The jamming device overloads the mobile phone by sending signals at the same frequency and high enough power, so that the two signals collide and cancel each other out. Mobile phones are designed to increase the power when they encounter low level interference, so the jammer should recognize and match the increase in power of the phone.
Cell phones are full duplex devices, which means they use two different frequencies, one for talking and one for listening simultaneously. Some jammers block only one of the frequencies used by the phone and therefore block both frequencies at the same time. The phone was tricked into thinking that there was no service because it could only receive one of the frequencies.
Less complex devices block only one set of frequencies, while complex cell phone jammer can block multiple types of networks at once to prevent dual-mode or triple-mode phones from automatically switching between different types of networks to find a signal. open. Some high-end devices block all frequencies at once, while other high-end devices can be tuned to specific frequencies.
To jam the phone, all you need is a device that broadcasts on the correct frequency. Although different cellular systems treat signals differently, all mobile phone networks use radio signals that can be interrupted. GSM used in digital and PCS-based cellular systems operates in the 900 MHz and 1800 MHz frequency bands in Europe and Asia and in the 1900 MHz (sometimes referred to as 1.9 GHz) frequency band in the United States. United. The jammer can broadcast on any frequency and is effective for AMPS, CDMA, TDMA, GSM, PCS, DCS, iDEN and Nextel systems. Old-fashioned analog phones are just as susceptible to interference as today's digital devices.
The actual range of the jammer depends on its power and its local environment, which may include hills or walls of buildings blocking the jamming signal. Low-power jammers can block calls within a radius of about 9 m (30 feet). Higher wattage units will create a unitless area as large as a football field. A device used by law enforcement can interrupt services 1.6 km from the equipment.