Radio-based systems operated by John Deere and Trimble/Case IH dealers continue to grow as well.

John Deere has seen its dealer-operated network expand to more than 300 million acres nationwide, up from 220 million acres in 2009. That assumes coverage in a 12-mile range from each base station.

Recent expansion has been driven in part by Deere’s introduction of its StarFire 450 RTK radios in January 2010, says Ryan Roloff, John Deere RTK network specialist. The StarFire 450 RTK radios, which must be licensed by the FCC, typically broadcast with 70W of power, compared to 4W for the unregulated 900-megahertz (MHz) spectrum used in most Deere networks.

“The 450-MHz radios still have a 12-mile range but can blast through trees and over gently rolling hills,” Roloff says. This capability has allowed dealers to expand networks in parts of the Midwest with more challenging terrain.

Networks operated by Trimble dealers in the U.S. now cover 550 million acres. That’s based at a 12-mile range from base stations, up from 425 million acres a year ago. Coverage is about 250 million acres at an eight-mile range offering sub-inch repeatable accuracy. Radio base station sales have slowed only slightly, even as other RTK options proliferate, notes Chad Pfitzer, RTK/VRS systems specialist at Trimble.