The cell phone jammer’s role is to interrupt the communication link (or network) between two (or more) “partners”, when they are trying to talk with each other or deliver certain data between them. Jamming the communication link between a Drone and its Operator is a specific case out of many more; we can try to jam the communication between a cellular and the base station, between two tactical radios, between a bomb and a remote control that is used to activate it, etc.
Sometimes the jamming signal arriving at the receiver input, can be lower than the communication (“partner’s”) signal and still prevail. This is happening because usually the receiver needs a certain “margin” between the two signals at its input, in order to be able to interpret one of them (usually the stronger one). However, in advanced communication systems, this “margin” can sometimes be even negative (meaning that the communication signal can be much lower than the jamming signal), and the receiver will still be able to interpret the “partner’s” signal, making jamming a much harder task.
Reasons to buy these equipment
That would mean every smuggled phone in the facility would be quickly identified. In addition, it would be relatively easy to create a list of permitted phones (owned by guards, office staff etc) and pass calls from those devices through to the communications networks. Alternately, we would have to ask exactly why it was that a guard needed a phone while on duty.
Mobile phones were seized from Block 1,2,3,4 and High-Security block 1. A jammer had been installed in the prison premises two months back. Last year, there were allegedly 72 mobile phone cases registered, while the number is already at 64 this year.
The state government had earlier allotted Rs 5 crore for procuring 12 mobile phone signal jammer to be installed in various central prisons to control the use of mobile phones by the prisoners. Two mobile phone jammers had already been installed at the Puzhal Central Prison.