Cell Phone Bombs

Either way, lithium ion cobalt batteries' easy availability and chemical instability make them attractive to terrorists who want to use them for "battery bombs." (Melamed notes that because laptops use the same battery material, terrorists may choose to use the larger laptop battery as the main explosive, and the smaller cell phone battery in place of a blasting cap.)

Valence is focusing on large format batteries, replacing lead acid and nickel metal hydride with its Saphion I technology. The company is not currently focusing on consumer electronic devices for its Saphion I chemistry. Akridge says: "Lithium ion batteries that use cobalt-based cathodes are still the best choice for portable electronic devices because of their light weight and storage capacity for their small size. Phosphate-based cathodes have better safety characteristics than those containing cobalt. Temperatures that cause phosphate cells to catch on fire cannot be generated by the phosphate chemistry. Phosphate cells, having lower energy density than cobalt cathodes, make them less attractive for consumer devices."

How jamming equipment stops IEDs

Although Melamed could not discuss specifics, a jamming device blocks the cellular downlink frequencies, preventing a cell phone's ability to receive an incoming call. (Uplink capabilities still function.)

Jamming equipment only stops some of a cell phone's functions from working. It cannot prevent a cell phone's alarm function — effectively, a timing device — from detonating a bomb. Melamed estimates it can impede half of all cell phone bombs, along with remotely controlled bombs that use other tools, such as garage door openers or toys. Separate equipment exists to prevent bombs that use the alarm function. "Terrorists use the simplest materials they can find to make bombs," Melamed notes. In other cases, it's possible to control cell towers' signal; some phones turn themselves off if they can't find a signal. In others, a bomb technician may "mate" with the phone to set the timer back.

Melamed says jamming equipment is very location-specific, meaning cell phone traffic in an entire urban area could not be jammed. "We compare it to a police officer stopping vehicular traffic: only that particular street is stopped, and only in one direction," he explains. "Our equipment can jam as much as necessary, but only for a specific period of time and only in a certain building or subway station. Officers can also select the frequencies they jam. For instance, they could jam downlinks for everyone's phone except emergency services.' " During a period of heightened alert, police might choose constant jamming for areas like close-to-the-surface subway stations. The goal, Melamed says, is to avoid the pandemonium terrorists want to elicit.

Does law enforcement need jamming equipment?

"FEMA [and its response to Hurricane Katrina] showed us that federal agents are not the first line of response to catastrophic incidents," says Melamed. While cell carriers can shut down towers in an emergency — in much the same way the airline industry grounded all flights on 9/11 — an emergency protocol to do so only recently became available, and falls under federal purview.

Melamed says these issues are complicated by the possibility that cell carriers may extend signals into commercial airspace. "Phone signals don't interfere with navigation; no plane ever came down because someone forgot to turn their cell phone off," he says. That the need for constant communication outweighs public safety is already an issue in Washington, D.C., where carriers provide underground signals for subway commuters.

A bomb squad could use a jamming device to prevent a primary explosive from detonating; or, following a primary attack, prevent additional bombs from going off. However, Melamed says agencies that have contacted his company have many more uses in mind. Hostage negotiators could jam all signals except the single line they need; narcotics officers could jam signals on a street where a bust was about to take place, severing spotters' ties to dealers. Patrol officers could jam signals on vehicles they pursue or stop, guaranteeing that they could get — and keep — subjects' attention. And correctional facilities could jam downlinks to jails and prisons, preventing inmates from "doing business" with their gangs or other associates on the outside.