Cell phone signal jammer in prison
In the battle to keep criminals from using contraband cellphones in prison, law enforcement may be a bit closer to having technology that could jam phone signals inside correctional facilities without affecting nearby communications.
In January, Perfectjammer said its researchers installed the jamming technology in a utility closet adjacent to a 13-by-eight foot cell on the ground floor of the prison's housing unit, according to the study. It successfully blocked cellphone transmissions in commercial bands between 700 and 2170 MHz, but did not disrupt commercial transmissions when monitored at 20 feet and 100 feet outside the cell, said the study.
The data in the report will be used by the Federal Bureau of Prisons (BOP) and the Department to understand the efficacy of micro-jamming, conduct further evaluation of wifi jammer technology, and develop recommendations for strategic planning.
Jammer testing and results
The test’s data show that the micro-jammer’s signal disrupted commercial wireless signals inside the prison cell, meaning that if cellphones were operating inside the cell, they would have been rendered inoperable.
The microjammer targeted CMRS service indoors in a single medium-security prison cell. Spectrum measurements of the jammer emissions were performed at two places inside the targeted prison cell and at two nontargeted nearby locations outdoors. GPS jammer emission measurements were performed at each location with multiple measurement bandwidths and detectors across a frequency range of 300 MHz to 4.34 GHz.
At the measurement locations inside the prison cell, measured differences in incident power between when the jammer was on versus off showed that jammer incident power levels were much greater than that of the ambient CMRS power levels. For the outdoor locations where jamming was not intended, the jammer’s incident power was measurable at 100 feet from the building. However, outdoors the incident jammer power levels were lower than the ambient CMRS levels. This was because the jammer signal strength was lower outdoors than indoors, while the ambient CMRS signals were stronger outdoors than indoors.
The fact that Burail jail has a cell phone jammer with 2G reception only made it easy for inmate Rajan Bhatti to use mobile phones having 4G network, as its signals cannot be jammed by the Burail jail jammer. An official of the Burail jail admitted that the 2G network jammer at the jail was of no use. “The jammer does not hamper the usage of 4G mobile phones which are in every hand nowdays and 4G SIMs are easily available,” said the official.
