Global Positioning Systems (GPS) are commonly found in cell phones, computer systems and stand-alone devices that can be used on vehicles. There are two types of GPS systems that are usually used --- a logger tracking system that stores your location on a computer system, and a real-time tracker that will be able to pinpoint your location at any given time. If you suspect that your car has an unauthorised GPS tracking device installed in it, then you can jam its signal buy installing a GPS blocker.
Install the GPS blocker on your car. Plug in the GPS blocker via your vehicle's cigarette lighter, simultaneously activating it. The plug and play feature of a GPS blocker lends for easy installation. Your vehicle will be invisible to any GPS tracking devices.
Unplug the GPS blocker whenever you don't need it. Remove it by disconnecting it from the cigarette lighter on your car.
Use a GPS jammer as an alternative to a blocker. If you do not want an obtrusive GPS blocker, or if you don't have a means to power it via a cigarette lighter, then invest in a hand-held GPS jammer. These will jam a GPS signal to receiving satellites, rendering you and your car invisible. Some models are as small as a cell phone, allowing you to carry them discreetly.
Many GPS blockers can run up few hundred dollars. The GPS blocker works by nullifying and cancelling out any signals emitted from any on-board tracking devices. More expensive GPS blockers tend to block signals for up to a few hundred feet, while more economical GPS blockers will have a smaller radius of protection.
Check with your local authorities to make sure the GPS blocker or jammer is legal in your area. Do not tinker with GPS devices installed by police officials. Many states have strict laws about GPS devices installed by officials. Check with your local law enforcement agency and inquire about laws relating to GPS devices.