# How do I tell if a GPS tracker has been installed on my car? **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2009, 12:05pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018 "2009-05-11T12:05:46Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [May 11, 2009, 12:05pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/1 "2009-05-11T12:05:46Z")
Not that I’m paranoid or anything 😉 A Wisconsin court has recently ruled that the police do not need a warrant to install a GPS on a suspect’s car. [link1](http://www.chicagotribune.com/technology/chi-ap-wi-gps-police,0,5867383.story) [link2](http://www.wicourts.gov/ca/opinion/DisplayDocument.html?content=html&seqNo=36414) [Google](http://www.google.com/search?q=detect+gps&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a) suggests that they’re pretty hard to detect, and that you’re better off trying to jam one. I thought I’d check if any of you all had some super secret Doper knowledge on the topic. ---
**Author:** ![Bongmaster](https://avatars.discourse-cdn.com/v4/letter/b/6a8cbe/32.png) [@Bongmaster](https://boards.straightdope.com/u/Bongmaster)\ **Post date:** [May 11, 2009, 3:59pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/2 "2009-05-11T15:59:44Z")
There seems to be no shortage of “anti-spy” sites selling solutions but I guess it will depend on the method of tracking. If its passive, ie sending out no active signal, I’m not sure how you’d defeat that aside from a very thorough search of your vehicle. If its active and sends out a signal then a proper detector should revel its general location. Frankly I’m a little disturbed that the police can do this without a warrant. In my mind your vehicle is your own personal property and for the law to sneak in and plant a tracking device without a warrant seems like they are not allowing for proper oversight. ---
**Author:** ![redshift](https://avatars.discourse-cdn.com/v4/letter/r/bbce88/32.png) [@redshift](https://boards.straightdope.com/u/redshift)\ **Post date:** [May 11, 2009, 4:31pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/3 "2009-05-11T16:31:20Z")
Wrap your car in tin foil. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [May 11, 2009, 4:46pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/4 "2009-05-11T16:46:14Z")
> [@redshift](#): > > Wrap your car in tin foil. I used it all on my head ☹ 😃 Any idea what frequency the GPS signal is broadcast on? I’m sure one could design a faraday cage that’s see-though. ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [May 11, 2009, 5:01pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/5 "2009-05-11T17:01:29Z")
> [@Ruken](#): > > I used it all on my head ☹ > > 😃 > > Any idea what frequency the GPS signal is broadcast on? I’m sure one could design a faraday cage that’s see-though. Well, if you are a teenage daughter in the US and your father, the amateur radio operator, has installed a tracker in your car then it is probably transmitting on 144.390 mhz ( the US APRS freq). GPS trackers transmitting valid APRS packets on this freq are usually gated to the internet and available to any web browser. I would think though that the police would not use a transmitter. It would need an external power supply and would not always be in range. I would think that it simply records the gps positions every few minutes and then is recovered from the vehicle at some later date. ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [May 11, 2009, 5:08pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/6 "2009-05-11T17:08:33Z")
> [@Ruken](#): > > Not that I’m paranoid or anything 😉 > [Google](http://www.google.com/search?q=detect+gps&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a) suggests that they’re pretty hard to detect, and that you’re better off trying to jam one. I thought I’d check if any of you all had some super secret Doper knowledge on the topic. GPS antennas need a clear view of the sky. A GPS signal won’t pass though anything metal. Even tree cover is enough to block a signal. If the police were to place a tracker on your car, even the most cursory search would reveal it. Now, if they had enough time to install it so that it used your OnStar antenna, then you might have a tougher time. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [May 11, 2009, 6:17pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/7 "2009-05-11T18:17:20Z")
> [@UncleRojelio](#): > > GPS antennas need a clear view of the sky… If the police were to place a tracker on your car, even the most cursory search would reveal it. I have heard of devices that attach underneath a bumper by means of a quick magnetic mount. The antenna is normally out of sight, but emerges when the vehicle is in motion - thus making the device unlikely to be detected by a casual inspection. Sorry, but I wasn’t able to Google up any useful links for this. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [May 11, 2009, 6:22pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/8 "2009-05-11T18:22:14Z")
> [@UncleRojelio](#): > > I would think though that the police would not use a transmitter. It would need an external power supply and would not always be in range. I would think that it simply records the gps positions every few minutes and then is recovered from the vehicle at some later date. I think you are correct that many GPS-based tracking devices simply record position for later retrieval. But it would not be particularly difficult to include a cellphone-based transmitter and a battery sufficient for many days of (say, hourly) position-history reports. ---
**Author:** ![suranyi](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@suranyi](https://boards.straightdope.com/u/suranyi)\ **Post date:** [May 11, 2009, 6:24pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/9 "2009-05-11T18:24:13Z")
GPS itself is simply a receiver, not a transmitter. If it’s hooked up to a transmitter then it can transmit on any available frequency. Ed ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [May 11, 2009, 6:24pm UTC](https://boards.straightdope.com/t/how-do-i-tell-if-a-gps-tracker-has-been-installed-on-my-car/496018/10 "2009-05-11T18:24:25Z")
> [@Xema](#): > > The antenna is normally out of sight, but emerges when the vehicle is in motion … Now that would be cool. A little on the complicated-and-prone-to-failure side but cool nonetheless.