NETWORK JAMMERS: A Disruptive Service

Alleged misuse of cellphones by  Pappu Yadav, MP, RJD in Beur Jail led

the Supreme Court to permit the installation of mobile phone jammers in all

jails across the country.

A division bench comprising of Justice N Santosh Hegde and Justice SB Sinha

has asked mobile service providers, Bharat Sanchar Nigam (BSNL) and Reliance

Infocomm to inform the court on how this facility could be installed in the

central jails, to begin with, for preventing "highly influential and

powerful personalities from misusing mobile phones while being lodged in

jail".

This misuse has to be stopped across the country in all jails and the process

could begin by installing jammers at the central jails, the bench

observed. 

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. Depending upon

the functionality, jammers can block radio frequency in one particular band (GSM

or CDMA) or sets of bands (GSM/CDMA/VHF/UHF).

Range of jammers varies with respect to different networks in a given location

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.

Jammers Vs Interceptors



For jails, service providers can opt for either of two solutions-detectors

or 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 $5,000 and $35,000.

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

$200,000.

Deploying Jammers/Interceptors



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.

Pravin Prashant