Global Positioning System (GPS) Jammers

I recently bought a Bluetooth GPS receiver and software for my PDA and it has changed the way I drive. I find myself traveling to a lot of new places and I often end up renting a car when I get there. With my GPS system I can pre-load maps and location destinations (like hotels and meeting addresses) before I arrive. When I get to the rental car I turn the receiver on, put it on the dashboard and turn the PDA on. In a couple of clicks my PDA is talking to me, guiding me turn my turn to where I'm supposed to be going. The device has saved me a lot of time, stress and confusion when I'm trying to get to someplace I'm not familiar with.

GPS locations are based on positioning relative to 24 satellites orbitting 12,000 miles above the earth and generating (by the time they get to earth) relatively weak wireless signals. As a result, it does not take much signal power to jam them. GPS works on two different frequencies:1575.42 MHz for non-military public use and 1227.6 MHz used for the United States military. The military has used GPS jammers for a long time to confuse the enemy. Consider a GPS guided missile directed at a specific location - if a target location is jammed missiles will likely not be able to hit that location.

GPS jamming went mainstream with an article published in Phrack Magazine in January 2003 titled Low Cost and Portable GPS Jammer. Here's a quote from the article: "the onslaught of cheap GPS-based navigation (or hidden tracking devices) has made it necessary for the average citizen to take up the fine art of electronic warfare."

Here's a few more quotes from the Phrack article:

Several companies now sell "hidden" GPS based tracking devices which mount inside
or underneath your vehicle.  Some transmit the coordinates, via cellular phone, of
your vehicle's present and/or past locations for weeks at a time without battery
changes or court orders!

Vehicle rental companies have been known to use GPS tracking devices to verify you
don't speed or abuse their rental vehicles.  The unsuspecting renter is often faced
with these hidden abuse "fees" after returning the rental vehicle.

Law enforcement agencies...... keep track of house arrest prisoners with simple GPS
based tracking bracelets.  Some even use GPS for automatic vehicle location

Cellular phone companies, trucking companies, private investigators, toll-roads,
aircraft, those "protect your child" systems and many more services are all fully
involved with the use of GPS based tracking.  The problem is, do you really want
everyone to know where you are?

I was watching local news the other evening....... a small town near where I live has installed GPS units on all of the town highway department trucks. The location of all vehicles is monitored and administrators know where their vehicles are, where workers have been and where they are going. The town justified the purchase based on the price of gas and wear and tear on the vehicles and expected a full return on the technology investment within 3 years.

Some that work for these kinds of companies and organizations don't like the idea of someone knowing exactly where they are all the time and have obtained, or are considering obtaining, GPS signal jammers. A quick search on eBay for "gps jammer" yields several battery and cigarette lighter devices starting at $76.

MicroVideoX.com has a video posted on YouTube demonstrating their GPS Counter Track device:



Interesting technology and the devices look like they are fun to play with. However, I don't believe I would risk my job.