a clear view of the sky so placement locations are limited.
I think most of this is incorrect. Here’s an example of a basic tracker:
http://www.spygeargadgets.com/gps-rental-xtremetrak-gps-portable-live-gps-tracker.html
Notice it has a magnetic case for mounting underneath. And I believe it uses cell reception to provide next-to-real-time updates. Battery is similar to a cell phone battery.
Now can you find it by simple visual inspection? Maybe. If you know what you are looking for (or don’t know what you are looking at).
Guys, most cell phones nowadays are GPS trackers. They receive GPS coordinates from satellites and, if configured, upload said data to cell towers for potential processing.
If I left my Blackberry in my car, and the car was stolen, the police would be able to (through applicable legislation) attain these data.
So, detecting a GPS tracker would be like sniffing for cell phone transmissions: whatever frequency that goes out on.
A cell phone works in a car, GPS trackers are mounted in wheel wells to track people and the first thing to do this (on a regular basis and readily available to civilians) was LoJack which, IIRC, could be mounted pretty much anywhere and was pretty small AND it transmitted back to, um, somewhere so that you could figure out where your car was. I believe the LoJack transmitter is pretty small.
My Android phone has a free app called Lookout. With it I can find where the phone is, or was before being turned off. Last year my car was stolen with the phone inside. Once I was able to get to a computer, I was able to track the phone to within about 100 feet of where it was located.
So basically anyone could turn a cheap cell phone into a GPS tracking device. Therefore tracking cell phone frequencies would probably be a place to start in locating such a tracking device.
There are two ways of tracking a cell phone: GPS, which uses GPS satellites and needs a clear view of the sky, and measuring the strength of the phone’s signals to nearby cell phone towers. The latter works anywhere you have service; the phone company has to know approximately where you are so it can decide which tower should handle your phone if you make or get a call.
This is pretty funny.
I don’t know how well one of these would work on a car, but here is a detector.
I would imagine there are sweeping devices that can detect active electronics. A GPS receiver likely is a receiver, not a transmitter (unless it sends out updates; alternatively, it could record at intervals and and store that information for download on retreival. If it only made an update in a burst every 10 minutes or so, it might take a while to detect.
Howevr, any active elecronics produces some signal. Digital devices are especially noisy; one of the biggest issues when getting FCC approval for a device is to show it limits emissions that cause interference with other devices. Some radios have characteristic IF frequnecies, to mix with the incoming signal to produce a beat output thatc an be decoded. This is how radardetector detecots work, looking for the characteristic IF leakage of a microwave device.
If I were making a GPS recorder, I’d set it up to turn on briefly every minute or two to note location then shut down; this would make it less likely to be detected.
Classic “bug sweeps” look for any indication of electronic activity, since an electric current produces a magnetic field. The only ones buried in the walls should be power lines. (Except now we have cable TV, ethernet, etc.)
I read that the Federal govt was appealing the decision. I thought that made it “not settled.” Apologies if I misstated the facts.
Signal strength was how the old analog systems did it. Thus the network might try to switch you between towers when you went under an overpass, or past a big building. And could get really screwed up by airborn users hitting several towers with a strong signal.
Digital phone networks require precise timing to work. Thus the network can compute your approximate (limited by network time resolution, which is pretty good) position by timing the arrival of your phone’s signal at various cell towers, or possibly even by telling your phone to measure the timing of the tower’s transmissions. They can even do out-and-return timing, so even if only one tower can see you, they know your distance.
It is a bit crude, but it is plenty good enough to keep the phone using the nearest tower, even when passing through a cold spot. What it also does is allow the cell company to map their coverage using their customers phones. No longer any need for any special “can you hear me now?” guys. Add in GPS, and you get even more detail.
There’s a lot of misinformation about GPS. The GPS systems itself does not need earthbound transmitters. The only transmitters it has are in the satellites. It was specifically designed that way so that military personal could find their location without revealing their position by giving away tell-tale radio signals.
Now, once GPS has determined a position, that position can be sent to another party – a cellphone carrier, law enforcement, whoever – by the normal ways that any message can be sent over the radio waves nowadays. And this signal can be detected by the normal means as well. But this signal is not part of the GPS system.
“Sorry, after I removed it I threw it out”.
It is also worth noting that most modern radio receivers (gps works via radio) also transmit weakly. The received signal is frequency shifted by by one or more offset(s) produced by local oscillator(s). These oscillators leak to a greater or lesser degree, and can be detected by nearby instruments designed to listen for them. This is how “radar-detector-detectors” work.
You can’t appeal a SCOTUS decision; there is nowhere to appeal it to.