How Do Cell Phone Jammers Work

A cell phone signal jammer is used to stop nearby cell phones from sending or receiving signals, to and from the cell phone tower. This Techspirited article elaborates on how the device actually works.
Techspirited Staff
Ever been annoyed at a motormouth chattering on his cell phone, while you are forced to listen to his yakety-yak? Such people are loud and obnoxious, and talk while you're enjoying a meal at a restaurant or watching a movie at the theater. They talk in the bus or the train, while you're commuting, and even in churches, mosques, or other places of worship. They talk in the library or the museum, where people are expected to be quiet. They talk in the hospital, where sick people are trying to get better. Do you get irritated by such chatterboxes? Well, don't worry, because a cell phone jammer will come to your rescue.
A mobile phone signal jammer is usually used to stop cell phone use, in places where its use can disturb the surroundings. It stops all the wireless connections used by the mobile device, including Wi-Fi and Bluetooth.
The signal range of a personal jammer can be anything from 10 meters to 100 meters. It even works in congested areas, which may include walls and other obstructions. Portable jammers are pocket-sized, and look like cell phones themselves. This makes them easy to hide. Larger devices are more powerful, and have a larger range of operation.
The device has three antennas, one each for GSM, 3G, and DCS. It works by broadcasting a white noise signal or a wave bubble. To start off, you have to charge the device for at least an hour. Then, you have to turn it on. This will block all the wireless connections used by the cell phones present in the operational range. When you turn it off, phones can regain access to their wireless networks.
Jammers transmit a high-power signal of the same frequency as that of the cell phone, in a way that both the signals collide and cancel each other out. This is the basic working principle of any jamming device. Simpler devices block only one group of frequencies. Higher-end devices can block all the frequencies simultaneously. Cell phones are full-duplex devices, which means that they use two different frequencies; one for listening and the other for talking. Some basic jammers only block one of these frequencies. Yet, this has the same effect as that of blocking them both. This is so because the cell phone assumes that there is no service available, as it can only access one of the frequencies, which is not enough for its proper functioning.
Given below is a list of the main components of a jamming device.
  • Antenna: It is used for the transmission of radio signals.
  • Voltage-controlled oscillator: It produces the radio signal which overrides the phone signal.
  • Tuning circuit: Controls the frequency of the radio signal.
  • Noise generator: Produces random noise in a particular frequency range to jam the network.
  • RF amplifier: Boosts the frequency to a level high enough to jam the network.
  • Power supply: As the name suggests, it supplies power to the jamming device.
Legal Issues
A cell phone jammer also blocks emergency calls such as those that may be made to doctors and first responders. For example, it can stop the residents of a house from making a 911 emergency call. This is why its use is illegal, according to the telecommunications regulations in the United States. The FCC (Federal Communications Commission) thinks that it interferes with the public airwaves, and it infringes on a person's right to use a phone. It also interferes with medical devices, such as pacemakers used by heart patients. You are required to pay penalties, if you're found using the device.
Where to Buy?
You can buy a jammer on the Internet from foreign electronic companies. Some of them can be fitted with frequency filters, so as to only jam certain frequencies.
If used for the right purpose, cell phone jammers can definitely be a boon. Chatterboxes who keep talking on the phone, without taking into consideration the nature of their surroundings, can finally be kept quiet.