Friday, November 19, 2010

Network Jammers & Interceptors

What are Jammers?
So, what is the basic functionality of jammers? Jammers are high frequency transmitters deployed for blocking mobile signals from reaching BTS (for outgoing calls) or mobile phones (for incoming calls).

The jammers can act as a virtual transmitter and interfere with the normal working of cellphones, blocking both incoming and outgoing calls.

Jammers Vs Interceptors

Used mainly by military and law-enforcing agencies, deployment of jammers is considered illegal in most of the countries. The primary goal of jammers is to block cellphones in areas where they are forbidden by law, such as jails and in other places where it creates a nuisance, such as: churches, theatres, concerts halls, or conference halls.

For jails, service providers can opt for either of two solutions-detectors & jammers; and interceptors. In the first case, radio signals are detected by putting detectors in different cells, wherever required, and when the signals are detected it jams the signals.

This helps in jamming a particular area of the jail where prisoner movement takes place rather than jamming the entire jail and affecting the entire communications system. Its cost ranges between RS 200,000 and Rs 14,00,000.

Also, service providers can opt for interceptors that are currently in use by majority of the jails worldwide. Considered to be an intelligent device, the interceptors act as an all in one device and perform functionalities of a sensor, jammer, and recording system.

So, depending upon the conversation, one can either jam or record. The intelligent system costs are on a higher side and it is in the range of Rs 80,00,000.

But before deploying any of the two solutions, the service provider has to do a site survey to test the signal as is done in the case of installation of BTS. Since, jamming range is a function of signal strength received form a nearby base station and varies from one location to another. Even the jamming range varies with respect to different networks in a given location. Jamming also depends on topography of that area, thickness of the wall, reflection/absorption of signals in the given area, area to be covered, and frequencies to be jammed.

Once the survey is done, the service providers are in a better position to design an efficient system by knowing the number and positioning of the jammers. The service providers can either opt for a particular frequency band (GSM/CDMA) or can opt for a mix of VHF/UHF/CDMA/GSM/satellite phone/WI-Fi/Bluetooth/DECT. Care should also be taken to see that in case of power failure there are adequate backup facilities so that the jamming/interception systems can function even without assured power supply.

Once all these factors are taken into account, service providers can ensure that jamming/interception system is foolproof and will also help in preventing highly influential and powerful personalities from misusing mobile phones while being lodged in jail.