INTERNET NEWS, OCTOBER 25, 2003 By Robert Roy Britt (SPACE.COM Senior Science Writer posted: 02:12 pm ET 06 March 2002) http://www.space.com/spacewatch/space_weather.html

Next time your cell phone drops a call, don't rush to blame your service provider. The culprit may well be an angry Sun.

A new study of 40 years of solar data shows that during peaks in activity, bursts of energy from the Sun can potentially cause dropped calls for some cell phone users across wide areas twice per week. The problem is caused when radio waves associated with the bursts hit cell phone towers, creating static that overwhelms the signal at the tower, where calls are relayed.

The result, for you, may often be sudden silence.

These flashes of radio energy arrive at the speed of light, roughly 8 minutes from the Sun to Earth.

"There's absolutely no warning," said Dale Gary, a physicist at New Jersey Institute of Technology and leader of the study.


In a telephone interview, Gary explained that the problem has to do mostly with the fact that cell phone towers need to face the horizon in order to communicate with users and other towers. Those that face east or west look directly into the Sun at sunrise or sunset. If a burst occurs then, the tower sustains a direct hit and is unable to sort out wireless calls from unwanted signals.

Which, for commuters, could mean isolation during drive-time. The events can last anywhere from a few minutes to a couple of hours.

"If you have poor service normally, you'll have worse service when there's an event like this going on," Gary said, adding that there is no way for you to know if your calls are cut off due to spotty service or an solar event.

Gary and his colleagues studied four decades of solar data provided by the National Oceanic and Atmospheric Administration. A paper on their work will be published March 7 in the journal Radio Science, published by the American Geophysical Union.

The Sun's activity runs in roughly 11-year cycles, and the study covered four peaks in this cycle. During peaks, the Sun has more sunspots and spits out more hot gas in the form of solar flares and coronal mass ejections, along with the increased radio emissions.

The researchers found that, on average, bursts powerful enough to disrupt wireless communications occur 10-20 times per year.

Or maybe more

In a follow-up study that has yet to be published, however, Gary and his colleagues looked deeper into the data and found hints of more events that were missed by an evolving monitoring system that dates back to 1960. Gary said the newer study shows that during peaks of solar activity, when bursts are much more likely, potentially disruptive radio spikes can strike every 3.5 days. During the years-long lulls in the solar cycle, as many as one disruption every 18.5 days might occur.

The most recent peak in the solar cycle -- a stretch of time that actually last for months -- occurred in July 200, but NASA scientists say a second peak surprisingly cropped up in recent months.

Gary said there's little chance of solving the problem soon. Future reception might be improved, though. Towers could be positioned to point anywhere but east and west, he said. And cell phones might be designed to handle higher levels of noise. But that means making them more powerful, raising possible health concerns.

The research team also included Louis Lanzerotti of Lucent Technologies' Bell Labs, along with Bala Balachandran and David Thomson, who were at Bell Labs when the research was done.

Reported by: Sol Jose Vanzi

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