Spectrum management, never an easy task, has become much more complicated for the U.S. Army over the past three years. A tidal wave of wireless-triggered improvised explosive devices (IEDs) by Iraqi insurgents prompted the military to deploy an array of spectrum-jamming solutions to protect troops in harm's way. Jammers, however, do not discriminate between friend and foe and have been attributed to interfering with everything from tactical radio communications to unmanned aerial vehicle operations.

“A jammer's whole purpose in life is to reap havoc. So we're reaping havoc,” said Stu Timerman, director of the Army's Spectrum Management Office. “Three years ago, we had a situation where soldiers were getting killed left and right, so we needed to get something in the field. Since that time, we've had a chance to develop a better design in jammers [and better operational procedures.] … So yes, the [RF] situation now is better.”

Back in the days of the Cold War, spectrum management was relatively straightforward, according to Dakota Wood, a senior fellow at the Center for Strategic and Budgetary Assessments, a defense think tank in Washington D.C.

“Frequency management [was] usually thought of in terms of your own force,” Wood said. “It was an understood environment. You know your systems, what radios, what nets you were using — you're managing your own spectrum. The normal enemy you're planning against in the Cold War — the Soviets, the Chinese — you have a good idea as to the type of equipment they're using. You're going to try to jam their signal. Or you're going to try to exploit their communications.”

But even under the relatively uncomplicated electronic communications environment of Vietnam, the task of frequency management was challenging.

“We were never given the amount of frequencies you needed,” said Marine Corps Col. (Ret.) Richard Hartman. Serving as a division and Air Wing communications electronics officer, Hartman was in charge of allocating 300 frequencies across a 5000-person brigade.

Developing an operational plan required taking into account the available frequencies and equipment, the equipment capabilities, and the topology of the area's terrain. Mountains provided a way to reuse line-of-sight between operating units, but the plan was “dynamic” and would change as troops were moved around on the battlefield.

“Helicopter pilots had 43 different frequencies to change,” Hartman said. “They had to change frequencies to fly safely through artillery fire zones.” Failure to monitor an artillery radio net could result in flying through a barrage of shells.

Iraq presented a much different electronic landscape than Vietnam. “They don't have the same [FCC-driven] spectrum management as we do here in the states,” Wood said. “It's relatively unregulated in terms of power and the bands they can transmit on.”

For instance, the typical U.S. cordless phone has, at best, a range of a couple hundred yards; in comparison, an Iraqi cordless phone with stronger transmit power may be good for nearly a mile. “When you get into Iraq,” Wood said, “[you] find that everyone is using just about anything to send a signal.”

Insurgents building IEDs first started out using a wide selection of consumer electronics devices as wireless triggers, ranging from garage door openers to cordless phones. U.S. and coalition forces deployed multifrequency jammers to cover the frequencies used for the IED triggers, but the devices quickly ended up interfering with a broad range of gear, including convoy communications nets and even the links to unmanned aerial vehicles.

Meanwhile, the insurgents weren't standing still. “What people need to appreciate is that combat is a competitive nature, and a constantly iterative process,” Wood said. “There's a constant back-and-forth competition. If it doesn't work, you take a step back and get a different way of dealing with the situation, and that's something new I have to deal with.”

Bomb makers started using trigger devices with more power, employing a wider range of frequencies, and incorporating cell phones into their designs. To counter, U.S. forces started using programmable jammers and dispatched electronics warfare experts from the Navy to fine-tune the devices.

Prior to its experiences in Iraq, the Army had a 10-week training course for spectrum managers. Today, the Army has made the spectrum manager an MOS — military occupational specialty.

“We needed to professionalize it, get people who are trained and qualified in spectrum management with all the different and complex issues we're dealing with,” Timerman said. “The introduction of jammers made us reassess the complexity of the environment.”

An 11-week course developed for the new specialists includes electronic warfare practices and the introduction of jammers into the regular inventory. By creating the MOS, the Army is ensuring that spectrum managers are clearly identified in the ranks and assigned to where they are needed. With the increasing complexity of the electronic environment and the Army's reliance on advanced technologies, consideration also is being given to assigning two spectrum managers to its brigade combat teams; currently, each brigade only has one designated slot.

Timerman expects technology to play a role in helping the new specialists in their roles. The coalition joint spectrum management and planning tool (CJSMPT) has been in development for a year and will provide a real-time, three-dimensional visual tool for viewing frequency use on the battlefield. The hope is that the tool ultimately will automate spectrum planning and make spectrum management more efficient, as its simulation capability can predict and visualize potential interference from on-the-move forces. The CJSMPT is expected to lead to GEMSIS — the Global Electromagnetic Spectrum Information System — a suite of tools plugged into U.S. military networks to provide spectrum management on a near real-time basis.

Other solutions will come from improvements in jammers, radio design and software, said Joe Tavormina, group director of the spectrum program office of Foster-Miller, an engineering firm in Waltham, Mass.

“[Military] radios are concentrated in frequency areas, but 50 MHz away, there's a big area not being used,” Tavormina said. “We want to get better assignments of frequencies. … I think solutions are going to be wrapped up into software-defined radios.”

Foster-Miller, a division of QinetiQ, has incorporated software algorithms into its SIREN IED jammer to provide more intelligence in analyzing signal threats. Instead of jamming everything, SIREN sifts through all types of emissions and selectively jams realistic threats. “We can offer some advances in the size, weight and power of jammers,” Tavormina said.

Regardless of solutions, the future only will provide more challenges. For instance, the Army's move to network-centric warfare treats nearly every soldier and piece of equipment on the battlefield as an Internet node requiring broadband connectivity — and more spectrum. Meanwhile, broadband wireless technologies such as WiMAX, high-speed packet access (HSPA), and long-term evolution (LTE) are flooding the air around the globe.

“With our information culture we have, we just need more and more sophisticated information,” Timerman said. “That really comes to wider use of the spectrum with a lot of things we're looking for in the future, both in the government and civilian sectors. We have to find better ways of utilizing spectrum.”