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Farm groups seek resolution of GPS interference issue

Issue Date: October 19, 2011
By Christine Souza

The resolution of a dispute regarding satellite communications leaves farmers and ranchers concerned about the operation of global positioning systems they use for precision agriculture applications such as planting seed, applying crop protection materials and harvesting.

The question involves the satellite spectrum, and whether a broadband company's proposed new wireless network will interfere with GPS systems. Virginia-based LightSquared received a conditional waiver from the Federal Communications Commission to use the satellite spectrum for a national wireless network, but preliminary tests indicated its network would interfere with satellite transmission to GPS devices.

GPS technologies are responsible for an estimated $19 billion in additional farm revenue each year, according to the American Farm Bureau Federation.

"California Farm Bureau Federation and American Farm Bureau Federation are working to ensure there is no interference with GPS receivers prior to granting LightSquared permission to operate its high-powered base stations," said Rayne Pegg, assistant manager of the CFBF National Affairs and Research Division. "Farm Bureau believes that high-speed broadband services, like the potential service offered by LightSquared, have great potential to bring economic development, better education and improved health services in rural America, but not at the expense of losing GPS."

AFBF Director of Congressional Relations R.J. Karney said to solve the interference problem, LightSquared has announced several different solutions, including operating within the lower 10-megahertz portion of its spectrum and operating at a lower power than permitted under its existing FCC authorization.

"LightSquared says there will be no interference with about 99.5 percent of GPS users just by doing this alone. Unfortunately for our members, we're that remaining 0.5 percent," Karney said. "Now, LightSquared is saying that it can come up with a technical fix to avoid interference with high-precision GPS by creating a filter. You can put the filters on the GPS units and that will stop the interference."

The House Small Business Committee held a hearing last week on the potential impact of LightSquared on small business users of GPS. The hearing focused on the impact on GPS use by farmers, as well as construction contractors, surveyors and general aviation. AFBF told Congress that the FCC and an independent technical company "must complete comprehensive and rigorous testing on all proposed technical fixes to ensure there is no interference between broadband and GPS signals."

Farmers who adopt precision-agriculture methods rely on GPS for accurate mapping of field boundaries, roads and irrigation systems; for precision planting; and for targeting the application of fertilizer and of chemicals that combat weeds and crop diseases. GPS also allows farmers to work in their fields despite low-visibility conditions.

Rice grower Josh Sheppard of Biggs, whose operation consists of 3,200 acres, said his family farm uses GPS technology in every aspect of its operation.

"GPS technology was adopted early in California and it has given us an advantage over other areas for our high yields," Sheppard said, "so if we don't have GPS to rely on, we're going to have a situation."

The issue has been recognized as "a serious threat to the reliability and viability of the global positioning system" by the Coalition to Save Our GPS, which includes a number of national agricultural groups. Farmer Don Cameron of Helm, who serves on the board of directors of coalition member the National Cotton Council of America, said he's concerned about the effect the satellite-spectrum issue could have on California agriculture.

"We use GPS-equipped tractors for many aspects of our farming, from precision row spacing to installation of multiyear drip irrigation systems in our field crops. Any disruption of this technology would create chaos with our current precision farming practices," Cameron said.

"It is also important that the cost of resolving this issue not be passed along to farmers and ranchers through higher GPS or equipment costs," Pegg said.

At the hearing last week, LightSquared provided a prototype of a filter that could be used to eliminate interference.

While testing completed earlier this year by the FCC confirmed that there is an interference issue with the proposed LightSquared wireless system and GPS, it is up to the FCC to decide how the issue will be resolved.

"One filter is not going to be able to replace all of them because each one is made differently, so our message to the FCC is that this needs to be fully vetted. We need to see that there is zero interference," Karney said.

(Christine Souza is an assistant editor of Ag Alert. She may be contacted at

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.

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