February 09, 2013

A curious problem with WiFi

From Network World:

A giant radio telescope, a small school and a Wi-Fi problem
Students at a tiny Appalachian public school can't use Wi-Fi because any such network can throw the radio equivalent of a monkey wrench into a gigantic super-sensitive radio telescope just up the road.

Green Bank Elementary/Middle School is located just over half a mile away from the National Radio Astronomy Observatory's Green Bank Telescope in West Virginia. The NRAO says the 17 million-pound telescope is the most advanced of its kind in the world, boasting 2 acres of surface area which it uses to collect radio signals from around the cosmos. The facility studies everything from pulsars to the formation of stars to the movement of gigantic gas clouds in distant galaxies.

However, the GBT's extraordinary sensitivity means that it's very susceptible to human-generated radio interference, according to site interference protection engineer Carla Beaudet.

“If there was no dirt between us and the transmitter, a typical access point … would have to be on the order of 1,000,000 km [more than 620,000 miles, or about two and a half times the distance from the Earth to the Moon] distant to not interfere. Fortunately, we have mountains around us which provide lots of attenuation, so we're not seeing everything from everywhere,” she said in an email to Network World.

A standard Wi-Fi access point would wipe out a significant range of usable frequencies for the observatory.

A bit more:

The school, with its enrollment of 261, is in a tough position. Though quiet zone rules ban it from using Wi-Fi due to its proximity to the GBT, the rest of the schools in Pocahontas County are planning a move to digital textbooks in the next academic year. Moreover, the state of West Virginia will move to an online-only standardized aptitude test the year after that, which will also require Internet access for each student.

Pocahontas County Schools technology coordinator Ruth Bland worries that the district simply doesn't have the resources to cope.

“Short of wiring every classroom to have at least 25 drops and a laptop for every student, we will have a very difficult time providing digital textbooks or access to take the testing. The drops will require quite a number of switches and miles of cabling. All very costly,” she says.

I visited the old telescope several times with my Dad while growing up in Pittsburgh, PA — that one collapsed in on November 1988. It's replacement saw first light on August, 2000 and has done some really important work. Sadly, there is a move to de-fund its operation over the next five years — here is the website to save it:
The mission of this website is to prevent the closure of the National Radio Astronomy (NRAO) site in Green Bank, West Virginia and preserve the operation and use for national science of the Green Bank Telescope (GBT). To do so, this website will provide information and links to information telling you about the NRAO/GBT facility, its mission, history and accomplishment and what you can do to help.

Closing a facility like this would put the United States years behind any other facility for deep-sky observation. This scope is state of the art and to decommission it would be a death sentence as deferring maintenance would result in its becoming inoperable.

Posted by DaveH at February 9, 2013 03:29 PM
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