All Flared Up

The sun, always known as the hot spot of the Milky Way, has been especially fired up this year.

The sun has reached the peak of an 11-year cycle of solar storms and flares. During the maximum, this year and last year, sunspots occur in the highest quantity and intensity. This most recent peak has brought with it some of the largest solar flares scientists have seen in years, a few comparable to the record 1989 flare that knocked out power in parts of Canada.

So what does the sun's mood have to do with the wireless industry?

A solar flare is a huge group of charged particles that get ejected with enough energy that they make it all the way to Earth, said Karl Audenaerde, Radio Frequency Systems (RFS; www.rfsworld.com) vice president of quality for the Americas. RFS designs and manufactures RF subassemblies for wireless infrastructure.

“What makes our life miserable in the telecommunications business is that (the particles) arrive with different energies,” Audenaerde said.

Those energies translate into radiation at different frequencies, including the frequencies for the microwave spectrum used for communication.

A particularly hellish flare shot toward Earth on April 2. The next day, AOL's (www.aol.com) instant messaging service was knocked down. Officials speculated that the intense solar flare caused the disruption. More major flares are predicted through the end of this year.

Bill Gill, U.S. Cellular director of network operations (www.uscc.com), said his company didn't worry too much about solar flares.

“Normally when they have big-time solar flares like that, it affects the lower frequencies more than it does anything else,” Gill said. “That's why it gets the pager companies around 450MHz. Normally, the solar flares don't give us that many problems since we're at 800MHz.”

Still, because major flares have been known to knock out power, Gill said that U.S. Cellular, like all carriers, has backup batteries and generators to maintain coverage.

Audenaerde said that when a powerful solar flare heads toward Earth, it includes so many charged particles that they can overpower wireless signals.

“The fact that we try, for safety reasons, to achieve RF communication at the lowest practical levels, makes us more sensitive,” he said. “Our level isn't so high, so nature's level doesn't have to be all that much stronger to overpower us.”

Bill Burrows, IFR Systems radio test (www.ifrsys.com) team leader, said IFR tests cellular radio signals under ideal conditions, adding that they have never tried to duplicate a solar flare and test its effects on signals.

Basically, the flare “would cause an increase in the background noise level, which may or may not prevent the radio from working,” Burrows said. “We do not generally test for that sort of natural occurrence.”

Audenaerde said industry officials were aware that solar flares could affect RF signals and disrupt communication, but many don't delve deeper to get a better understanding of the problem.

“The average (wireless) engineer knows that it is a problem, but they've never looked at the physics of it.”