by Gary Wollenhaupt

Created on: February 10, 2009

Our society has suffered from the spread of cell phones and the cluelessness of their users. Who hasn't seethed through one side of a conversation about an incredibly personal situation?

Some people are tired of it and they're not going to take it anymore. Cell phones are basically handheld two-way radios. So like any radio, the signal can be disrupted, or jammed. Devices that do just that are available. But you may want to think long and hard about buying or using one.?

Disrupting a cell phone is the same as jamming any other type of radio communication. A cell phone works by communicating with its service network through a cell tower or base station. Cell towers divide a city in small areas, or cells. As a cell phone user drives down the street, the signal is handed from tower to tower.

A jamming device transmits on the same radio frequencies as the cell phone, disrupts the communication between the phone and cell phone base station in the cell phone tower. It's a called a denial-of-service attack. The jammer denies service of the radio spectrum to the cell phone users within range of the jamming device.

Cell phones are full duplex devices, which means they use two separate frequencies, one for talking and one for listening simultaneously. Other radios, such as walkie-talkies and CBs, are half-duplex. Only one person can talk at a time. Some jammers block only one of the frequencies used by cell phones, which has the effect of blocking both. The phone is tricked into thinking there is no service because it can receive only one of the frequencies.

Other jamming devices overpower the cell phone by transmitting a signal on the same frequency and at high enough power that the two signals collide and cancel each other out. Cell phones are designed to add power if they experience low-level interference, so the jammer must recognize and match the power increase from the phone.

Jammers will disrupt a signal regardless of the type of cell phone system in use. They are effective against AMPS, CDMA, TDMA, GSM, PCS, DCS, iDEN, and Nextel systems. Although these systems process signals differently, all cell phone networks use radio signals that can be interrupted. Old-fashioned analog phones and today's digital networks are equally susceptible to jamming.

To jam a cell phone, all you need is a device that broadcasts on the correct frequencies. GSM operates in the 900-MHz and 1800-MHz bands in Europe and Asia, and in the 1900-MHz (sometimes referred to as 1.9-GHz) band in the

• 1
• 2
• Next Page >>